Operation CHARM: Car repair manuals for everyone.

Vacuum Advance Control Solenoid: Description and Operation

Ignition Timing Control

The PCM contains the memory for basic ignition timing at various engine speeds and manifold air flow rates. It also adjusts the timing according to engine coolant temperature. The PCM detects misfiring by using the CKP sensor to monitor fluctuations in crankshaft speed. It will then set DTCs depending on how much misfiring occurs.