Below are extracts from the diagnostic sheets. If you would like a full copy, drop me an email: Function: To detect misfiring, the drop in engine speed which results when there is a partial lack of combustion at one or more cylinders is evaluated. A distinction is made between emission relevant misfiring after start-up, emission relevant misfiring during the journey and misfiring which is damaging to the TWC. (See fault text table on page P - 3). The engine speed is measured with an inductive sensor that is located above the ring gear on the flywheel. The ring gear is divided into three segments. For detection, the time between two segments is measured and the difference calculated. This difference is corrected by a mean value that is developed over several segments, to compensate for engine speed fluctuations caused by driving conditions. If the corrected value is above a specified threshold value which is dependent on engine speed and engine load, a misfire is detected. (See also Misfire detection description on pages B - 1 to B - 2). DTC No. - Fault conditions P0300 - Misfiring in several cylinders P0301 - Misfiring, cylinder 1 P0302 - Misfiring, cylinder 2 P0303 - Misfiring, cylinder 3 P0304 - Misfiring, cylinder 4 P0305 - Misfiring, cylinder 5 P0306 - Misfiring, cylinder 6 Fault area: – Mechanical causes – Fault in ignition system – Fault in injection system Combustion miss – Mixture too rich – Mixture too lean Possible mechanical causes of faults: 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.
