MEFI Fuel Injection
KS Circuit
MEFI 3 and 4
The ECM uses the knock sensor to detect detonation. The knock sensor is a piezoelectric device, or a crystal that creates a voltage when subjected to mechanical vibration. The knock sensor will produce a very low AC voltage signal anytime the engine is running. It will produce a larger AC voltage when detonation is present. When knock is detected the ECM can retard ignition timing to reduce knock. Little or no activity on the knock circuit at the ECM will set a DTC 44. If either knock sensor signal wire is routed too close to a spark plug wire, the ECM may translate the induced voltage as a knock signal, resulting in a false timing retard. This would cause an engine running problem that would look like the result of poor fuel quality.
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