Timing Seems Out of Range For Conditions VAST or ESA

In some cases, driveability symptoms or a check of timing reveal advance which is out of range for input conditions. This situation could be caused by incorrect sensor information reaching the ECU.

An example of this type of problem can be illustrated by a manifold pressure sensor which is out of range low. Lower than normal voltage from the sensor would indicate a light load condition to the ECU. The ECU responds to light load operation by advancing the timing. If the vehicle is being operated under moderate to heavy load with too much spark advance, detonation will likely result.

When this type of condition is suspected, it is recommended to perform a standard voltage check of all major sensor inputs to the ECU. If any sensor is found out of normal range, it is a likely cause of the problem. The subject of sensor signal values is addressed in, "Electronic Engine Controls."

Adjustment Of Initial late design check connector

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