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Topic: Engine Revving on its own (Read 883 times) previous topic - next topic

Engine Revving on its own

Okay, so this has been killing me lately...  I'll be driving my 86 5.0 Cougar, and I'll get to a stop sign or a stop light, and it will start revving up on it's own.  I'm talking at least 2000rpm or more.  But it's not just when I idle.  I pulled away from a stop sign and just let the engine go by itself, didn't even hit the pedal, and I reached 45 before i had to hit the brakes and slow myself down.  Usually I have to hold the brake and the engine is pulling against them, so I know it's jacking up my break pads as well.  I thought it might be the idle air control valve, but I replaced that, and it didn't help.  it's been going on for about a year now, but only recently has it gotten so bad that i can just let my car drive itself...  any help/ideas?

Engine Revving on its own

Reply #1 –
Other than a vacuum leak, I'd suspect a bad/mis-adjusted TPS...

Engine Revving on its own

Reply #2 –
i've read a lot of posts about TPS's, and I'm embarrassed to say I don't know what that is...  and how do i know if that is the problem?

I've checked the Vacuum tubes and such, and i haven't found a leak or anything there.  i finally got it to rev up today with the hood open.  it seemed like everytime it would start doing so and i would pop the hood, it would stop and i wouldn't be able to watch it do so.  But today it finally did, and it sounds like the intake is opening up on it's own and reving up.  i'm not sure if that is the problem, or just a response to the problem form the engine...

Engine Revving on its own

Reply #3 –
So I did some research, figured out what a TPS is, and read through this forum and others to address the problem.  I then replaced the TPS ($30 at Autozone, $50 at O'Reilly's) and it looks like my problem is finally solved.  I ran it for nearly an hour and the problem didn't come back at all.  We shall see over the next few weeks, but for the moment is seems like we're good.  Thanks for the help!