Posted by: JSO2003P71
2001 high idle - 10/09/21 08:29 PM
I have a 2001 that is giving me a fit with the idle once the engine warms to its peak running temp. It runs great and idles around 800 rpm until it gets completely warmed up. Once it is warm it wants to idle at around 2200 rpm in neutral and park. I replaced the IAC with a new motorcraft one from Ford. Have replaced all the vacuum lines and sprayed carb cleaner all around the intake and throttle body and vacuum lines with no increase in idle. I cleaned the MAF sensor and cleaned the throttle body also. No leaks in the air tube to throttle body. Throttle return spring is tight and returns throttle to closed position. When it goes to high idle (2200 rpm) it stays steady there and does not lower. However if I turn the engine off and immediately restart it it will idle normal again. There is no check engine light or engine codes. Anyone know what the problem could be? Its driving me crazy. If I leave the car in gear it still idles high but not at 2200 rpm.
Posted by: JSO2003P71
Re: 2001 high idle - 10/10/21 09:43 AM
I know, its a tough one. I am wondering if it is a problem with the ecm since turning the car off and restarting it make it run normal for awhile.
Posted by: Hound
Re: 2001 high idle - 10/10/21 12:50 PM
Did this just start happening out of the blue or did it start after you did some other work?
Could it be the IAC?
Posted by: JSO2003P71
Re: 2001 high idle - 10/10/21 01:54 PM
It just started doing it one day. The IAC is new. I bought it from the Ford dealership. Thinking back on it I think it did start about the same time I replaced the fuel pump. Could that have something to do with it? It was a aftermarket fuel pump.
Posted by: ColescottFTW
Re: 2001 high idle - 10/10/21 02:50 PM
Did you replace the gasket for the IAC?
Just had this issue, and it was the stupid gasket. Visually looked good, but was bad.
Posted by: Hound
Re: 2001 high idle - 10/10/21 03:37 PM
More likely this has to do with a sensor than a mechanical part. I don't see how a pump could change your idle speed.
Gasket as Colescott suggests may be a good start. Do you still have the old valve? I would swap them and see if there is a difference. Motorcraft is just contracting this electrical stuff out anyway. Certainly try a new gasket or some sealer.
Posted by: TheShadow
Re: 2001 high idle - 10/10/21 07:14 PM
There might be an issue with the throttle plate not sealing completely, intermittently.
Posted by: JSO2003P71
Re: 2001 high idle - 10/10/21 10:33 PM
I am not sure if I changed the gasket or not. If it came with a new one I changed it. I will get a new gasket tomorrow from orielly. The problem started almost a year ago and the IAC was the first thing I changed. I took the car for a ride today with my scanner hooked up so I could check fuel pressure once the car started the high idle. Fuel pressure stayed at 39-40 lbs. Just like always as soon as the temp got half way it started idling at 2200. I was driving down the road with my foot off the accelerator doing a steady 45 mph. I wish I knew more about the what the numbers should be on the OBD2 live data. I do still have the old IAC in the trunk
Posted by: JSO2003P71
Re: 2001 high idle - 10/10/21 10:37 PM
Could a bad TPS cause this? Its strange how it only happens when the engine reaches a certain temp. When it happened today once I got home I turn the engine off and restarted it and it stayed at high idle (2200).
Posted by: YoungP71dude
Re: 2001 high idle - 10/10/21 11:46 PM
As TheShadow suggested, if the throttle plate isn't sealing, check your Throttle Position Sensor. Chances are it could be busted and it's trying to compensate based off the other intake/exhaust sensors. If your shifting is at all erratic or harsh, those are more symptoms of a bad TPS. You can check this more easily with live data from an OBD2 tool (via absolute throttle position) or a good ol' fashioned multimeter.
Should your TPS be bad, it's easier to replace the entire throttle body assembly as those TPS screws are an absolute pain to remove gracefully and properly without a welder or impact screwdriver.
Posted by: Hound
Re: 2001 high idle - 10/11/21 04:47 AM
The test on my 2004 is just two little screws. Had no issues with mine when I took it off while switching throttle bodies.
Posted by: JSO2003P71
Re: 2001 high idle - 10/14/21 04:00 PM
I got a complete throttle body with TPS sensor and IAC from the junkyard. Cleaned it up to look like its new. Was going to swap it today but got stuck at the doctors all day.
Posted by: JSO2003P71
Re: 2001 high idle - 10/17/21 02:00 PM
After swapping out a complete throttle body assembly with a used one I got for $27. at the junkyard the car is fixed. It runs fantastic now. Thanks to all those who responded for your help.