In this article I’ll cover the general things that apply to all Fiero versions, then later I’ll break out the version specific and detail items.
Contrary to popular belief, vacuum plumbing problems are a major issue. Even small vacuum leaks can cause major headaches.

A major problem? Why?

The ECM will try to compensate for leaks up to a certain size. The leak will often cause performance problems without setting DTCs in the ECM. Depending on exactly where the leak is, it can unbalance the entire engine.
Let’s say you’ve got an Iron Duke and the EGR is leaking slightly around the base. This allows air to enter the intake right near the middle cylinders, leaning them out just a little. The ECM tries to make up for this by increasing the fuel feed. The end result is that the end cylinders are probably running rich. The car may seem to run pretty normally but you’ll take a hit in fuel economy and most likely you’ll have strange drivability problems that are often hard to duplicate.
Any vacuum leak is letting air in after the IAC and Throttle Plate. The ECM tries to make up for this by closing the IAC and likely increasing the fuel flow. This can cause a number of odd things to happen, like goofy Idle and hesitation. Ultimately, there is no such thing as an acceptable vacuum leak. All leaks must be found and fixed.

Tools:

Spray can of “throttle body” and Fuel Injection cleaner. (This is safe for all EFI. Carburetor cleaners can sometimes do damage to EFI parts. Don’t use it.) ((I do NOT recommend most people use the propane search method. It is far to easy to start a fire with this method, especially if done with improvised equipment.))
Assorted line plugs and port caps.
Hand operated vacuum pump such as “Mighty Vac” or equivalent. If you are buying one of these, just get the whole vacuum brake bleeding kit. Then you’ll get more use from it and bleed the brakes or clutch allot faster.

General:

Eliminate the nonessential items first. Start the car after each of the following and see if it has solved your problem.
Disconnect the 2 lines to the Fuel Vapor Recovery canister. Plug the ports on the throttle body and/or manifold.
Disconnect the Cruise Control line and plug its manifold port.
Disconnect the EGR line from the throttle body and cap its port. (I’ll get more into the EGR later)
In the front compartment disconnect and plug the line on the brake booster. DO NOT attempt to drive the car with the booster disabled! The brake booster can leak internally. Carefully inspect the booster vacuum line and all it’s clamps. All joints in this line should be clamped and the rubber hose sections free of cracks or other damage. Make sure there are no rusted sections of steel line. (The section inside the cabin is likely OK.) If any section of the line looks questionable spray the suspect area with EFI cleaner. Check the line to the MAP sensor carefully. Hard line doesn’t like being bent, especially when cold. (DO NOT spray the MAP sensor with solvent when searching for a vacuum leak!)
If the above have not solved the problem then carefully begin searching with the spray cleaner. Start the car and spray the throttle body mountings and work your way around whatever isn’t disconnected. DO NOT spray the distributor, coil(s), sensors or IAC with cleaners or solvents! You will likely damage them or start a fire. Use as little spray as possible to find the leak.
Don’t soak things. Test an area, let it dry then test another. The RPMs should change one way or the other when you spray the leak.

Fuel Vapor Recovery Canister:

This device catches vapor from the fuel tank. It uses 2 vacuum lines. The large (purge) line is connected to manifold vacuum. This line is used to ventilate the canister. The smaller (control) line is connected to the main bore of the throttle body and only opens the purge valve beyond a certain amount of throttle.
Problems with the canister can include failure of the purge valve to close and cracks in the purge valve body or canister itself.
There is also a fiber filter in the bottom of the canister that should be replaced periodically.
Another problem that this device can develop is flooding. Flooding is caused when liquid fuel is forced up the vent line into the canister. A flooded canister can cause rich mix problems with the engine. A canister that has been flooded should be replaced. To prevent flooding avoid “topping off” the fuel tank when you fill up. If the nozzle of a retail fuel pump is defective, and they often are, then you can pressurize the fuel tank and force fuel up the vent line into the vapor canister. It doesn’t take allot of liquid fuel to screw up the canister. Even if the pump doesn’t force fuel into the canister, fuel expansion in the tank can and often will. Either way, topping off the tank is a bad idea.

Quick test….

Disconnect both lines and connect a hand vacuum pump to the large line. Give the pump a squeeze and make sure the line holds vacuum. 10 inches is plenty of vacuum for this test.
Now use the pump on the small line. Draw only 3-4 inches maximum on this line! More than a few inches vacuum can damage it. While you have vacuum on the control line, blow into the purge line. Air should move freely. While blowing into the purge line release the vacuum on the control line. The valve should close and block all airflow in the purge line.

Cruise Control:

Leaks in the cruise control servo diaphragm cannot be fixed. Some people have had luck cleaning the valves on the servo and/or the dump valve. (The dump valve is a backup valve that kills the cruise when the brake is pressed and is mounted separately from cruise servo.)
There is also a vacuum reserve canister in the cruise system. Older style canisters are often metal and are prone to rusting out. Replace these with new style plastic canisters.
There are 2 styles of canister. The ones with 2 fittings usually have integral check valves. The ones with single ports are used with a check valve in the manifold line.
You can replace the can and inline check valve with a 2 port vacuum ball, but you must also insure that the plumbing is redone to work correctly. I think the larger port on these is usually the manifold side but test it to make sure. The exact size of the canister is not very critical. Any canister of approximately the same volume or greater will work. You can get good used plastic canisters for about nothing at any salvage yard. The plastic ones will last nearly forever. Just make sure the check valve is working before you leave the yard. (Blowing into one port is very easy. The other is not going to let you if the valve works.)
BTW: You can get these from many American made cars. It doesn’t have to be a GM product.

As you can see, changing to the vacuum ball also simplifies the vacuum lines quite a bit. If you make this change, and cruise stops working, then you may have put the lines on the Vac Ball wrong.

Brake booster:

The brake booster unit should not be disassembled. If you believe it leaks then it will need to be replaced. You generally can’t get parts for the booster and there is a very heavy spring inside it that likes to send thing flying.
The check valve that the vacuum line connects to can go bad. This usually manifests as brakes that work right only at idle. The check valve shell can crack and cause a vacuum leak. You can replace the valve by itself. Try MotorMite’s HELP! or VacuTite lines.
Don’t forget to check the brake filter on cars that have them. The plastic shell of them is pretty tough but it can crack or melt. The brake filter does need to be replaced on occasion. If it plugs up you will have brake problems.

Hard lines:

Hard vacuum line can be a pain to service. You can get the line but finding the correct fittings can be difficult at best. (The rubber fittings are reusable if they are in good condition and sealing tightly to both the line and the port.) If you replace hard line with soft line make sure the new lines are not pinched or collapsed from bending too tightly. The soft line should be sized to properly slide onto the fittings and stay tight. Don’t stretch undersized line to fit. It will likely split in short order.
New Hard Line can be shaped or straightened by careful use of heat. (Try dipping the line in very hot water.) Be careful not to pinch or stretch the softened line. Don’t try to form old lines. They usually break even when warmed.
Note: If you replace the MAP sensor line with soft line then keep the line as short as possible. The soft line will have a larger internal volume per inch of line than the hard line. This increased volume can affect the reaction time of the MAP sensor. A slow MAP sensor will likely hurt performance. Even when using hard line it is best to keep the MAP feed short as possible.
Make sure the steel PCV valve line is not rusted through anyplace and that both elbows are sealed. GM recommends clamps on the elbows. Be careful with the clamps that you don’t cut into the soft elbows.

4 Cylinder specific:

The 4 cylinder EGR is bolted directly to the intake manifold. Make sure it’s tight. The bolts have a nasty habit of coming loose. Replace the gasket if the bolts have come loose at all. (The FelPro EGR gasket costs about $1.00 at most parts stores.)
The EGR valve is hard to test for leakage. Make sure the valve isn’t binding.
One way to test EGR problems is to make a block off plate and seal the manifold openings. Then run without it for a little bit. Note: Permanently running the car without the EGR is a crime in the United States. Running the car without the EGR can cause detonation, which can damage the engine. This is a testing procedure only.

87-88 TBI:

Be careful not to spray the MAT sensor’s plastic parts with solvent. Depending on the solvent used, you can damage the sensor. The MAT sensor is located to the right of the TBI unit and is screwed into the intake manifold. Avoid intake backfires in these engines. If the car backfires into the intake, the MAT sensor should be inspected for damage. If the MAT sensor has been cooked it should be replaced. (The MAT sensor is used in calculating fuel/air ratio.) Don’t over tighten the MAT sensor or you may split the intake manifold.
Check the base of the TBI for leaking, especially if there is any evidence the air cleaner has hit the trunk wall. (Read the torque strut article.) There is a specific sequence to tighten the 700 TBI to the manifold. Read the TBI 700 article. The emissions vacuum line map for these years is in the TBI 700 article. That map doesn’t include cruise.

V6 specific:

You’ll need to check the EGR plumbing very carefully. Use extreme caution if you decide to use spray or gas searching on this. The V6 EGR plumbing gets hot enough to light off many solvents on contact.
The V6 EGR control valve must also work properly. If it’s acting up, try electronics parts cleaner. Don’t use the cleaners with lubricant in them. The lubricants will hold dirt and quickly clog the valve up again. (Most “Tuner wash” and contact cleaners have lubricants in them.)
To test this valve, with the engine off, blow into the line connected to the EGR valve. The air should exit the vent hole. Cap the vent hole and blow again into the EGR port. No air should come out the manifold port.
To test during run, connect a vacuum gauge to a T in the EGR valve line. You should be able to see the vacuum rise and fall when the ECM has activated the EGR valve. Using an ECM scanner with the vacuum gauge may be helpful. I think the ECM will tell you when it’s trying to open/shut the EGR. You should see a corresponding change on the gauge. (I think the ECM may also report the EGR vacuum sensor status. I can never remember just what ECM reports what.) You must also carefully inspect the entire plenum. If bolts have come loose you may be able to simply tighten them but likely you will need to replace the gaskets.
Rodney Dickman now offers formed metal vacuum lines for the V6.

