Need Help! High idle after pressing gas then slowly calms down. 2004 GT

Desync

New Member
Apr 18, 2019
22
1
3
Alabama
Got myself a 2004 GT as a fun project, car is in great shape and everything seems to be in order. Except one small problem I'm noticing.

After pressing the gas and then letting off the gas it idles a little over 1000RPM for quite a few seconds then calms down to normal idle. Also happens when I stop at a red light, stop sign, ect, it'll be really loud then just casually idle down.
 
  • Sponsors (?)


There must be 10,000 or more threads about a "hanging" idle similar to your description. An idle "hanging" around 1000-1200 RPMs and then dropping to a slow idle (500-600) is normal behavior. The behavior is designed in place for SMOG reasons as well making the hydro boost brakes work correctly.

IMO the issue is to separate "normal" behavior from abnormal. 1000-1200 RPMs is normal. 2000 RPMs are not.

If normal behavior then you could change every part in the engine bay and the behavior will remain as the programming has been built into the PCM.

Troubleshoot IAC idle problems 1996-2004​

 
Last edited:
There must be 10,000 or more threads about a "hanging" idle similar to your description. An idle "hanging" around 1000-1200 RPMs and then dropping to a slow idle (500-600) is normal behavior. The behavior is designed in place for SMOG reasons as well making the hydro boost brakes work correctly.

IMO the issue is to separate "normal" behavior from abnormal. 1000-1200 RPMs is normal. 2000 RPMs are not.

If normal behavior then you could change every part in the engine bay and it would behavior will remain as the programming has been build into the PCM.

Troubleshoot IAC idle problems 1996-2004​

Thanks a lot. That solves my problem then. Dude sold me a perfect 2004 GT with no problems then because he didn't know what he was looking at. makes me feel 100x better now.

Main reason he sold it to me was because you only got about an inch or two of gas pedal before it bottomed out, The throttle cable was wore out, I replaced it today and man oh man the power it has now.