Idle Troubles
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Joined: Aug 2003
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Idle Troubles
I have a 1991 Ford F-150 4x4 with a 302. For some reason my truck idles at 3000 RPM's and I cannot figure out why. I have checked for vacuum leaks and found none. No codes pull telling me that any sensors are bad. When I unplug the electrical connection on the IAC it idles down to below normal and runs rough. I have tried installing a new IAC with no luck and have cleaned the old one with no luck either. Then when I unplug the electrical connection to the MAP sensor it does the same thing, it idles down to regular but will fluctuate up and down and then the check engine light comes on because no MAP sensor is plugged in. Any help would be appreciated.
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Joined: Jan 2003
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From: Still under the hood in O
Idle Troubles
When you unplug the MAP it should die. What happens when you unplug the vacuum to the MAP?
Did you look for a vacuum leak with starting fluid around the upper intake mounting flanges? (also spray into the cavity in the middle where the Torx bolt is)
Did you look for a vacuum leak with starting fluid around the upper intake mounting flanges? (also spray into the cavity in the middle where the Torx bolt is)
Senior User
Joined: Aug 2003
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From: kansas
Idle Troubles
Check the voltage at the green wire from the tps( throttle position sensor). If its too high the ecm thinks your at part throttle and will hold the iac further open than it should. Voltage should be about 1 volt or less I think.
Senior User
Joined: Aug 2003
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Idle Troubles
i had a wire from the tps rest on the motor and get hot n melt, it drove me nuts becaust it was so intermittent, i had a different problem but am just saying it wouldn't hurt to check the wiring harness over quick to make sure a wire didnt fry.
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Joined: May 2002
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From: Virginia
Idle Troubles
I had this problem also. I tested the TPS and it was reading too low. I ended up replacing it with a new one and set it at .98 volt.
That took care of the problem for me.
Now I just gotta figure out why it's pinging so much still...
That took care of the problem for me.
Now I just gotta figure out why it's pinging so much still...
