IAC not the problem?
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Joined: May 2011
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From: MD, USA
IAC not the problem?
Hello all,
I have been having an issue with my truck. Every once in a while it will start revving very high at idle. Up to 2000RPMs in neutral. I notice it when I have press the brake harder to start. It is kinda cool cause it launches from stop just after letting go of the brake pedal.
Now I thought this was caused by the IAC being worn out. So last week I bought and replaced it with a new one from Rock auto. I got the Motorcraft one just to be sure. It seems to idle a little smoother, but today this issue reared it's ugly head again.
Everytime it happens I can stop and restart the engine and it will be right again. But that sucks. I want to know how to fix this. Thanks!
I have been having an issue with my truck. Every once in a while it will start revving very high at idle. Up to 2000RPMs in neutral. I notice it when I have press the brake harder to start. It is kinda cool cause it launches from stop just after letting go of the brake pedal.
Now I thought this was caused by the IAC being worn out. So last week I bought and replaced it with a new one from Rock auto. I got the Motorcraft one just to be sure. It seems to idle a little smoother, but today this issue reared it's ugly head again.
Everytime it happens I can stop and restart the engine and it will be right again. But that sucks. I want to know how to fix this. Thanks!
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Joined: Jul 2008
Posts: 58,557
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From: Long Beach Calimexifornia
Lube your throttle cable at both ends. 1500 rpm initially at cold start up is normal. Even a slight resistance will put you at 2000 rpm
A tap of the accelerator should bring idle down.
I would do error code scans too.
A tap of the accelerator should bring idle down.
I would do error code scans too.
Last edited by ymeski56; Sep 16, 2011 at 02:50 PM.
Thread Starter
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Joined: May 2011
Posts: 636
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From: MD, USA
This never happens when the engine is cool. It only happens after I have driven a while and the engine is warm. I've lubed the end of the cable that pulls the throttle.
When it is happening I can press the gas pedal all I want and it will always go back to high throttle. (2kRPM)
Where should I lube the other end of the cable? I am guessing that is on the top of the gas pedal?
I will pull the codes tonight to see if there is anything in there. Thanks Ymeski
When it is happening I can press the gas pedal all I want and it will always go back to high throttle. (2kRPM)
Where should I lube the other end of the cable? I am guessing that is on the top of the gas pedal?
I will pull the codes tonight to see if there is anything in there. Thanks Ymeski
Senior Member
Joined: Jul 2008
Posts: 58,557
Likes: 1,165
From: Long Beach Calimexifornia
This never happens when the engine is cool. It only happens after I have driven a while and the engine is warm. I've lubed the end of the cable that pulls the throttle.
When it is happening I can press the gas pedal all I want and it will always go back to high throttle. (2kRPM)
Where should I lube the other end of the cable? I am guessing that is on the top of the gas pedal?
I will pull the codes tonight to see if there is anything in there. Thanks Ymeski
When it is happening I can press the gas pedal all I want and it will always go back to high throttle. (2kRPM)
Where should I lube the other end of the cable? I am guessing that is on the top of the gas pedal?
I will pull the codes tonight to see if there is anything in there. Thanks Ymeski
Maybe a TPS code.
Thread Starter
Senior Member
Joined: May 2011
Posts: 636
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From: MD, USA
Yeah I bought a new TPS sensor, but didn't install it. Then I moved to a new house, and now have no idea where it is.
Assuming I can find it, it the TPS hard to install? Will I have to dig into the motor?
Assuming I can find it, it the TPS hard to install? Will I have to dig into the motor?
Senior Member
Joined: Jul 2008
Posts: 58,557
Likes: 1,165
From: Long Beach Calimexifornia
Last edited by ymeski56; Sep 16, 2011 at 04:31 PM.
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From: USA
What kind of multimeter probes do you use? Stretching out the rubber insert with anything bigger than a needle might give you mixed results, if water gets trapped inside, corroding the terminals down the road.
The reason why the TPS starts the reading at 1V is for fault checking, such as the code you received.
The reason why the TPS starts the reading at 1V is for fault checking, such as the code you received.
The signal return must be approx 1V at idle and supposedly turning the TPS counterclockwise during installation will more than likely give you a high idle. My guess is turn it clockwise and see what voltage you're at. The DTC "TPS ouf of self-test range" will remind you either way.
Black=GND
Orange=5V Reference
Green=TPS Signal return
Last edited by bluecar5556; Sep 16, 2011 at 09:22 PM.