Most computer-controlled systems use knock sensors to retard timing when the engine is experiencing pinging or knocking.
A knock (detonation) sensor.
Obviously, a faulty knock sensor produces problems that appear to be ignition-system-related. If the knock sensor system does not provide an engine detonation signal to the PCM (powertrain control module), the engine detonates, especially on acceleration.
- The first step in diagnosing the knock sensor and knock sensor module is to check all the wires and connections in the system for loose connections, corroded terminals, and damage.
- With the ignition switch on, be sure that 12 volts are being supplied through the fuse to the knock sensor module.
- A quick check of a knock sensor is to watch the ignition's timing while the engine is running and the engine block is tapped with a hammer.
- The noise should cause a change in timing.
- The knock sensor can also be checked by tapping near the sensor and watching for an AC pulse on a DMM or lab scope.