Warning! Don’t force anything into the ALDL connector! If you damage the connector then you can have problems when using ECM scanners and other tools that have the proper size terminals.

Note! It is possible that the ALDL may be installed with the Key up or down.
The above picture is Key Down. Use the key sticking off the ALDL by terminals C & D to determine which way the ALDL is positioned.
With the key down, when you are sitting in the drivers seat, Terminal A is on the bottom row on the passenger’s side. With the key up A is the top terminal closest you.
To read ECM codes short terminals A & B together and turn the key to run, codes will blink thru the Service Engine Soon light. (Don’t start the car!)
Terminal F is used for some tests of the Torque Converter Lockup System. See the TH125 article for more information.
Terminal G is the fuel pump test point. It will have 12V on it whenever the pump is on. It can also be used to feed 12V to the pump to determine if the pump or the controls are a problem.
None of the other terminals are used during normal service routines so leave them alone. If you short them out you could do major damage to the ECM. (Only a few terminals in the ALDL are even wired.)
You can find the complete pin out of this connector and others here –> Fiero Tech Zone He also has a brief ECM code list.
There is a cheap tool to read codes in the tool section of most parts stores. It is a simple stamped metal item and cost about $2. You can also use any wire that will make snug contact.
If you have an Autozone store near you ask the counter man for the book and key to read the codes. The book is titled “What Does It Mean When Your `Check Engine’ Light Comes On?” This small book lists common codes for GM Ford and Chrysler and how to test some of the ECM sensors. The book is free.
The best tool for dealing with the ECM is a scanner. These tools read the full data stream from the ECM and will report data from sensors and how the ECM is reacting to it. The AutoXray GM OBD-1 scanner is one of many tools available and cost about $150-200. Other scanners are available but most cost more.

Notice! It is a violation of U.S. Federal law to remove, modify or disable emission control devices. Some states, like California, have laws above and beyond Federal regulations.
Fiero has very little in the way of emission control hardware. There is only the catalytic converter, EGR valve and a fuel vapor recovery canister. None of which require rocket science to fix. (In California nearly all parts of the engine are regulated. Make sure any aftermarket parts you install meet CARB requirements.) There’s also the PCV system. Almost forgot that one.

Catalytic Converter

The catalyst is used to burn off excess fuel and oil that escapes normal combustion. The catalyst usually fails in one of 2 ways. It either disintegrates or gets plugged up with soot. In extreme cases the guts can melt. (Usually if it disintegrates it blocks up the exit port.) The catalyst needs to be replaced when it fails. You can’t fix it.
You want to know which way it failed. If it fell apart then you can likely just replace it but if it’s blocked up with carbon or melted then try to find out why before you install a new one. If the motor is running rich, burning oil, or leaking coolant then these problems must be fixed before the new catalyst is installed otherwise you’ll wreck the new one in short order.
A quick way to test the catalyst is to measure backpressure at the O2 sensor port. According the June 2001 issue of Motor…
With the engine idling, the pressure will usually be below 1 psi on a good system.
Backpressure reading over 1.5 psi is cause for concern. Next, bring the rpm to 2000 and check the pressure again. A good system will usually show less than 2 psi. If the pressure is over 3 psi, the catalyst is most likely going south.
Of course most people don’t have the fancy commercial one of these lying around, but they can be made. You’ll want to use some metal or high temperature flexible tubing to keep the gauge away from the worst heat. You also want a gauge made for low pressure, something with a 5-10psi top end.
You can use an old O2 sensor or spark plug to fabricate the exhaust fitting.
If the catalyst croaks… Once the catalyst is off make sure it hasn’t blown its cookies down the exhaust pipe. With Fiero’s exhaust setup, you can probably suck the stuff back out of the muffler with a shop vac. (Empty the vacuum before starting so you can tell what came out of the exhaust.) If you don’t check for this you could fry the new catalyst. At the very least the exhaust will still be restricted and likely hurt performance.
Many people think the catalyst does nothing but rob performance. Once upon a time this may have been true but today’s high flow catalyst units present very little restriction of exhaust flow. In the vast majority of cases you gain nearly the same performance increase with a new catalyst as having a straight pipe.
·     A straight pipe may give a HP increase but can reduce low-end torque in many engines.
· A straight pipe on an engine with backpressure EGR may also cause odd problems. These engines must have some backpressure to operate properly.
It is illegal in some places to put used catalysts in the trash. Even when it isn’t illegal try to dispose of it at a muffler repair shop or some other place that will send them to be recycled. (They recycle both the metal and the catalyst material.)

EGR

Note! An altered or defective exhaust system can screw up operation of the EGR valve on the L4. How much depends on the specific alteration or defect.
The EGR, Exhaust Gas Recirculation, valve is used to limit emissions and to prevent engine knock. On V6 the valve is ECM controlled but on the L4 it is operated by a combination of engine vacuum and exhaust back pressure.
There’s not much to go wrong with the valve. It can jam or leak which is usually caused by carbon and rust in the valve base. The diaphragm that moves the valve can deteriorate and leak. That’s about it. (In one odd case, I had the return spring or something in the vacuum chamber broke.)
You have to watch that the valve is connected to the right vacuum source. That information is on the VECI, Vehicle Emission Control Information, label on the deck lid. Hooking it up wrong can make it open at the wrong time or not at all.
The main problems with this valve on the V6 are that the valve plumbing likes to crack and the ECM control solenoid likes to get trash in it. The cracks of course hurt engine performance, if the car even runs with these vacuum leaks.
The control solenoid can sometimes be cleaned but you have to watch what you clean it with. You want a plastic friendly solvent that leaves no residue or lubricant behind to collect more dirt.
If you suspect EGR valve problems, take it off and inspect it. The gasket for the L4 valve is only about $1.00. I imagine the V6 one is about the same. (FelPro gaskets…) Always install a new gasket if you remove the EGR. A small exhaust or vacuum leak can cause major hair pulling…
Carbon or corrosion on the valve can hang the valve open or shut. You may be able to clean carbon off with EFI system or Carburetor cleaner. Corrosion will usually mean valve replacement.
Shake the valve. Noise is bad… Nothing in it should rattle.
Push the diaphragm up. You may have to carefully use a tool of some type. (A stick of Plastic or Wood is probably safer than metal.) Does it move smoothly and return to the closed position by itself? If not the valve probably needs replacement.

When does EGR open?

That depends on the EGR in question. I can tell you when it should definitely NOT open. It should not be open at idle or at WOT. Otherwise… On the ECM controlled ones it will open whenever the ECM is programmed to open it.
On backpressure ones, like the Fiero stock 4 cyl, it will open at certain combinations of vacuum and exhaust pressure. Exactly when those conditions will be met is hard to say. It will vary based on the condition and configuration of your car and you driving habits.

Service Warning!

THIS APPLIES TO ALL VEHICLES FITTED WITH THE UNIVERSAL EGR VALVES.
Many replacement EGR valves are of the universal type and come with metering washers that are affixed to the valve prior to installation on the car.
These washers MUST be staked in place. Do not depend on the gasket to hold them. If the washer comes loose it will screw up the metering allowing more exhaust gas flow than it’s supposed to. The washer could even fall into the motor and cause major damage.
To stake them down place a punch or the corner of a chisel in the base of the EGR valve next to the washer seat. Hit the punch to dent the valve base and force metal toward the washer. Do this in at least 3 locations around the washer.
Record the number of the original valve to both the sticker included with the valve and a permanent location on the vehicle or in some other place you can find it again. The label often fades. You’ll need the number if you ever have to replace it again.
To select the correct washer you need the code stamped into the OE EGR shell…

Fuel Vapor Canister

The Fuel Vapor can is a little confusing for many people. It is simply a can of charcoal with a vacuum controlled air vent stuck on it. The emission control purpose of the canister is of course to prevent fuel vapor from leaving the gas tank but it also saves you money if it works right. Fuel that evaporates from your tank costs money and gives nothing in return. The canister catches this fuel and lets the car use it. It’s a small amount at any one time but over the life of a car it can really add up especially in hot climates. A canister that is working right will not hurt performance and will add ever so slightly to your MPG.
The Canister Purge uses two vacuum lines. The large one goes to manifold vacuum and carries the fuel vapor into the engine to be burned. The small one is the control line and goes to a port on the throttle body that opens upstream of the throttle butterfly. When the throttle opens beyond a certain range the purge control valve opens and allows manifold vacuum to draw the vapor from the can.
The only maintenance the canister needs is periodic checking of the vacuum lines and filter. There is a floss filter on the bottom to trap large dirt from entering the can and plugging it up. That filter needs to be kept clear of major trash and should be replaced once in awhile or when damaged. (The filter costs
about a dollar at Wal-Mart.)
There are only a couple things that can go wrong with the canister. It can be damaged by cracking the thing or by over filling the gas tank. “Topping off” the gas tank can force fuel up the vent line into the can and ruin it. While the fuel pump nozzle is supposed to shut off when the tank is full, they are often bad and can pressurize the fuel tank enough to force fuel up the vent. Certain types of “Vapor Recovery” nozzles are great for this.
The purge control valve can fail or its line can be connected to the engine wrong. Either can cause problems. The routing of these lines is also on the VECI label.
The fastest way to test for drivability problems caused by the vapor can is to disconnect and block both vacuum lines. If the problem stops, the vapor can is bad.

How does the canister work?

