Acerbus 2.0

...give your car at least 5 minutes to warm up at cold start. I was getting these codes in my car every 2 - 3 days, even after checking the O² sensors, and revising the tune files. They were fine.

I noticed I was getting these codes the mornings when the alarm clock didn't wake me up on time, and I just got on the car and left hastily. I started letting the car warm up 3 - 5 minutes each morning and those trouble codes haven't returned in a month of (daily) driving. Same tuning.

Just a heads up.

dominant1

weird, they shouldn't show up at all under any circumstances....

Tylus

Thank you for this. My car has been doing this lately. I'v been leaving 1 hour earlier for work.

Gonna try it out and hopefully doesn't come back. Already had Brenspeed revise it once with no luck

SpartaPerformance

O2 defoulers are the answer. I use them, never had a CEL warm up my car normal interval.

Tylus

found a fix for the problem on another forum. it has to do with the self-test timer for the PCM and O2 sensors. the fix seems to be retarding the test timing a tiny bit. this gives the O2 more time to warm up prior to be tested.

the theory is that moving the front O2's from their OEM location to about 1.5 feet farther downstream causes the O2 to heat up later...but the PCM is still looking for the self-test at the same time. So the O2 "fails" and the PCM never goes closed loop. Makes the car A/F go pig rich and then CEL's and poor driveability.

SpartaPerformance

That theory is 100% correct.

Blacksmoke

BTW... also...
EVERY long tube job on these cars should come with a tune that turns off the rear 02 sensors. PERIOD.
If not you will eventually get cat inefficiency codes thrown at you.