engine will idle but will not throttle past 2500 rpms

Asked by Nov 02, 2014 at 02:31 PM about the 1987 Pontiac Fiero GT

Question type: Maintenance & Repair

have replaced plugs,wires,distributor and coil.could it be bad injectors?

2 Answers

113,285

Possibly faulty throttle position sensor.

1 of 1 people found this helpful.
113,285

I believe on yours it should have three wires going to it. To test (with key in on position but car not running) one wire should have a constant 5 volts. One wire should be a ground and the other wire is the reference wire to computer. If one has the five volt constant no matter where the throttle is and one has a good ground connections then attach your multi meter positive lead to the last wire and the negative lead to the ground wire. With throttle fully closed you should read about .5volts on this wire. As you open the throttle the voltage should gradually climb to 4.5-5volts at full throttle and drop right back to .5volts when you return it to fully closed. If the voltage is different than stated above or the increase and decrease of the voltage is not smooth and steady then replace the switch. Make sure you set the new one at .5volts when fully closed or it won't work right either.

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