[BBeer]

I need some help. My car idles fine until I reach operating temperature ~200 F. Then the idle increases to around 2000 rpm and fluctuates. The problem began as an all around lousy idle. So far I have: replaced plug wires, o2 sensor, and vacuum lines and cleaned the ISV. What exactly changes when the engine reaches operating temperature? I think if I had a good understanding of this I could locate the problem (without the VAG 1551).
Thanks,
Brian
92 SLC

 

[jumungi5]

Re: Warm Idle Trouble (BBeer)

You say at about 200F the idle speed rises to 2000rpm, gradually or quick? Check connections at the coolant temp sensor, located on the thermo housing. The ECU may be getting a false signal that the coolant is still cold and therefore is adding fuel, and/or closing the ISV to raise the engine speed.
At operating temp the ECU goes into 'closed loop' mode thereby using the o2 & temp sensors to regulate fuel and timing.

 

[asylum]

Re: Warm Idle Trouble (BBeer)

This is the exact problem Im having with my car. Ive tried everything I can think of but nothing solves the problem so I decided to go with a stand alone engine management system. That should solve it and it'll give me the capabilities of running higher boost!