1 | Fault code | Misfire, total Misfire, cylinder 1 Misfire, cylinder 2 Misfire, cylinder 3 Misfire, cylinder 4 Misfire, cylinder 5 Misfire, cylinder 6 Misfire, cylinder 7 Misfire, cylinder 8 Tank level too low Tank level too low |
2 | Fault storage Activation of malfunction indicator lamp for engine diagnosis (EURO3/4) or CHECK ENGINE (MIL) | after the end of the test period and faults A misfire (emission limit) after two successive driving cycles with faults B misfire "damaging to TWC" Malfunction indicator lamp is activated immediately with combustion misfires |
3 | Frequency of the test | continuous |
4 | Checked signal or status | Number of detected combustion misfires (detection via smooth operation assessment) |
5 | Limits | A maximum of 20 combustion misfires within 1000 engine rotations A maximum of 4 - 35 combustion misfires within 200 engine rotations (map dependent on engine speed and load; e.g. 4 misfires starting from medium engine speed and load, 35 misfires when idling without load) |
6 | Test prerequisites | - engine speed approx. 450 - 6000 rpm - change in engine speed less than 1900 rpm per second - change in load < 50 % per second - engine started before at least 5 s - no ESP control intervention function - sensor wheel adaptation already performed in deceleration - no road bumps detected (determined via CAN of ASR/ESP control module, by comparing the wheel speeds) - no fault in camshaft Hall sensor signal - no inertia fuel shutoff |
7 | | If too many combustion misfires occur at one cylinder, the cylinder is turned off (cylinder-selective fuel cut-off). Misfires through faults in the ignition system If ignition cannot be performed, this leads to combustion misfires. If, in addition to the misfire faults, other faults in the ignition system are stored, start with troubleshooting in the ignition system. Maximum permissible smooth operation deviation at one cylinder approx. 3 ms2. If this value is exceeded, determine the ignition circuit causing this by turning off the ignition circuit as follows: 1. Turn off one ignition circuit (a or b) with STAR DIAGNOSIS/HHT. 2. Monitor smooth operation value for the cylinder in question. - Value changes minimally (up to approx. 2 ms2): the ignition circuit still switched on has no faults. - Value changes considerably (more than approx. 2 ms2): the ignition circuit switched on has faults. Check spark plug, ignition cable and ignition coil. |
| Misfires due to fuel starvation If combustion misfires are detected, the fault code or is also output with too little fuel. This information indicates combustion misfires due to fuel starvation. Misfires after cylinder cut-out system OFF After turning off the cylinder cut-out system, the system monitors via misfire detection whether all the intake and exhaust valves are open again. Misfires due to other causes Combustion misfires may be caused by many faults in the injection system. Usually in this case other component or function faults are stored, in addition to the misfire fault. Faults in the engine mechanics may even be the cause. |