Chart C-5 - ESC System (Impulse Turbo): Notes

Knock sensor is used to detect engine detonation and ECM will retard electronic spark timing based on signal being received. Circuitry within knock sensor pulls 5-volt signal from ECM down to approximately 2.5 volts DC. Knock sensor produces an AC signal which rides back to ECM on 2.5 volts DC voltage. Amplitude and frequency are dependent upon knock level.

MEM-CAL used with this engine contains functions which were part of remotely mounted ESC modules used on other vehicles. ESC portion of MEM-CAL then sends signal to other parts of ECM which adjusts spark timing to retard spark and reduce detonation.

1. With engine idling, knock signal should not be present at ECM because detonation is not likely under a no-load condition.
2. Tapping on engine lift bracket should simulate a knock signal to determine if sensor is capable of detecting detonation. If no knock is detected, try tapping on engine block closer to sensor before replacing sensor.
3. If engine has an internal problem which is creating a knock, knock sensor may be responding to internal failure.
4. This test determines if knock sensor is faulty or if ESC portion of MEM-CAL is faulty. If it is determined MEM-CAL is faulty, ensure it is properly installed and latched into place. If not properly installed, repair and retest.