HELP...i got a 99 GT my engine revs up after i drive it home from work!!

[oonico]

please can anybody give me some pointers on what i need to buy or replace to stopp the reving up on the rpms on my car...after i drive for about 45 home after work and i stop at a light, my car acts like a press on the gas when my daym foot is on the break!!! some one help im no mechanic !!! so any suggestions on this is helpfull!!!! ive already replaced the spark plugs...three were cracked..and the fuel filter was replaced also...so what else can it be???????????????

[mustang2422]

could be your idle air by-pass valve. It has a plunger that controls how much air your car takes in at idle. It could be full of carbon or sticking causeing it to not work right. Its located on the throttle body. When mine went bad my car would idle at around 3500 rpm. Lots of fun in traffic!

[351wStang]

I agree its very possible that your IAC is bad. But it could also be your return spring. In my '90 F-150 5.0 my return spring went bad and would hang sometimes causing the motor to rev up to about 3500 between gears and about 4000 when I push in the clutch.

[oonico]

Originally Posted by 351wStang

I agree its very possible that your IAC is bad. But it could also be your return spring. In my '90 F-150 5.0 my return spring went bad and would hang sometimes causing the motor to rev up to about 3500 between gears and about 4000 when I push in the clutch.

thanks guys for your help!!! Im checking those out todday see if i can fix them!!!

[351wStang]

Originally Posted by oonico

thanks guys for your help!!! Im checking those out todday see if i can fix them!!!

Only way to fix the throttle return spring is to drill a new hole in the TB and hook the spring in there to make it tighter. Unless you want to buy a new TB.