In and out of open loop at idle

[LBSBLOWN]

My 2008 Yukon Denali 6.2L will go into open loop at idle and the comanded AFR will go to 16.0 for a few seconds then jump to 11.0 for a few seconds then jump back to closed loop and durring all this open loop crap the idle is rough but smoths out as soon as it goes back to closed loop.

It will continue to do this as long as your at idle, it goes OL lean then rich then CL and then starts over again.

Any idea's on what to look for? BTW it does this with the stock tune.

[LBSBLOWN]

Mine is doing exactly like the one in this thread but will do it evan when the engine is warm.
(http://www.hptuners.com/forum/showth...ght=rough+idle)

[LazMan]

Its a catalytic converter test. Normal behavior. You can disable it in the Engine Diagnostics (memory dont fail me now!) section. Raise the min temperature to 300F and max temp to 310F (for example) and voila...or look for the codes if you're more daring and un-check the tests.

I prefer changing the temps to prevent "side effects" from popping up.

[LBSBLOWN]

Its a catalytic converter test. Normal behavior. You can disable it in the Engine Diagnostics (memory dont fail me now!) section. Raise the min temperature to 300F and max temp to 310F (for example) and voila...or look for the codes if you're more daring and un-check the tests.

I prefer changing the temps to prevent "side effects" from popping up.

Thanks LazMan I will give it a try tonight, I only see a Cat test dissable/enable and a post O2 test dissable/enable.

[Bill@HPTuners]

Thanks LazMan I will give it a try tonight, I only see a Cat test dissable/enable and a post O2 test dissable/enable.

Yes.