DME 7.8 DME 7.8 0 · 0-47P0304

DME 7.8 DME 7.8 0 0-47P0304 511 Misfire, cylinder 4 Diagnosis conditions • A cycle of 1,000 crankshaft revolutions is evaluated (for misfire damaging to the TWC, 200 crankshaft revolutions). The misfire rates are compared with a threshold value. If the misfire rate is greater than the threshold value, a fault is recorded in the mem- ory. • The Check Engine Malfunction Indicator Lamp (MIL) is switched on and stays on when the misfire rate lies above the threshold value at which the emission limit values are exceeded during two consecutive driving cycles (in the case of EOBD 3 driving cycles). • If the misfire rate may lead to permanent damage to the TWC, the Check Engine MIL flashes. If the misfire rate is no longer reached during the first journey, the MIL goes out. If the rate is reached during the next journey, the MIL flashes. If this misfire rate is subsequently no longer reached, the MIL changes to a continuous light. Note! ♦When using a block heater (for heating coolant), start and driving off difficulties or misfiring can occur if the block heater was con- nected for less than 4 hours. ♦When the fuel tank is driven to empty, misfiring can occur. For this reason the fuel level in the tank is also stored in the memory when misfiring occurs. If the tank was nearly empty, there was probably no fault. Erase fault memory and road test vehicle. ♦In the event of a short circuit to B+ or ground in the oxygen sen- sors ahead of the TWC, the mixture becomes too lean or too rich. This can cause misfiring. If, in addition, an oxygen sensor signal fault ahead of the TWC is stored in memory, first correct this fault and then road test the vehicle. Possible fault cause ♦Fault in ignition system ♦Fault in injection system ♦Flat-base tappets (valve lift fault) ♦Mixture too rich ♦Mixture too lean 2470 P0304 0-47 page 1 Printed in Germany – 4, 2002 p0304