This explanation is based on an article from Motor Magazine or Motor Age that I can’t find anymore…
The canister is filled with high-grade charcoal similar to a gas mask. When fuel vapors expand out of the fuel tank, they cling to the surface of the charcoal.
The important thing here is that fumes don’t soak into the charcoal grains like most people think. This “small” fact is what makes the whole canister possible.
When the canister is purged fresh air is sucked thru the canister, which knocks the fuel molecules off the charcoal and caries them into the engine. Canister purge in older cars, including Fiero, is usually controlled by a ported vacuum signal from the carburetor or throttle body. In many newer vehicles the canister purge is controlled by the ECM/PCM.
If liquid fuel gets into the canister it will soak into the charcoal just like lighter fluid does in your grill. Once that happens the charcoal is ruined. Even if you could dry out the liquid fuel, the carbon won’t recover.

PCV system

The Positive Crankcase Ventilation system is both an emission control and a significant improvement to engine longevity. The job of the PCV system is to remove fumes from the crankcase and burn them. These fumes pollute the air and if not extracted from the engine they promote contamination of the oil and varnish on internal parts.
There are 2 major parts in the system, an air filter, and the PCV valve. Make sure both are clean and that the vacuum line(s) and vent hose are sealed.
The PCV valve should be replaced every couple years at most. There is a spring in the valve that is critical to proper operation. The spring will weaken over time. A bad PCV valve is hard to detect. The obvious test of shaking it only tells you it’s not stuck closed. It won’t tell you the spring is weak.
Make sure you clamp all the joints in the PCV line. The rubber parts can’t be trusted to seal themselves. Don’t over tighten the clamps or you will damage the soft parts.

Emissions Service Parts

Note: Be careful buying PCV parts for the 87-88 4 cylinder motors! Many parts books incorrectly list them as using the same parts as the older 4 cylinder engines. Double-check them against Grand Am or Olds Cutlass Calais of the same years.
I had a heck of a time finding the correct PCV filter for my DIS motor until I looked it up under the Olds line. I’ve noticed some parts catalogs also list ignition parts wrong as well.
This is a quick list of stuff I’ve seen listed and where. I’ve seen AC Delco emissions parts for DIS 4 at Parts America. I imagine they cover other years but I didn’t feel like checking them all. (I think the same vapor can is used in all Fiero.)
The part numbers for the DIS motor parts…

As far as I can tell, the AC EGR is an OE matched unit. (At least that’s the picture they have on their web site.)
GM Parts Direct lists the Vapor Canister for about $25. (Use GM # 17075840)
They don’t have the EGR valve.
No AC Delco part was listed for the one V6 I looked up. (86 GT) Because the V6 valve is ECM controlled it’s not as critical who made it as long as the new part is high quality and provides the correct gas volume.
If you can’t find a stamping number to use for universal EGR’s, try using the information listed with Niehoff Ignition’s parts. Here’s the info they list on Parts America for an 86 GT with their part # FE134A valve. (I’ve never use Niehoff stuff but there catalog info is handy. They are the only one I’ve seen so far that lists data like this.)
[E. G. R. Valve] OE Number 17085897; Orifice Number 11; Use EGR Valve Gasket {FE302}; Use EGR Tube Gasket {FE354}
Notice the OE stamping number above. You could use that bit of info for any universal EGR. (The one you have may use the same metering washer or a different one. Get that info from the chart that comes with the new EGR.)
The V6 EGR solenoid I found listed under “Vacuum Regulator Valve” in the Fuel Injection parts. Parts America says it usually ships in 5 business days.
AC DELCO 214-361 $102.99 [EGR Vacuum Regulator Solenoid Valve] GT, SE Listing
Everyone who’s got them likes Rodney Dickman’s catalyst kit. It has the needed stainless steel adaptors needed for installation.

4 cylinder motor mount

There are 2 kinds of motor mount available for Fiero 4 cylinder. (I think this applies to all of them…) You can get them solid or liquid filled. The solid is a little less expensive but the liquid filled is better at isolating vibration. Of the two, I prefer the liquid filled even if it’s a bit less durable than solid. Anything that reduces engine vibration traveling to the car body is a good thing. (The liquid mount is usually the easier one to find in stock.)

How do you detect a bad liquid filled mount?

In the drawing above I’ve colored the steel body of the mount green. Notice how the rubber passes over the safety pin. The motor bracket can touch the rubber over the pin but mustn’t compress it any significant amount. If the motor bracket is resting against the metal body or the safety pin then the mount is bad and must be replaced.
Note! It is entirely possible to get a new mount that is bad! When you buy a liquid filled mount, you should not hear allot of sloshing when you shake it. If it sloshes, it’s bad. Don’t accept it! (The mount will usually have a tiny air bubble in it but it shouldn’t slosh like a half empty soda bottle.)
A sloshing mount has air in it and won’t be able to support the motor. Once installed it should pass the above inspection, if not then take is back and get another.

Changing the Mount

You need a 15mm socket and a 15mm box end or flair fitting wrench. (I prefer the flair wrench. It seems to grip better.)
Disconnect the battery.
Disconnect one end of the torque strut. (Dog Bone)
Jack the car, install a jack stand, and remove the right rear wheel. The top nuts are easier to get if the wheel is off. (Yes, I’ve tried both ways… take the wheel off.)
Remove all four nuts from the mount. These are lock nuts and will need to be turned with a wrench all the way off.
Jack the motor up. Use a block of wood between the jack and oil pan. (If you don’t use the block the oil pan could collapse.) Keep the jack over toward the transmission to it will lift straight.
Pull out the old mount and clean the motor bracket. Don’t loose the top washers that are likely buried in crud.
The new mount only fits one way.
Put the heat shield, the nuts and washers back on.

Mount care

If you have a 4 cylinder using traditional spin on oil filters… (This isn’t an issue for filter in pan motors.)
When changing the oil, stuff a rag into the engine bracket to catch oil that runs down while you change the filter. If you can keep oil off the mount then it will last longer.
Consider making a shield for the mount out of some aluminum sheet and sandwich it between the top of the mount and bracket. This will help keep oil that runs down the bracket from pooling on top of the mount. Constant soaking in oil will shorten the life of the mount. It doesn’t matter much how you make it as long as it deflects the oil that invariably spills from the filters during changing.

Transmission and V6 Motor Mounts

These are solid rubber mounts and there’s not much to them. Most of the time you can easily see damage to a bad one. Sometimes the mounts tear away from the metal parts too cleanly to be obvious. If you think a mount may be bad and you can’t see damage, try gently jacking up whatever the mount supports.
Jacking will spread open any tears in the rubber. Don’t get rough with the jack or you could tear a good mount.
When ever you have to replace a mount make sure you loosen all the others.
That way the mounts can all settle into position without loading.
Except for 86.5 and later 4 cylinders with automatic transmission, you’ll almost never see just one mount that is bad. The front mounts and the dog bone are the most likely to fail but it’s entirely possible for all of them to be bad. (The 86.5 and later 4 cylinder/AT setup only has one engine mount and one transmission mount. Read the torque strut article for more info…)
Oil soaked mounts may not be torn but are probably considerably softer than they should be. Oil and other chemicals break down the rubber over time.
Always clean off any oil that spills on them.

Polyurethane mounts

Polly mounts are generally perceived as better than OE style vulcanized rubber mounts. In some applications they probably are but for general use they simply aren’t needed and are unlikely to do anything performance wise for the car.
Depending on just what ones you buy, many OE style mounts are stronger than the ones that came with the car.
Polly can also pass more vibration to the car, especially at idle in automatic transmission cars. (This has been proven with polly dog bones. The 4 cylinder motors are the worst for this.)
Polly mounts can add some color to the engine bay. They may tolerate the heat better.
They are more resistant to oil grease and other chemicals, which shouldn’t be much of an issue. The mounts shouldn’t be getting allot of stuff on them in normal use. The main source of oil on mounts is usually a sloppy oil change or a leaking gasket. Rubber mounts usually last years in even the worst environments.

While this article was originally written for Fiero 1987-88 L4, it applies to all vehicles with self tensioning serpent belt systems.
WARNING: Do not assume that the belt listed in the catalog fits your engine! If the belt forces the tension assembly out of range you can and likely will break things.
WARNING: NEVER force the tension assembly! If you don’t break it instantly, it probably won’t last long. Most tension assemblies have internal stops. IF the tension assembly is actually binding, replace it ASAP or you will find yourself stranded someplace, likely someplace nasty, in the near future.
DO NOT start a car that shows the tension assembly out of range! You will not be able to exchange the belt once you run it even a few turns. Running the belt WILL NOT make it fit. (You also want your hands and the pulleys clean as most stores won’t exchange a filthy item.)
As many of you may have noticed the serpent belt setup used in the 87-88 4 cylinder cars is not well covered in the Haynes or Chilton’s books. (At least not that I’ve ever found it.) The belt is easy to deal with as long as you keep a few things in mind.
The Fiero 4 cylinder Serpent belt requires no adjustment. Belt tension is controlled by a spring-loaded arm.
The one tool you should have is a “serpent belt wrench.” You can do without this tool but it usually means yanking the battery to get enough room to rotate a socket wrench. The belt wrench is made to fit into the confined space in Fiero and other such cramped cars. It’s worth the extra cash. ($15-30 US, shop around.) These are cheap enough that you can bend them for a custom fit to a given car, tho I think you will have to heat them to bend them.
To unload the belt tensioning arm put a 15mm wrench on the Idler Pulley bolt and rotate the wrench toward the battery. NEVER attempt to remove or rotate the bolt in the center of the spring arm!

Things to remember about serpent belts.
(Applies to all cars with serpents.)

