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

109,915

Possibly faulty throttle position sensor.

1 out of 1 people think this is helpful.
109,915

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

#1 Andrew Welsh
Andrew Welsh
Reputation 230
#2 THORNY68
THORNY68
Reputation 220
#2 Steve Neyens
Steve Neyens
Reputation 220
View All

Related Models For Sale

Used Pontiac Firebird
10 Great Deals out of 732 listings starting at $3,875
Used Chevrolet Corvette
118 Great Deals out of 20,553 listings starting at $3,000
Used Ford Mustang
458 Great Deals out of 45,660 listings starting at $1,999
Used Chevrolet Camaro
214 Great Deals out of 30,774 listings starting at $1,217
Used Mazda RX-7
63 listings
Used Toyota MR2
20 listings
Used Nissan 300ZX
132 listings starting at $3,995
Used Dodge Charger
403 Great Deals out of 28,083 listings starting at $1,988
Used BMW 3 Series
981 Great Deals out of 31,783 listings starting at $1,000

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.