Question about 1986 Pontiac Fiero

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My 86 Fiero GT only has 58,000 miles, it has been in a climate controlled storage building most of its life, so, it has sat, it had a new fuel pump and strainer basket, and filter installed and old gas drained in September. It idles fine, but when you go to accelerate, it tries to die, I have changed the air filter, and cleaned all the buildup off the throttle body? Could it be some sort of egr, mass airflow, tps or other sensor? I have sea foam mixed in the gas now to try to clean the injectors, any help would be appreciated.

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  • Anonymous Jan 02, 2011

    It has no warning or check engine lights on in the dash.



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A wideband oxygen sensor would sure help tell you if the problem is too much, or two little fuel.
My V6 Fiero did this a couple of times for different reasons.
The first time was because all of my spark plug wires, coil wire, dizzy cap & rotor had all sorts of corrosion and at night you could pop the trunk and see sparks jumping all over and it wouldn't rev up past 2500 RPM. A quality tune-up fixed that problem.
The second time it turned out that my catalytic converter was partially clogged and wasn't allowing the exhaust gas out of the engine. It was basically suffocating above 2200 RPM. I unbolted the exhaust pipe where the crossover Y-pipe connected to the converter and drove around the block with a loud exhaust leak. The power was back, and I had found the culprit.
If neither of these apply, check your ground wires. If you are concerned with testing sensors:

Throttle Position Sensor on Throttle Body normally reads from +.5-4.5V as you open the throttle with car ON, engine stopped.

Manifold Air Pressure Sensor on pass. side of intake plenum. With key ON engine stopped it should read +4-4.5V depending on altitude.

Coolant Temp Sensor is in lower intake manifold near thermostat housing. 2-wire connector. Check resistance decreases as temperature increases. Should not be infinite or 0 Ohms ever.

Intake Air Temp Sensor doesn't have much control over fueling, but it is almost the exact same sensor as the Coolant Temp only it is located in the metal air cleaner housing. Again, resistance will decrease as temperature increases, and no infinite or 0 Ohm readings.

Really the TPS and the MAP are the major contributors with Fiero V6 speed density style Fuel Injection, and the Temp sensors while still important, don't have as much dependency placed upon them.

Posted on Aug 11, 2014


I would drain and replace the gas, old gas will cause this sort of problem.

If you have already changed the gas, first you need to check the fuel pressure, there is a location the fuel rail to attach a gauge (looks like a a/c refill fitting)

If you have good gas pressure, you likely have 1 or more clogged injectors, you can try and clean them, or simply swap them out.

A good source for parts is fierostore .com

Hope this helps.

Posted on Feb 18, 2011


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