• When properly tensioned Serpent sets will always out perform V-belts. This is why nearly all Serpent sets use a spring tensioning device. (See note at bottom.) It is critical the belt tensioning device work properly or belt life will be shortened tremendously. Because Serpent sets are carefully calibrated, life of PTO devices is also improved. The alternator, water pump, etc, are all protected from running with an over tightened or loose belt, which protects the bearings and sheaves from excess wear.
• These belts HATE oil grease and coolant. You’ll eat one up in short order if you get one contaminated and don’t clean it off. If for example you spill oil during an oil change and it gets on the belt or a pulley you must clean it up. To fully clean it up take off the belt and wash everything in citrus base cleaner or Simple Green. NEVER use parts washer or other solvent on the belt. (Brake Parts Cleaner will work well on the pulleys.) If you don’t get this mess cleaned up then the belt will glaze and start squealing. Once the belt squeals it must be replaced.
• Make sure the belt is running centered on the Idler pulley. In Fiero this is the smooth pulley that runs on the backside of the belt. If the belt is running off the edge of this pulley then the spring arm has likely gone bad and will have to be replaced. The spring arm cannot be serviced. (Only the bearing in the idler pulley can be replaced.)
• On some cars the Idler may be grooved and other pulleys may be smooth. All the pulleys must line up or you’ll eat belts. (The FWD applications of the 2.5 often have a smooth water pump pulley.) The belt must never be allowed to run off the edge of a pulley.
• Whenever the belt is off carefully check the bearings in the idler pulley, water pump, and alternator. (If present check the AC compressor.) If the bearings are sloppy, rumble, or feel “dry” as you turn the shaft then you have other problems besides the belt wearing.
• When installing the belt it helps to have someone under the car to hold it on the crankshaft and AC pulleys. These are hard to see and new belts tend to have a mind of their own about staying on them.
• On Fiero L4 and some others… Slip the belt over the smooth tension pulley last. Let the belt lay between the pulley and the wrench until it is around all the gooved pulleys.
• Keep an emergency belt and the wrench in the car at all times. For an emergency belt I recommend using the belt for cars without AC, even if the car really does have AC. This belt is easier for one person get on from the top with the least amount of mess. It will also give you backup if/when the AC compressor fails and cooks off the belt. (With the age of most AC compressors the chance of this is pretty high.) You can drive a car w/o AC but not a water pump or alternator. (It depends on the car. Fiero 4 cyl’s can be run with either the AC or non AC belt. Some cars can’t do that trick.)

Side note: Some cars use serpent belts in place of V belts, and also tension them the same way by adjusting either the Alternator or AC compressor. It is critical that these applications be correctly adjusted or the belts will not last.
Serpent belt material is much more picky about tension that V belts.

Belt Map

For those people that don’t have the belt map on the deck lid…

Why Does My Belt Keep Failing?

The first thing to check is pulley alignment and operation of the tensioning device. A critical factor here is that pulleys that are close together tollerate much less alignment error than pulleys far appart. An AC equiped Fiero will eat belts very fast if the crank, AC and Waterpump pulleys are just a little off. A non AC Fiero can take a more error as all the pulleys have longer belt runs.
Make sure every pulley is clean. Make sure nothing is packed into the grooves or built up on the peaks. Packed dirt will make problems.
Is oil or coolant getting on the belt? That will kill it fast.
How are you cleaning the car? Some cleaning and most wax products are bad for the belt. Fiero’s vent grates allow such products to easily find their way onto the belt. It wouldn’t be a bad idea to throw a cover over that side of the engine to prevent car wash products from getting on the belt. (Make sure the cover can’t contact hot exhaust parts! Remove the cover as soon as you are done washing!)
Check the AC compressor! If there is any missing or loose hardware, the compressor will move and alter the pulley alignment. Any alignment error will greatly shorten belt life but it is even worse with a high load item like the AC.
The belt’s life will be affected by the high heat in the engine bay. Depending on the setup of the vent grates, and a few other things, the belt may not last more than a year or two even if everything else is perfect. My experience, even with Fiero’s hot engine bay, is that the belts will last several years unless the pulleys have problems.

Checking Belt Tension

This works for most spring tensioners and will check your belt length as well without measuring anything.

• On the big round end of the arm where the pivot and spring are, there is a small arrow. It is hard to see and is often just a small triangle.
• On the arm mount, there is a gauge area. This often looks like V*******V or it may be a simple raised/indented bar on the metal. It can be hard to make out too.

Both marks are usually on the top part of the tensioner’s pivot area and shouldn’t be hard to find
once you clean the dirt off.
The image left shows the actual scale on an 87-88 Fiero L4 tensioner assembly. A new belt should have the pointer on/between the closer marks. (These marks will be slightly toward the front of the car on top of the tension assembly. The bolt hole you see is by the water pump.)
The pointer on the arm must be within the gauge area on the bracket. If the pointer is not in that area, the belt is not at the right tension and probably will not last long. Ideally the pointer should be in the middle of the gauge. If it is right at the low limit, the left end of the scale in the image, then it will probably move out of range as soon as the belt wears in some. Frankly If the belt is even close to the low limit, you want to replace it. Either it is very worn or significantly too long.

This belt doesn’t fit, the Catalog must be wrong…
If you can’t get the catalog belts on a car with a spring tension setup, you could have a few things besides a wrong belt. For the 87+ Fiery L4 here are some of the most common listings:

• Fiero 2.5L with AC: K060660 (Gates) 660K6 (Drive-Rite) 5060660 (Dayco) 4060660 (Goodyear)
• Fiero 2.5L no AC: K060615 (Gates) 610K6 (Drive-Rite) 5060610 (Dayco) 4060615 (Goodyear)

The Gates Goodyear and Dayco numbers are direct from their online catalogs.
Drive-Rite, a Dayco brand, is from PartsAmerica.com Oddly the Drive-Rite and Dayco cross references to Gates K060612, which is .29 inch shorter than K060615.
There is some tolerance in the system for variations in length. As long as the tensioner stays in the proper range, it doesn’t matter if one catalog says a hair longer/shorter than another. If you put a belt on that is at the bottom limit new, it could get out of spec once it runs in so make sure you check it after a few hours running.
Warning: The belt should easily slip onto the Idler Pulley on the Tension Assembly.
You should never have to fight a belt onto the idler. (Or whatever pulley goes last on other engines.) At the same time when you let off the idler, the idler should keep it tight. (Duh.) The range of acceptable belts is fairly small.
If the listed belts won’t fit, the first thing to check is the number printed on the belt. It’s not uncommon to have the belts get in the wrong package. The sleeve packing many companies use can fall off and sometimes the parts store or distributor puts the wrong belt back in the thing.
If you got the listed belt ok then you could have a bad belt tension device.
These often bind up with age and you may not be able to move them far enough to mount the belt. Don’t use a longer belt to get around this. The longer belt probably won’t be tight enough and could fail really fast. Go by the scale on the tension assembly! If the pointer is off scale the belt is too short regardless of catalog listing.
You could also have a replacement alternator or other device with the wrong size pulley. This is very common and why you need to check the pulleys on replacement parts. A small change in any one pulley can result in a belt change of an inch or more depending on the pulley size and how much belt wrap it has.
If a pulley has changed, it could cause you other problems. If the alternator is spinning too fast or slow there can be trouble. (Read Watt Story for more on that.)
There is some variation between how belts sit on the pulleys. This can be from one brand/type to another or even from one batch to another.
You may also suffer from “tolerance stacking.” In this case slight variations in mounting of the driven devices can require a slightly longer or shorter belt on the system. The alternator, AC compressor, waterpump and so on have some slop in their mounts. Over time and various parts replacements these parts may be in slightly different locations than original. These changes can add up in ways that make the belt path longer or shorter than the vehicle maker called for. The catalogs all list only what the vehicle maker said fits.

How serious is correct belt fit?

If you want to avoid this…

Make bloody sure that the tension assembly’s pointer is on the scale. Most if not all tension assemblies will not tolerate being pulled over range. If the pointer goes off scale low, the belt can go completely slack and be thrown from the engine.
To be more annoying… You won’t know until you try a given belt. There is enough variation that a 66 inch belt from one maker will sit a little differently and be ok while another doesn’t fit. Belt route will also be a factor. Bypassing the AC on the Fiero L4 can make it so all the 61 inch belts fit even when you have problems with some 66 inch belts.

How do I read a belt size?

The last or first three digits of the belt size tell you how long it is in inches and tenths. A 660K6 or x060660 (x varies by brand/type and isn’t very important.) is 66.0 inches long. The next two sizes larger are 665 and 670. 66.5 and 67.0 inches. (In my case the 670 belt has the pointer just a hair above the “middle” mark on the scale.)
An important note… The sizes that end in 5 are not always exactly .5 inch.
Dayco 5060665 is actually 66.6 inches according to Dayco. That means you need to check belt specifications.

Tension Assembly Replacement

Replacement assemblies should come with a gasket on the engine side. If the gasket is missing, you will have to make one. The gasket needs to be 3/32 inch thick. RTV Silicone WILL NOT work in this application!

1. Drain the cooling system. (The arm unit forms a cover on the front of the water jacket.)
2. Disconnect the battery and remove it.
3. Remove the top alternator bolt. (You may want to loosen the bottom one, the new tensioner may not line up exactly.)
4. Remove the Idler Pulley from the old and new tension assemblies.
5. Remove the old tension assembly and install the new one.
6. Replace the Idler Pulley on the new Tension Assembly.

If the new arm comes with a cork gasket then paint the gasket with Permatex High Tack, Permatex Super 300, or Balkamp Aviation sealer. This will fill any pours in the cork. A VERY THIN film of RTV Silicone will work if that is all you have handy. Make sure the whole area of the block covered by the arm base is clean before installing the new arm. If you pinch something between the arm and block you will likely damage the new arm or prevent it from sealing.
The new arm provided by Pontiac is built a little better than the original one.
You should only have to replace the part once in the life of the engine. (Keep in mind, because this arm is a cover on the water jacket it is exposed to full operational heat of the coolant. The old grease in the arm didn’t hold up well, and that results in pivot wear.)

