>> But I highly doubt that just any CEL no matter what it's for
>> could cause timing to be pulled... maybe just certain CEL's.

Yeah I seriously doubt that every CEL would cause the ECU to pull timing. But seriously, I've watched my ignition timing change just by removing the rear o2 sensor. It seems to go into a fairly conservative and stable mode... put it back in and it's definetely more aggressive timing and seems to be variable and less controlled..