I'd like to understand better the reasons that a PCM / ECU would decide to retard timing at idle.
I'm aware of the following:
knock noise similar to knocking picked up by the sensor a defective knock sensor engine overheating missing knock sensor on some cars ( some Hondas I think )
are all possible reasons; are there any other reasons why the PCM would retard timing at idle?
Would a code always be set when the timing is retarded?
My intention in this question is retarding beyond what is normal, due to some kind of fault condition or out of spec operation.