Why Is There a Hole In My Block?

The large hole in the 4 cylinder that is covered by the serpent tensioning device is the opening for the water pump when this block is used in other vehicles. In most FWD versions, the hole has a steel cover bolted over it. The only variation I’ve seen use the hole is the S-10 truck. (I’m not sure if S-10 is exactly the same block or not.)

The TBI used for 87-88 Fiero 4 cylinder motors is the 700 series unit presently manufactured by Delphi Automotive for GM.
You can find Delphi’s public relations info for the 700 TBI here. The information includes images and general specification data. The articles that we’re interested in at the moment are “Throttle Bodies - Single Point” and “Throttle Bodies - Multec Bottom Feed.” The first is the TBI unit and the second is the injector in more detail. Fiero uses the low-pressure version. (Note: Delphi changes things fairly regularly. If they still exist, these documents may be hard to find. I can’t post them due to copyright.)
Below you can see how the TBI is setup and where some of it’s components are.
I also noted the MAT sensor for you. (MAT is also covered in the DIS article.)

• FPR, Fuel Pressure Regulator
• TPS, Throttle Position Sensor
• IAC, Idle Air Control motor
• F In/Out, Fuel Lines
• MAT, Manifold Air Temperature

The design of this TBI is really something. It can tolerate amazing amounts of crap in the fuel system without plugging the injector. There are screens right on the injector. You’d have to cover them nearly completely to block off injector flow. To get that much trash to the TBI, both the main filter and the pickup sock in the tank would have to fail or you’d have to have major corrosion damage to the inside of the fuel lines.
The 700 TBI is comprised of two modules. The upper section handles all the fuel metering and is the same regardless of what lower section is used. The lower section handles all the air metering and contains the throttle plate and IAC. There is no fuel flow between the modules except what flows from the injector tip. 700 TBI bore diameter is determined entirely in the lower section.
(If you were punching out a 700, you would only machine the lower half. The lower section, assuming there is enough metal, can be punched to the maximum diameter of the upper half.)
BTW, the TBI used for 87 and 88 Fiero L4 has a 45mm diameter main bore. The largest Delphi makes is 48mm. You could install a 48mm one but you’ll need to ream the manifold and you probably won’t gain much power.

Do I need to use injector cleaner in my gas?

Probably not. The cleaners already present in most pump gas should be more than enough. Keep in mind that this injector is not being heat soaked like port injectors are after engine shutdown. It’s far from the intake valves and upstream of the throttle as well. That prevents fuel residue from cooking onto the injector.
The only time I can think of where cleaner might help is if the car sat parked for a long time. That should help wash away anything caused by stale fuel.
With this system, if you are finding allot of carbon in the TBI and intake then you have problems developing that need more than some cleaner. (You will likely also need to check/replace the MAT sensor.)

Throttle Position Sensor

The TPS is not adjustable. The ECM is programmed to accept any slight variation in the home position of the sensor and recalibrates the home position each time the engine is started.
The TPS does wear over time, but it should last many years under most conditions.
Do not attempt to clean the sensor and never spray it with solvents or pressure washers.
The easiest way to test the TPS is to use a sewing needle to probe the terminals. It’s long and very thin so you are less likely to cause a short if you slip. Simply slip the needle between the wire and the seal. If you short the terminals to anything you could fry the ECM!
One terminal will show 5V. Another terminal is ground. The last is the output.
The TPS output should show less than 1.25 volt when the TBI is at idle. Output voltage should increase smoothly between idle and WOT. (Note: It is usually easier to test the sensor with an analog meter. Digital displays are often too
jittery.)

The Injector

Note: Don’t rely on the visual appearance of the injector output. In most cases you won’t be able to tell a good spray amount/pattern by eye. These systems nearly always look like shower heads when running. Keep in mind that unlike port fuel injection, fuel from the TBI has plenty of time to mix on the way to the cylinders. The TBI is also on a heated manifold just like a carburetor uses.
If the injector is leaking it will tend to do that as soon as the system pressurizes. The most common leak is O-ring failure but it is possible for the injector to leak internally.
The injector used in these is built like a tank. I don’t think I’ve heard of more than one or two that was actually bad. I’d say 99% of the time if the injector weren’t firing that you need to check the fuel pressure and the signal from the ECM.
If the injector is leaking, make sure it’s not one of the two O rings. The O rings are more likely to fail than the injector. If the O rings are bad, then I’d rebuild the TBI and replace all the other stuff as well.
There are test (”noid”) lights for the injector used in the 700. Use them! A single noid light costs around $6 while the injector costs $75 to $100 or more.
You can get noid lights at many parts stores. You can get whole sets of them online from various sources.

Idle Air Control motor

Contrary to popular belief the IAC is very well designed and will last nearly
forever under most conditions. If you think there is an IAC problem your first project should be checking for vacuum leaks and EGR problems.
DO NOT spray the IAC with “carb” cleaner. If you must try to clean it, use electronics parts cleaner. Strong solvents can eat the insulation off the coils.
You can now get test (”noid”) lights for IAC as well as the injector. I’ve seen these for about $10 at Pep Boys.
Ideally, you’ll use an IAC noid with an ECM scanner. The lights on the noid should match whatever the scanner says the ECM is doing. The quickest test is to plug in the noid light and create a small vacuum leak or turn on the AC. (If the AC works…) Either one should cause the ECM to try to adjust the IAC. Even simply moving the throttle some should create an IAC change.

When does the IAC reset?

Per GM service documents:

The IAC valve will be reset by the computer when the vehicle speed exceeds 43 MPH while the engine speed is above 2000 RPM.

Or

When the diagnostic test connector is grounded when the engine RPM is above 2000 RPM.

Fuel Pressure Regulator

The fuel pressure regulator is very unlikely to fail. If/when it does, it usually leaks externally. It could be possible for something to get trapped in the regulator and hold it open. Corrosion of the regulator valve and seat are unlikely. They appear to be Stainless Steel. Keep in mind that if you remove the regulator that it may not seal reliably when you put it back on. Do NOT use gasket sealer on it! If it leaks then it needs to be replaced.
The fuel pump on the other hand is a common failure item, especially if you’ve run the tank dry. The fuel flow cools the pump and it won’t take long to cook when running dry. (This is true of the many kinds of pumps, not just fuel pumps.)
The quick test for no or low pressure is to pinch the fuel return line and see if you get pressure. This may help if the regulator is blocked open but probably won’t do a thing if the pump is batty.
There is a fuel pressure gauge set available for TBI and other low-pressure systems that don’t have Schrader valves. The set includes and adapter that save you from cutting the line to install a T. These sets are expensive, typically over $50. You may be able to borrow one from some parts stores. (The expensive part is the adaptor that installs between the fuel line and the TBI body so you can connect the gauge.)

Fuel Filter

It’s under the car and can be a real pain to change.
You want to change this every so often, like once a year or so. These filters are built like a small oil filter internally and hold a tremendous amount of garbage.
The only way I can think of that you could plug the thing are if the fuel line is going bad or if the pickup sock in the tank fails. If you seem to loose fuel pressure after the car runs for a while, the filter could be the problem.
If you are going to remove the filter for any reason then just replace it. They don’t cost very much and you can usually get them even cheaper at places like Wal-Mart.

Repair & Rebuilding

When installing the IAC motor, make sure the pintle is retracted. DO NOT force the IAC motor into the throttle body! If the IAC motor will not easily seat fully in the body then the pintle is too far out. You should be able to seat the motor fully into the throttle body with little effort.
Carefully check the TBI mounting holes in the manifold. These holes can be damaged if the air cleaner has impacted the trunk wall. (Read the torque strut article.) If the holes are stripped you’ll have to use Helicoils on them.
If the throttle shaft is badly worn, find another TBI unit. You should be able to find these fairly easily at any salvage yard. Otherwise the 700 unit is very easy to rebuild.
Don’t mess with the idle stop during rebuild! There’s no reason to fool with it.
The rebuild kits include the fuel pressure regulator diaphragm. If the FPR diaphragm is bad then just buy the rebuild kit and be done with it. The kit isn’t that much more than buying the diaphragm and you get all the gaskets, O rings, and screens. You essentially end up with a new TBI unit.
The rebuild kit usually comes with more gaskets than you will use. The last one I bought came with three mounting gaskets and two body gaskets. You should use the replacement gasket that matches the original.

Assembling and Mounting the TBI

When you put the two halves of the body together torque the screws to specification.
After you torque the mounting bolts, check the body screws again and torque as needed to reach specification. The mounting bolts often cause the body bolts to loosen. If you don’t check them the upper body could warp and cause an air leak.

(Source: ALLdata)
In case you don’t have a VECI label on the deck lid… Here’s how the vacuum lines connect to the 700. (It’s a photo of my VECI label that I was farting around with.)

Documentation

The 700 TBI is not covered in the Haynes Fiero book. Haynes does cover the 700 in their 86-96 Fuel Injection book. (Haynes # 10220) This book covers both versions of TBI used in Fiero. Amazon lists the book as out of print but it can still be found in many part store inventories.
The only other book I know of that documents this unit is the Helm shop book.
While expensive, these books cover all the year specific items left out of Haynes and Chilton. They also carry replacement Owners Manuals and other info.
ALLDATA DIY is a good source. This is the online version of the CD/DVD product they are well known for. While you can work directly from their data, I usually consider them a supplement to other sources, including the Helm book.
ALLDATA has all the TSB and Shop Manual updates you just can’t get anywhere else. If the online version allows printing, I’d say join them for a year and print everything you can get your hands on. (I strongly recommend a laser printer over an ink jet. Most ink jets are likely to eat multiple cartridges doing this.)

