2001 Gt High Idle When Warm

[01gtsilver]

I have a 2001 mustang gt that is a having a erratic idle only when its warm, I have replaced iac, tps, coil packs, spark plugs, and fuel filter, but nothing has helped. I don't know what to do a this point. Sitting at a redlight it idles at around 800 rpm anf in park it idles almost at 1000 rpm. But when I turn the car off then back on it idles normal until I drive it again.

 

[wmburns]

Based upon your symptoms likely you have an unstable TPS signal. Check out the following post: Note the part about HOW the TPS signal works in a "ratch" function.

Troubleshoot IAC idle problems 1996-2004 | Mustang Forums at StangNet

Note that does NOT necessarily mean that the TPS is bad. How do I know? Because the symptoms change after the motor is turned off. Resetting the motor causes the PCM to re-learn a new ratch value.

What could cause your problem? Some examples include:

• Loose or noisy TPS.
• Loose or binding throttle linkage.
• Throttle body idle stop screw set soooooooo low that the TB linkage is not resting on the stop.
• Possibly the most important!!! Weak or missing throttle linkage return spring. Note there should be two.
• After market throttle body installed without correctly setting the TB idle stop screw.

In sort, the TPS value does not matter. What does matter is that the TPS produces the SAME value EACH time the throttle is closed.

 

[01gtsilver]

Its a new tps and stock TB

 

[wmburns]

Its a new tps and stock TB

I gave you a list of "possibilities" the check. It may be a NEW TPS, but if the the electrical connection is dirty it could create the same result. Just like IF the TPS is loose inside the mounting, this could cause the symptom.

IMO what's most important is for you to have an understanding of HOW the PCM uses the TPS signal to control the idle. This gives the best chance of resolving the problem.