Engine High idle

Discussion in 'SN95 4.6L Mustang Tech' started by docambriz, Mar 19, 2013.

  1. What up I'm having a problem with my 2000 mustang GT.
    I just got back from overseas and my car was sitting for about 8 years it was started every once and a while but was not took care of like it should have been. I have been getting it back together and I can't seem to get rid of this high hanging idle (1050-1200). While driving I let the gas pedal go its stays at 2000 (4sec) them drops to 1500(3sec)then to the high idle.
    I have check for vacuum leaks
    Cleaned the MAF sensor
    Cleaned the plenum
    Cleaned the throttle body
    Cleaned the EGR valve
    Replaced the EGR vacuum solenoid
    Replaced the air filter
    Replaced IAC
    If you can think of anything that would be great and thanks you ahead of time.
  2. run codes and follow the surging idle checklist. It WILL fix your problem if you follow it properly :)
  3. The PCM controls idle speed using a closed-loop controller. Part of this control involves learning many parameters and storing the values in memory. This process takes time and even varied driving conditions for the PCM to establish what is idle, how the engine responds to various PWM inputs to the IAC, what accessory loads do to it and so on.

    In short, have you given the PCM a long enough time to re-learn the idle?
  4. Along with trinity and madspeed, I would add that you might wanna check everything throttle related. Try revving the engine from the TB and watch to see what happens. Your throttle blade might have gunk in there, the throttle return spring might be loose, the throttle coil on the outside of the TB may be loose. Also check the throttle link cable...it may be getting stuck somewhere between the pedal and the TB.
  5. Thank you all so much just fixed it today had a death to deal with first. Just wanted to let you guys know that it was idle relearning procedure that fixed it.