Issue with stuck idle when hot (Page 1/1)
jjd2296 JUN 20, 09:33 AM
So im trying to sort out a small issue i exerience when the car is nice and hot after a drive. The idle will hold at either 2k or 1500 while driving. If i tap on the peddle it settles back to 950. if I come to a stop it will sometimes drop to 500 then back to 950, sometimes needing a slight tap on the peddle.

Then if I turn it off and go to start it it takes a bit on the crank before it goes. and my idle issue is back. Non of this happens on a cold start or on a short drive with engine not hot.


its not my throttle sticking as ive tested that. Ive replaced ther IAC twice as well. could it be carbon build up in the TB?

its the weirdest thing.
cebix JUN 20, 12:07 PM
Engine, year, transmission?

I'd still say your throttle cable might be stuck. Impossible to tell if you're on your own as I have a similar problem and moving the throttle by hand all is great.

But if the cable sticks you have to have another person behind the wheel hitting the gas while you look at your throttle.

[This message has been edited by cebix (edited 06-20-2021).]

phonedawgz JUN 20, 12:35 PM
A hard short hot stop can be caused by a leaking fuel injector. Look for dribbles on the 2.5. Check for falling fuel pressure on the 2.8.


FYI - The ECM is programmed to idle the engine substantially faster when the car is rolling than when it is stopped. With the car traveling at 25 mph take the transmission out of gear and slowly come to a stop. At about 6 mph the idle speed will drop.
jjd2296 JUN 20, 01:17 PM
sorry i should have been more specific. I have a 3.4 pr fully modded with darrel morse TB and supercharger. theres no injector leak, like i said it only stick when hot, like after a hour or more drive. the throttle canle is super loose no binding at all. i didnt have th eissue prior to installing the darrel morse bore TB, im thinking that maybe when it gets hot that the spring is sticking on the tb?

[This message has been edited by jjd2296 (edited 06-20-2021).]

Skybax JUN 20, 09:29 PM

quote
Originally posted by jjd2296:

i didnt have th eissue prior to installing the darrel morse bore TB, im thinking that maybe when it gets hot that the spring is sticking on the tb?




Start there, swap out and see if it goes away, probably heat expansion related issue to that component.
jjd2296 JUN 28, 03:35 PM
thnx Skybax, I swapped out the TB for a known good one. problem gone. Ill have to take this one apart and sand down some of the parts for better movement.