Abstract: A method of controlling engine operation in a vehicle in response to a misfire of one of a plurality of engine cylinders fueled through fuel injectors. The vehicle includes a fuel vapor storage canister. The method includes disabling at least one of the fuel injectors, using an open loop to control fuel delivery by the injectors to the cylinders, and disabling purging of the canister. The disabling and using steps are performed while the misfire continues.

Abstract: A method and an apparatus for diagnosing the Ignition-Off Timer of an internal combustion engine. This invention monitors the initial operation of the Ignition-Off Timer each time it is enabled in order to detect a variety of malfunctions. The malfunctions are detected by comparing the operation of the Ignition-Off Timer to various reference values. Upon diagnosis of the Ignition-Off Timer, its condition is reported to the diagnostic management system, which determines whether and when a malfunction indicator is energized.

Abstract: A diagnostic routine is used for testing an oxygen sensor heater of an internal combustion engine. The oxygen sensor heater is preheated prior to testing. A voltage signal from the oxygen sensor is measured after a predetermined period of time. If the voltage signal is greater than a threshold value after the predetermined period of time has elapsed, the oxygen sensor heater is considered to have failed the diagnostic routine. If the voltage signal is not greater than the threshold value after the predetermined period of time has elapsed, the oxygen sensor is considered to have passed the diagnostic routine.

Abstract: Engine combustion malfunctions are detected and the responsible cylinder identified by an approach appropriate to the engine operating point by monitoring change in engine speed in a manner insensitive to engine output shaft tooth-to-tooth spacing variations, substantially linear changes in engine speed, and driveline ringing, such as from rough roads or a previously detected misfire. Multiple misfires may be detected in a single engine cycle.

Abstract: A motor vehicle engine includes an operator controlled fuel injection enabling switch effective to disconnect electric fuel injection apparatus from an electric power source and thus initiate the cessation of engine operation when deactivated. However, the spark ignition system is still powered through an oil pressure switch so as to continue engine operation for a few extra crankshaft rotations to reduce the unburned fuel in the intake passage as the engine stops and thus reduce throttle bore coking. In a vehicle having a fuel pump relay activated by the fuel injection enabling switch with contacts connected across the oil pressure switch, the invention may be obtained by changing the power connection of the spark ignition system from the fuel injection enabling (ignition) switch to the fuel pump relay.