Knock control: Control: Evaluation
The signal that has been bandpass filtered is compensated with the current knock adaption and is then analyzed for any knocking. To further reduce risks, ECM only "listens" for knocks within a certain number of crankshaft degrees after the spark was fired, i.e. when knocking usually occurs. The signal is evaluated for knock intensity and a raw value for knocking is obtained. This raw value is further processed as a different intensity of the raw value is allowed at different engine loads/engine speeds.
The processed raw value can then result in one of the following countermeasures:
- Ignition retardation
- Ignition retardation and fuel enrichment
- Ignition retardation, fuel enrichment and torque reduction