Checking Motronic Timing Advance (engine code 9A)No specifications are given for precisely checking the amount of timing advance on CIS-E Motronic systems. Timing advance is based on engine rpm (the Hall sender), engine load (the air flow sensor potentiometer signal), and engine knocking (the knock sensors and reference sensor). In general, the operation of the timing advance function can be checked using a timing light to check that the timing mark moves when engine idle is increased. If the timing does not advance at all, first check the knock sensor resistance and mounting bolt torque as described in 4.5 Checking and Replacing Knock Sensor, then the reference sensor, air flow sensor potentiometer, and system wiring as described in 4.6 Troubleshooting Knock Sensor System. If torque and resistance are within specification and there are no faulty components or breaks in the wiring, then the Motronic control unit is probably faulty. |
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