Adjustment Procedures

The only adjustment possible on the 700 is to the idle stop screw. With the possible exception of new replacement units, there is no reason I can think of that you should ever adjust the idle stop. All the ones used on 2.5 liter motors should transplant without changing the idle stop.
The only reason I’m covering the idle stop adjustment is because every so often you run into a motor where some hack has screwed it up. You’ll know if that’s happened because the Idle Stop seal will have been removed.

Idle Stop

You’ll need an ECM scanner to verify the IAC position.

1. Jumper ALDL terminals A & B.
2. Turn on key and wait 30-60 seconds. This will close IAC pintle.
3. Unplug IAC while key is still on.
4. Turn key off and remove the ALDL jumper.
5. Start car and set idle stop screw.

The Haynes EFI book says set the idle according to the VECI label, but of course the VECI label doesn’t say anything. Near as I can tell… If you set the Idle Stop for about 800-850 RPM then the IAC should be able to do its job properly.
Once you are done, shut off the car, plug the IAC in, and clear any errors that may have been set in the ECM.

Performance

This section is mainly a bunch of pondering. I’m still looking into most of it. I thought I’d put in what I had in case it’s useful to someone who wants a bit more power from the DIS motor. (It could also be useful to someone replacing a fried DIS motor…)
As I mentioned above, the Fiero TBI has the 45mm main bore. You might be able to find a 48mm unit to install. How much power you’d gain from that I couldn’t say but it’s something to keep in the back of you head if you are building up a DIS motor. It may be possible to bore out a TBI unit but I wouldn’t hold me breath on it. It’s not something you can do without a good machine shop.
If you do go looking for a 48mm unit, check the intake manifolds and head of later model DIS L4 as well. This could save modification of the stock manifold and may give you larger intake runners etc.
The reason I say this is that GM specified the 91 Olds Cutlass Calais (VIN U?)
Iron Duke at 112HP. I’ve seen that motor once and only externally. It looked identical to the 1988 engine. (Balancer motor.) They had to ring out the extra from someplace.
In reality, you’d be better off seeing if the 1991 engine would work in Fiero and then building that up if needed. That gives you an engine 5-6 years newer as a base. I couldn’t see why it would not but I haven’t been able to really dig into one yet. You should be able to get one for about $200-300 from a local salvage yard. (I believe 1991 was the last year for this engine.)
If you do that, make sure you also get its ECM! The PROM chip has information in it that may be needed. I’m pretty sure the thing still uses the same ECM as Fiero. Assuming the ECMs are the same, the VSS flag in the PROM isn’t. You’ll have to trick the ECM or burn a new PROM with the correct VSS flag. (You could just use the Fiero PROM but you’d loose updated code in the 91 PROM. The original Fiero PROMS have a few minor issues…)

Fuel Pressure

According to what I’m told, you can make the fuel pressure regulator adjustable. If you try this, do it to a spare regulator cover. It involves cleaning out the sealer/solder over the regulator screw. You may also need a longer screw and a jam nut to prevent the pressure from changing due to vibration.
(Someone in the forum did this once. I forget who…)
To tune it, you’ll need a fuel pressure gauge and a chassis dyno or a Gtech unit
You really don’t want to do this by feel alone.
The idea is to start from OE pressure and tweak the thing up a little bit at a time until performance peaks. (It’s a bit more involved than I’m covering here.)
Keep in mind that if you restrict fuel flow too much you could burn out the fuel pump!

4 Cylinder Timing Gears

NOTICE! This is an unfinished document. It is a collection of all the stuff I’ve come up with tested or not… USE IT AT YOUR OWN RISK!

Anywho…

Cam jobs suck under the best of conditions. The majority of FWD and Fiero cams are never fun to work on. Here’s a collection of stuff I’ve gathered up that should help.
One item that surprised me… GM actually built the 87+ 4 cylinders with a simple steel crank pulley. As cheap as GM is, that one was still surprising.
Harmonic balancers are usually considered a critical part of the crank set. The good news is they did revise the parts list and you can get a real harmonic balancer for them.
I’m working on methods for changing the cam pulley using common tools. I’ve included that material here even though it’s only in the development phase. I figure there’s enough there that more advanced people can use or adapt it as needed. I’m sure there is some kink in it that still needs a good beating.

UPDATE

Back On Holiday has posted a large number of pictures he shot while doing his timing set.

• Here’s the original Forum Thread. This thread has grown to 2MB plus in size and may be difficult for some readers to download. (IE Users, Right Click stubborn images and then click Show Picture.)
• I’ve created a compact version of the thread here. This version is less than 800KB.
  • The images are smaller and I adjusted brightness and contrast to expose more detail.

I’ve also consolidated the GM parts listed here and in the forum. You can get them at GM Parts Direct. (This table doesn’t include Vin U parts.)

Source: GM Parts Direct. Prices as posted 12-Mar-02.
I recommend a new thrust plate anytime the gears are replaced. A crappy thrust plate isn’t going to help your new gears any. For less than $6 it’s cheap insurance.
It appears that the newer thrust plates have added holes to help with oil distribution in the hub area. I don’t know if the hole in the oil gallery plug is still needed with the new thrust plate. I tend to lean toward adding the hole because it should also get more oil to the gear teeth. I don’t think the revised thrust plate would help that.

Revised Parts

Quite some time ago, GM changed the timing gear numbers from individual parts to mated sets. If your 22P book or other old list shows them as separate parts, those numbers are invalid. Always replace the timing gears as a set no matter where you get them! The crank gear may look ok but even subtle wear can cause a problem with a new cam gear.
GM revised the crank pulley on later model 2.5l. The original is simply a steel pulley with no harmonic balancer function. In Fiero this applies to the 87-88 4cyl. I’ve also included the U VIN version of the 4 cyl for those that may have acquired one thru an engine swap. [My notes in square brackets]

“It is also recommended that a crankshaft torsional damper [AKA Harmonic Balancer] be installed along with the [timing] gear set. The damper reduces critical crankshaft vibrations thereby decreasing [gear set] wear. When the new damper is installed, the old crankshaft pulley may be discarded. If the engine already has a damper, it should be reinstalled.”

Source: GM TSB 90-6-21, Dated 02/90, Servicing Camshaft/Crankshaft Gears (Install Torsional Damper)
I’ve given both the GM timing set number and the damper number. I don’t know what the damper costs from the dealer. I have found it in inventory for the 87+R motors, so it’s still out there. I’ve also listed 3 third party replacements at the end of this page.
Harmonic Balancers are just plain good for the motor. They reduce timing gear and crank bearing wear and may give slight improvements to fuel economy and HP. Installing the new balancer is strongly recommended.

Fiber (Phenolic) vs. Metal Cam Gear There is a ton of debate over replacing the Phenolic cam gear with a solid metal one. While many people say a solid metal gear is better, I have my doubts.

Here are a few things to think about…

Various types of composite gears have been used in timing sets since at least the mid 60’s that I’ve seen. They may go back further than that. My 1968 289 Ford motor had a nylon tooth driven gear in it’s chain set. There’s allot of well-established technology behind using these gears in the Fiero motors.
The original Phenolic cam gear is lasting well over 100,000 miles and a dozen or more years in most cases. The odds are good the next one will outlast the rest of the engine and for many people, the rest of the car.
If you think 100,000 miles is too short a service life, consider that most timing belts in other motors have to be replaced at 40,000-mile intervals. Such belts are often as difficult or worse to replace than the “Iron Duke” timing set.
If/when the timing set fails in this motor; there is no significant damage to the engine. This is much different from many other motors where timing set failure can literally destroy the engine. Such “Interference Engines” are known for snapping valves and driving them thru the head block or pistons.
Phenolic gears have inherently smoother teeth than metal gears and generally stay that way over their life. This is another factor that allows tighter tooth clearance than metal on metal. Remember, gear teeth are by nature also bearing surfaces. The smoother they are, the less friction they develop.
Metal gears are prone to galling if tolerances become excessively tight or they aren’t getting plenty of oil. This can result in sloppy timing or even gear failure.
Part of your decision should probably include which engine setup is in the car.
Flat tappets will put more loads on the cam than Roller lifters will and that might shorten the life of the Phenolic gear.
The distributor will also increase cam gear load. Even in the distributor motors the Phenolic gear has been lasting 100,000 miles or more. In most cases, by the time the motor wears out a second gear it’s going to need a full rebuild.
Some people have indicated metal may be more noisy. If the gears are well made this should not be much of an issue. This is a helical cut gear. Such gears have more than one tooth in contact at any given time. This makes the transition from tooth to tooth much smoother than with straight cut gears.

What kills the gears?

Obviously simple wear is a big factor. The lack of a harmonic balancer on some versions of L4 could also be an issue.
As originally installed the gears apparently don’t get a large amount of oil. GM recommends a change to improve gear oiling. I strongly recommend that change be done. As I understand this, the only oil the gears get normally is whatever runs from the cam and crank bearings. The change punches a small hole in an oil gallery plug to get more oil to the gears.
Frequency of oil changes and choice of oil are also likely factors in this. If the gears are running a little dry to start with then crappy oil won’t help any.
Running heavier oil than specified could also be a problem. Heavier oil could increase oil pump load on the cam and reduce oil to the cam and gears at the same time.
When the cam gear fails other items to watch out for are the oil pump and, in the older motors, the distributor. Make sure you check both items when changing the gears. If either or both are binding then you could be overloading the cam gears. Installation of metal gears may only hide such a problem until the offending part(s) fail completely.
The endplay on the gears is also important. Too much and the cam could wander in the bore. Too little could make the cam bind. This item is very important to watch when changing gears.

