High milage 2001 Denali cold idle

Hopefully, someone out there can point me in the right direction before I get too carried away.

This is a 6.0L Yukon Denali has 309,000km with some minor mods. I bought it with the cats deleted. It also has one of those dumb throttle spacer "tornado" air spinny thingys. Usuallly it runs very well, except... When it is freezing out and the engine is cold. The engine will fire and then really misbehaves until the engine temp comes up a little. Sometimes it stalls after start up. I am tempted to lower the desired airflow a bit. But I suspect there may be a mechanical issue instead. Here is my tune and scan.

Attachment 14113Attachment 14114


I have noticed that the IAT is not really correct, because it was below -10deg C

Does it smell rich? How does throttle body gunk look? Sorry, running to work and no time to look at log. You did the right thing by posting it, that's where your answer will be. Also, those things are known for fuel pump issues.

Fix the physical problems first...

- replace IAT sensor since it is bad,
- check operation of other sensors,
- replace front O2 sensors anyway,
- remove and discard the tornado,
- clean MAF, replace air and fuel filters,
- replace spark plugs and wires,
- replace PCV valve and hoses,
- check for leaks in AIR and EVAP plumbing,
- run cleaning additive thru fuel.

Attachment 14233

IT was the intake gaskets leaking...

Glad you got it sorted and thanks for the update! :cheers:

Quote:

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Originally Posted by Ritch

Attachment 14233

IT was the intake gaskets leaking...

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Ahh shoot I'm 4 days too late. Does it count if my wife heard me call out "intake gasket" after reading your first post and before scrolling to the bottom of the thread??? :sly:


While you're in there checkout your knock sensors

Thanks for the update.