1.3.11 Deactivation of the misfire detection (%DMDSTP)

Despite the already mentioned correction and adaptation methods, certain operating states exist for which deactivation of misfire detection is necessary to avoid misdetection. Misfire detection is suppressed under the following conditions:

• Engine start is immediately followed by unsteady crankshaft revolutions at low engine speed possibly leading to misdetections. Hence misfire monitoring is disabled until 1 camshaft revolution after engine speed reaches 400 rpm below warmed up idle speed.
• At low engine start temperatures misfire detection is deactivated for a calibrated time after engine start is finished
• Extremely rough road can induce drive train oscillations that lead to erroneous detection of misfire (misdetections). Misfire detection can be deactivated according to legislative requirements if misdetections could occur due to rough road.
• During camshaft sensor limp home condition, if camshaft control system errors are set
• During engine crankshaft sensor limp home condition, if an error crankshaft sensor or error reference mark is set
• If engine load is below zero load according to legislative requirements (e.g. overrun condition)
• If engine speed is below a calibrated minimum
• If engine speed is above a calibrated maximum
• during active torque intervention (e.g. Anti Blocking System, traction control and gear changes at wide open throttle)
• If the throttle valve's position has not been validated (limp home function is active)
• At extreme speed- and load fluctuations according to legislation.