Do I need to remove the oil pan?

NOTE: To clarify, Yes, I think you should probably drop the pan. Besides cleaning it out, you can check for pump problems before they kill the new gears, or worse. Interestingly, the GM gear change TSB doesn’t require this.
It’s a good idea but I don’t think most people do it. Also depends some on just how much was chewed from the gear.
Since the engine quits as soon as the cam gear does, allot of the waste is probably sitting right below the gear. Once the cam and crank gears are off you can probably get most of it out that way.
The big pieces of phenolic tend to sink to the bottom of the pan and sit there but if you think you’ve got allot of small particles you may want to do the pan.
At the very least, I’d change the oil after you fix the gears. You could use some kerosene to wash stuff into the sump that you can’t get out by the crank.
Changing the oil should remove anything that floats.
I also recommend a magnetic oil plug to help grab any metal from the drill and tap operations that may escape the rag. (I always run a magnetic plug.
Whatever it catches is that much less that passes thru the oil pump.)

Do I need to remove anything else?

Disconnect the battery cable(s), and if needed the dog bone. You don’t want to risk tugging the battery if you drop the motor any. The dog bone has to be loose to drop the cradle or remove the motor mount.
You may want to take out the strut and hub assembly to gain workroom. As long as you don’t separate the hub from the strut you should not need an alignment much if at all when you are finished.
You’ll probably want the mud skirt removed.
You can gain a couple inches by removing the motor mount. Just make sure you don’t rest the motor on the crank pulley. This may give you enough room for that you don’t need to drop the cradle.
To remove the motor mount, I reach in from the wheel well to get the top nuts. You can get one nut with a socket wrench but the other doesn’t have room. I use a 15mm flare fitting or box end wrench on that one. These are locknuts so they are going to be tight all the way off and back on.
You can gain more room by dropping the back of the cradle a little.

Remove and Install

Whenever the timing set is replaced, replace the crank seal while the timing cover is off. If the sealing area of the existing pulley or balancer is scored,
replace it or install a repair sleeve. (Clean all parts with alcohol or brake parts cleaner before installing the repair sleeve.)
Always replace the crank seal when installing a new damper!

Modified GM in car method

Please Note: This procedure should be considered “under development.”
Until I can obtain a test cam and gear, or (GAG!) my gear fails, I can’t test this. So while it should work, and it is based on a GM TSB, I just don’t have all the facts.
Based on a method originally published in GM TSB 88-6-62 dated 6/88, this version has been modified to allow common tools. (The original GM TSB is available by subscribing to ALLdataDIY.)

The logic behind this

GM’s method uses two 1/4″-28 bolts threaded into the metal hub very close to the cam and the PFKB method farther down appears to thread the access holes in the cam gear. I don’t see why a standard puller, used in close to or even partly biting the hub should be any problem. (The big holes allow access to the thrust plate that keeps the cam in place)
The Lisle steering wheel puller may even allow you to use GM’s recommended pulling bolt size and locations. You’ll probably need washers for the bolt heads.
GM has you start the holes with a small bit, enlarge them to the tap bit, and tap to 1/4″-28 with a blind tap. I forget how deep the holes are supposed to be.
They don’t go all the way thru.
The most important item is making sure GM guidelines are followed for the cam hole. If the hole is too deep you could weaken the cam. Too shallow and you may not have enough bite to press on the new gear.

Things you need

This procedure requires a high-quality steering wheel puller such as Lisle’s #45000. Cheap pullers may be destroyed in this application. You may be able to use a small harmonic balancer puller. (Lisle’s puller lists for $16.95. How much cheaper can you get and still have a good tool?) Don’t forget to oil the puller’s drive bolt before you start! (This version assumes you will use the Lisle 45000 puller. If you use a different puller you may need a different drill and tap to match your draw bolts.)

The Lisle 45000 puller contains the following parts:
45020 Puller Screw
45050 Screw Pad
45090 Puller Frame
(2) Washers
(2) 45200 3/8″ - 16 Bolt
(2) 45210 5/16″ - 18 Bolt
(2) 45220 5/16″ - 24 Bolt
If you can’t find Lisle tools at your local parts stores, try Sears. My area Sears had a bunch of Lisle stuff in stock when I was there last. (Don’t go by Lisle’s dealer list. Allot of parts stores buy from jobbers and often aren’t listed by Lisle.)

You’ll also need:

A 3/8″-16 “Bottoming”, AKA “Blind,” tap and it’s matching drill bit. Good taps nearly always have the required drill size engraved on them. (Unlike a regular tap, a bottoming/blind tap will cut threads all the way to the bottom of a hole that is closed or doesn’t have enough clearance behind it.)
A smaller bit, like 1/8 inch, used to drill starter holes may also be helpful.
Some 3/8″­16 threaded rod and a matching nut. (A bolt with long enough threaded length and matching nut will also work.) Consider a Grade 8 hardened rod/bolt for this. (Class 10.9 if your using Metric stuff.)
A 1mm (.040 inch) drill bit.
A dial gauge with suitable mount.

The process

NOTE: The hole in the cam MUST NOT exceed 1/2 inch deep! That holes dimensions are very important and were determined by GM to leave the cam strong enough to accept the new gear and not break later. Use depth stops or at least tape on the drill bits to prevent going too deep. The hole in the cam may be easier if you first drill a smaller pilot hole.
Drill and tap all three holes before removing the cam gear. This will help keep trash away from the cam bearings. Be careful drilling thru the gear. Slide some sheet metal behind the gear to protect anything you may hit with the drill.
Rotate the gear so you aren’t drilling over the cam thrust plate!
Take your time tapping the holes. It may be easier to use a standard tap to start the hole and follow it with the blind tap to finish. A regular tap definitely won’t give enough thread in the cam hole.

Stuff rags into the oil pan to collect
waste from drilling and tapping. (A single large rag is best.)
Use the scribe lines to drill and tap two holes in the cam gear. Get them in close to the gear’s hub. The phenolic is strong but you want as much grip as possible for the draw bolts. (Make sure you don’t get so close the drill or tap will hit the cam!) This may be easier if you drill pilot holes first with a small bit. If you hit the metal hub, that’s ok. It’ll just give more strength to pull against.
Drill and tap a hole in the center of the cam.

Install the puller. Cover the hole in the cam to protect the threads! (If you can’t use the screw pad that comes with the puller then use washers or coins.)
Slowly pull off the gear.

While the gear is off…

(This is from the same TSB with the gear replacement instructions.)
GM recommends that a 1mm (.040 inch) hole be drilled in an oil gallery plug to
improve gear oiling. I DO NOT know exactly where this gallery plug is! The hole can be smaller but must not be bigger than specified! (Later versions of L4 may already have this hole.)

Install the new gear

Use some large washers with the threaded rod and nut to press on the new gear AFTER installing the crank gear. Oil the threads before you press the gear.
Make sure the timing marks are lined up!
Set up the dial gauge so it touches the end of the cam. Per the GM TSB, the cam should have .0015 to .0050 (inch) of end play with the gear installed.
Make sure all the rags are removed from the oil pan and install the timing cover, balancer, etc.

PFKB Method

PFKB has a tool set you can purchase for replacing the cam gears. This is another variation on the GM method. I don’t know anything more about their kit than what is on their web site.

Yet another Method

This one is just a theory. As long as you’re very careful there’s no reason it can’t be done like this. There are loads of variations possible here. This is the one idea I was playing with recently.
It should also be possible to “crack” the cam hub for removal. This could give you a way out if no pullers are available. Someone mentioned grinding in a forum thread… I would not do that. Grinding or power saws would likely throw stuff everywhere.
To install the new gear you will still need the hole in the cam, etc. (As described above.)
To do this use a fine drill bit to drill a series of holes in the hub. Drill the holes so they are about 1/8 to 3/16 inch from each other. Exact distance will vary some depending on which bits you choose to use. (Fine bits are easier to control.)

WARNING! Make sure you do not drill over/into the thrust plate! Use a depth stop to make sure the drill can’t hit any thing behind the gear. Use a piece of sheet metal to shield the area behind the gear. Adjust the stop as needed to prevent drill contact with the cam, bearing or block! You’ve got to be very careful drilling the holes near the cam!

It seams like allot of holes at first but you save a bunch by making use of the access holes cast into the cam. (The holes let you get at the thrust plate bolts during cam removal.) The gear itself is fairly soft so drilling those holes should go pretty fast.
Drill the first hole close to the cam and the rest straight out from it. The holes don’t have to be perfectly straight. Make sure you don’t hit the cam with the drill. (You may need 2 rows of holes like this.) Once the little holes are done, use a larger bit to connect as many of the small holes as possible.

The fiber is actually covering part of the metal core. You’ll need to make the line of holes reach at least to one of the access holes molded in the gear. You may have to go all the way to one side of the gear.
Once you’ve made a line of holes and enlarged then as indicated, use sheet metal screws/bolts to spread the crack. Work from the outside of the gear toward the core. (You want pointed screws not tapping or drill tip screws.)

In car cam removal

By dropping the rear of the cradle, it is possible to remove the cam without pulling the motor. A number of people have done the gear change that way.
There are several accounts of this in the forums. Be extremely careful that you don’t damage a cam bearing when extracting or inserting the cam.
In car cam removal is pretty tricky. I’d strongly recommend you try one of the other methods. Disturbing a used cam can have unpredictable results on high mileage motors. Make sure all lifters and pushrods are returned to their original locations. Put nylon wire ties on the pushrods before you remove them so you know which end goes up later. Buy or make a tray to keep everything in order.
You may need to remove the alternator and/or intake manifold to get enough room to work on the lifters. The rest of the procedure is essentially the same as published in Haynes etc.
There is an advantage to cam removal… It allows full inspection of the cam and lifters. This would be more important to flat tappet setups than rollers. It’s not at all uncommon for flat tappets to wear cam lobes completely flat.

