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


Possibly faulty throttle position sensor.

1 out of 1 people think this is helpful.

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.

Your Answer

Add photo

Related Questions

  • Hard Start with High Idle 3 answers

    1984 Fiero SE Automatic. This one is driving me crazy! I has spend about $1,000 in parts and repair time at a local shop. Car always had a bit of a high idle (about 2,000 RPM), but I could live with...

    1984 Pontiac Fiero SE or Indy


    Maintenance & Repair

  • Start/Idle 4 answers

    88 Fiero 4cyl. Sometimes it acts like maybe it is flooded. Wont start. Wait about an hour and it starts but idle bounces between 500-1500 rpm for a minute then smooths out. Has a new IAC and fuel ...

    1988 Pontiac Fiero Base


    Maintenance & Repair

  • No Power below 2k RPM 3 answers

    My 88 Fiero 4 cylinder doesn't seem to have much power till 2000 rpm +-. If you rev it a bit and let up, it drops rpms so low that it almost goes dead and sometimes does. When it doesn't go dead it re...

    1988 Pontiac Fiero Base


    Maintenance & Repair

  • how do i fix engine from running rich and car from bucking ? 2 answers

    jus t rebuilt 1986 4 cyl fiero engine. after reinstalling the engine is running rich and the car bucks as you apply the gas, i also get a oxygen sensor code . have replaced oxygen sensor and still get...

    1986 Pontiac Fiero SE


    Maintenance & Repair

  • Can anyone help with an RPM question 1 answer

    I have noticed over the past year or so that my rpm's in my car will go from 1000 up to 2500 while in idle. It began in the winter, so i assumed it was because of a cold start. Id let my coolant war...

    2007 Pontiac G5 GT


    Maintenance & Repair

Search Pontiac Fiero Questions

Pontiac Fiero Experts

Reputation 200
#1 Steve Neyens
Steve Neyens
Reputation 200
#1 dandyoun
Reputation 200
View All

Related Models For Sale

Used Pontiac Firebird"
9 Great Deals out of 904 listings starting at $2,900
Used Chevrolet Corvette"
434 Great Deals out of 20,224 listings starting at $3,688
Used Chevrolet Camaro"
798 Great Deals out of 38,822 listings starting at $2,650
Used Ford Mustang"
733 Great Deals out of 41,077 listings starting at $900
Used Dodge Charger"
646 Great Deals out of 29,672 listings starting at $2,275
Used Toyota MR2"
15 listings
Used Nissan 300ZX"
165 listings
Used BMW M3"
87 Great Deals out of 1,918 listings starting at $5,495
Used Pontiac Grand Prix"
30 Great Deals out of 4,357 listings starting at $1,995