Hey Rynoblaster! Has it always done that? This could explain part of it.
When the engine coolant temperature is approximately 158 F or below, the ignition timing map in the ECU (Engine Control Unit) is changed to retard the engine timing. This timing change is done in order to quickly heat up the exhaust catalyst to reduce emission gases. This change causes part of the combustion process to occur as the exhaust valves are opening in the cylinder head.
Wednesday, February 24th, 2010 AT 9:01 AM