Other Info

Third party damper sources for 87+ VIN R, replaces 10101369.

Even though Damper Dudes is new, they also rebuild them so they want the old ones. That could be a problem since many people only have a steel pulley, not a damper. Parts America does provide a picture so you can see what the new damper looks like.
Autozone only sells new dampers. I’d recommend new because you also know the pulley is fresh. A worn pulley won’t help belt life… Serpents can be a big enough pain without adding an iffy pulley.

by Ray Paulk

The gas gauge on a Fiero seems to be a PITA (Pain in the Butt) for all of us. I ran out of gas 5 times before I broke down and decided to fix it. It didn’t take too much investigation to figure out that the problem is with the sending unit which is part of the fuel pump assembly inside the tank. Having dropped Fiero gas tanks before I was none to anxious to jump into this job. But when my fuel pump failed and I was forced to drop the tank, I figured that I might as well fix the sending unit too.

The fuel gauge sending unit for the fuel gauge is a simple potentiometer which varies its resistance with the level of the fuel in the tank. It’s supposed to read 0 ohms when Empty and 90 ohms when Full. The problem is that this “pot” never seems to get down to 0 ohms and always goes much higher than 90 ohms. Of the fuel gauge sending units that I’ve have removed, they usually read about 15 to 20 ohms with the float all the way down (Empty) and about 120 ohms with the float at the top. This means you’ll run for quite a while with the gauge reading Full and run out of gas when the gauge reads 1/8 to 1/4 tank. Sound familiar?

A potentiometer is a variable resistor. Its comprised of a resistance coil and a “center-tap” or “wiper” which slides along the coil. The resistance is measured between the center tap or wiper and one end of the coil. As the wiper moves along the coil, the resistance between the wiper and the end of the coil changes. Right at the end, under ideal conditions, it reads zero.

The potentiometer of the fuel gauge sending unit is made from components. The resistance coil is literally a 1/16″ fiber board about 1/2″ wide with a resistance wire wrapped around it. The “wiper” of the pot is tied to the tank float. As the fuel level rises and falls, the wiper moves along the edge of the coil and varies the resistance between the wiper and the top end of the coil. (The float goes down and the wiper goes up.) There are fine tune adjustment screws which actually tilt the coil board in and out to change the contact point of the wiper but its not enough to really fix it.

The problem is that the wiper never gets down to the bottom coils of the resistor to read zero. The fix is to “short” the bottom coils to meet the point where the wiper contacts at its bottom most position. Here’s what to do:

Remove the sending unit from the tank. (Not a really fun job but necessary.) The wiper mechanism and resistor board should be fairly obvious they are probably under an aluminum cover which is easily removed with bend tabs. Note the screws with the springs on them at the top and bottom of the board. These are the adjustment screws. Note that the last coil of wire falls under the spring on the screw. This is the contact point.

Although you can bend things to try to make it work, this might damage parts and is often ineffective. You may break something. Another “not recommended” technique is to remove some coils at the bottom. Here too you can get in trouble by breaking the wire or loosening the coils. Also, to get to zero ohms, the wiper would have to slide to the last coil and perhaps off the coils all together. Not a real good solution.

The better way is to first set the adjustment screws to a neutral position 1/2 way through their adjustment. Now mark the lowest point the wiper goes on the coil (mark with something like a “Sharpie” pen.)

On the side of the board, you will have to clean the surface of the coils because you are going to make a solder bridge from the last coil to the coil where the wiper last contacted. I either use a wire wheel in my Dremel tool or a fiberglass burnishing brush which I got at Radio Shack (Cat. No. 64-1986). When you have the varnish removed from the coils and they are clean, coat them with solder flux (plumbers paste) even if you use resin core solder. This wire does not like solder. I even use Muriatic acid to help clean the wire. Then solder all the last coils together. Note, this is electronics work, not work for solder guns or torches. If you don’t have a “pencil” type, electronics duty soldering iron, you may be better off going to an electronics store or TV repair place to have this done.

Now remount the coil board. Naturally clean the springs and screws for better contact. (0 ohms is tough to get … when you want it). Attach ohmmeter to the gauge out put terminals (they should be pink and black, at least in the wiring harness. If not, they should be obvious if you’ve gone this far.) Hold the float as low as it can go and run the upper adjustment (empty position) screw in and out to see what the lowest ohm reading you can get it. On mine I got 1.9 ohms. I turned the adjustment screw in on my units until I got a consistent low reading of 1.9 ohms. I then backed it out ’til the ohms started to climb. You want to set this adjustment right at this break point.
Now do the same with the lower screw ’til you get 90 ohms with the float all the way up. When you get this “Full” output set, go back and recheck the Empty set point. You’ll probably have to do this a few times as one setting affects the other. Remember that the bottom must be set right at the break point mentioned earlier. When you get both ends set, your sending unit is calibrated.

Now you can pop the cover back on the resistor coil, drop the sending unit/fuel pump back into the tank and “throw the tank back up in place. (Ya, I wish it were that easy. I always tend to cut the heck out of my hands when I do this. It’s trying to get all those damn tubes and hoses back on that’s a killer.)

If you did the job right, your gauge will be correct. If you still have problems, you can check the gauge with a 90-ohm resistor and a solid wire. Remembering that the pink and black wires are the sending unit wires, you can put a 90-ohm resistor in place of the sending unit. The gauge should read Full. Then put a solid jumper in and the gauge should read Empty. If it doesn’t, your gauge is messed up. But a bad gauge is seldom the problem.

After several attempts to complete he window express down mod as listed in the newsletter and not being able to get it to work, I decided to find out what was going on. I found that the Ford uses a power window switch that grounds both window wires when it is in the off position while the Fiero leaves these wires open. After some head scratching I figured out how to make everything work using two 5 prong relays I bought at Bumper to Bumper Auto for 5 bucks each. I have added a diagram to show the new wiring for the express module and the relays.

• Notice that the wire from the window motor up terminal (Brown) and from terminal 4 (yellow wire) on the express relay go to the normally closed terminal on relay one.
• The wire from the window motor down terminal (Blue) goes to on the express relay terminal 1 (red wire)
• Express relay terminal 5 (black wire) goes to the normally closed terminal on relay two
• The wires from the switch up (Brown) go to the normally open and to one of the coil terminals on relay one
• The wires from the switch down (Blue) go to the normally open and to one of the coil terminals on relay two
• The common terminal goes to ground and to the other coil terminal on both relays one and two.
• The wire from terminal 3 on the express relay goes to power with key on

Fiero power window express down mod

A little information about the module used for this mod:

To the best of my knowledge and experience in the junkyard, these modules were only used in generation 2
Taurus/Sable and Explorer vehicles. They can be found inside the driver door skin, mounted underneath the armrest support. The Ford part number for the module is: F2DB-14B118-AB. I have heard that the dealer price for these modules is around $50, but if you grab a handful of them and tell the junkyard guy that they’re just window relays, you’ll get better treatment. If you’re cutting it out of a junkyard car, of course you want to get as much of the harness wiring as possible.

And now for the installation information:

There are five wires coming off of the express down module. They are as follows:

1. Motor side of down wire (red)
2. Switch side of down wire (white/black)
3. - +12V (blue/black)
4. Up wire (yellow)
5. Ground (black)

If you remove the module from the harness connector, you will be able to see the numbers stamped into the plastic.

For the switch to which you want to connect the module, use a meter or test light to identify:

• Keyed +12V wire
• Ground wire
• The wire that goes to +12V when you press up
• The wire that goes to +12V when you press down

Here are the connections that must now be made:

Use an inline spice to connect module #3 to the keyed +12V source.
Use an inline splice to connect module #4 to the up wire
Use an inline splice to connect module #5 to the ground

Cut the down wire, leaving you enough room to butt splice each end. Connect module #1 to the electric motor side of this wire. Connect module #2 to the switch side of this wire.

At this point, all of the electrical connections have been made. All that is left to you is to reassemble everything and fasten the module so that it doesn’t rattle.

SEE “Fiero Power Window Express Down Mod Correction. ***” BEFORE STARTING

A little information about the module used for this mod:

To the best of my knowledge and experience in the junkyard, these modules were only used in generation 2 Taurus/Sable and Explorer vehicles. They can be found inside the driver door skin, mounted underneath the armrest support. The Ford part number for the module is: F2DB-14B118-AB. I have heard that the dealer price for these modules is around $50, but if you grab a handful of them and tell the junkyard guy that they’re just window relays, you’ll get better treatment. If you’re cutting it out of a junkyard car, of course you want to get as much of the harness wiring as possible.
And now for the installation information:

There are five wires coming off of the express down module. They are as follows:

1. Motor side of down wire (red)
2. Switch side of down wire (white/black)
3. - +12V (blue/black)
4. Up wire (yellow)
5. Ground (black)

If you remove the module from the harness connector, you will be able to see the numbers stamped into the plastic.

For the switch to which you want to connect the module, use a meter or test light to identify:

• Keyed +12V wire
• Ground wire
• The wire that goes to +12V when you press up
• The wire that goes to +12V when you press down

Here are the connections that must now be made:

Use an inline spice to connect module #3 to the keyed +12V source.

Use an inline splice to connect module #4 to the up wire.

Use an inline splice to connect module #5 to the ground.

Cut the down wire, leaving you enough room to butt splice each end. Connect module #1 to the electric motor side of this wire. Connect module #2 to the switch side of this wire.

At this point, all of the electrical connections have been made. All that is left to you is to reassemble everything and fasten the module so that it doesn’t rattle.