Valve Lifter Chattering

This is caused by dirt in the valve lifter. When the Check Engine MIL lights up, a chattering valve lifter may also occur for a certain time. The DME control module registers (sporadic) misfiring at one or more cylinders. The mixture adaptation values are normal.

Remedy:

1. Remove lifter bores, check for damage and blow out oil passages.
2. Replace all valve lifters (engine installed).
3. During the test drive, listen for valve lifter noises.