Idle Surge When Engine Is Cold

[Shane2GSX]

I'm getting slight idle surge when my engine is completely cold and I've just started. It has actually died on me a few times when warming up. After it's warm, everything is fine and it doesn't idle surge. My mods are up to date. Any ideas on where to start looking?

 

[Glliw]

I would suspect the FIAV in the throttle body.

 

[kingcobb]

I'm pretty sure your ISC (idle sensor control) is on it's way out. From what i have been told, the ISC is basically a bypass for when the car is cold, is helps keep car idling properly until it warms up, once warmed up, it's not used anymore and the car will run fine. So my guess is your ISC is done, and now ## car isn't idling properly when it's cold. Does it run ok when it's warm?

 

[staticbrainwash]

ISC = Idle Speed Control. Does not effect cold starts. It just keeps a set rpm at IDLE.

FIAV = Fast Idle Air Valve. That is the one with the coolant lines in it and a wax pellet. When the motor is cold the FIAV keeps engine speed higher, when warm the wax pellet melts, calming down the idle and settling it down to where you set it warm.

I say either you have some boost leaks when the motor is cold, or the FIAV is bad, or the BISS is leaking when cold.

 

[hun6over]

It is possible to have boost leaks when an engine is cold and then the leaks go away when the engine is warm?

 

[Shane2GSX]

It runs fine once it's warm. I do have a DSMLink log of it if anyone wants to see.

ISC = Idle Speed Control. Does not effect cold starts. It just keeps a set rpm at IDLE.

FIAV = Fast Idle Air Valve. That is the one with the coolant lines in it and a wax pellet. When the motor is cold the FIAV keeps engine speed higher, when warm the wax pellet melts, calming down the idle and settling it down to where you set it warm.

I say either you have some boost leaks when the motor is cold, or the FIAV is bad, or the BISS is leaking when cold.

Thanks for the info..

It is possible to have boost leaks when an engine is cold and then the leaks go away when the engine is warm?

Yes, I could see that. I never thought about it before but I know:

Heat = Expansion
Cold = Contraction

 

[kingcobb]

ISC = Idle Speed Control. Does not effect cold starts. It just keeps a set rpm at IDLE.

FIAV = Fast Idle Air Valve. That is the one with the coolant lines in it and a wax pellet. When the motor is cold the FIAV keeps engine speed higher, when warm the wax pellet melts, calming down the idle and settling it down to where you set it warm.

I say either you have some boost leaks when the motor is cold, or the FIAV is bad, or the BISS is leaking when cold.

Thanks for correction..sorry bout that

 

[eclipsegsx1736]

Post the DSMlink log. My car used to do that with DSMlink, it doesn't do it anymore though but I've replaced just about everything with the engine recently including the engine itself. The STFT would swing from rich to lean, slowly, going back and forth every 3 seconds or so, with the idle. It went away from warm. Never died though.

 

[freshlane]

http://www.dsm.org/how-tos/tttt/tttt3.html