Hi folks
Car seems good overall, but at start up & idle today it was sometimes uneven, thought it was about to stall, but came back to being ok, yet seemed a bit rough sometimes.
The last time this all occurred, it was stalling completely, and i got codes for the Upper O2 sensors
& i replaced them.

this time, really its only occurred today only , the stalling is much much less, I thought maybe the lower O2 sensors initially were the culprit, but i have no OBD2 error codes indicating anything is at fauit.

MAF sensor replace 3 years ago, cleaned a few months ago
Upper O2 sensors replaced, Bosch replacement.... but lowers not replaced yet
New fuel filter, fuel pressure regulator cleaned
Air trunking is New OEM a few years ago

Question is....apart from looking for air leaks (air trunking ie pretty new though), do i wait for
an OBD2 code to come for the possible Lower O2 sensor or just replace them? Or is their something else to consider
I dont want to be stranded with the car, would like to find the problem

Peter

 

Check fuel trims.

 

NOT an X308 person.

BUT

On the AJ16, and earlier V12 (Fossil Technology by comparison), the CTS, Coolant Temp Sensor going flaky returned similar results. NO codes, the cars never had a reader, too old, just suggesting, based on what you have done so far.

 

Is “air trunking” the air intake tube??

Does the engine run rough primarily when first started up vs warmed up?