Abstract: A method is proposed for monitoring operations of an internal combustion engine to detect combustion misses for internal combustion engines having dual spark coils. A method is provided for the primary-side monitoring of the spark voltage and/or of the spark duration, and a method is provided for detecting irregular operations. If a faulty ignition is detected in one cylinder at one spark plug by monitoring the spark voltage and/or the spark duration, the second spark plug in this cylinder is then cut off (de-energized) and the reaction to this cut-off is monitored by means of the method for detecting irregular running. If the irregular running detection confirms faulty operation of the internal combustion engine, then the faulty ignition at the first spark plug of a cylinder was correctly recognized and appropriate emergency measures are introduced.

Abstract: Monitoring apparatus is provided for the ignition system of an internal combustion engine such as is provided in a motor vehicle, which is capable of detecting a variety of malfunctions of ignition under a variety of engine operating ranges, so that the catalyst used in the exhaust system of the engine can be protected by setting lambda=0 and/or cutting off fuel injection to an inoperative cylinder, in as many instances of malfunction as possible. Various methods of monitoring are available and are correlated for selection in accordance with the different operating ranges of the engine. The ignition spark duration and the ignition discharge voltage are measured for individual sparks on the primary side of an ignition coil and are compared with limit values for correct ignition, these limit values being selected from a memory in accordance with the particular range of operating conditions in which the engine is operating.

Abstract: A method of monitoring the operation of an internal combustion engine, such as is usable in a motor vehicle, combines the recognition of ignition failures with recognition of combustion failures. In one embodiment combustion failures are detected by the faltering of torque delivered by the engine. Ignition failures are electrically detected in terms of spark voltage or spark duration. In a first embodiment the rate of ignition and combustion failures is first compared with a predetermined threshold and if neither threshold is exceeded, the detection of an individual ignition failure is deemed plausible and is registered if detected. Only a failure rate in excess of a threshold results in cylinder-specific remedial measures to protect a catalyst in the exhaust system. In a second embodiment, unlike the first, only an ignition failure results in a cylinder-selective remedial action.

Abstract: Misfiring in internal combustion engines is detected by detecting the voltage induced in the primary winding of the ignition coil, and comparing it to a reference voltage which represents normal firing. The reference voltage preferably has a predetermined magnitude and a predetermined duration and the detected and reference voltage are compared so as to detect when the magnitude of the detected voltage falls below the predetermined magnitude before the end of the duration.