STRATEGY FOR A FAIL-SAFE ELECTRONIC DIESEL CONTROL SYSTEM FOR PASSENGER CARS

Mechanical control systems for diesel engines are reliable and exhibit a low failure rate. However, rising demands for improved functional characteristics and closer tolerances require electronic diesel control. The electronic diesel control (EDC) offers functional advantages over mechanical controls. In order to obtain a fail-safe system it is necessary to detect defects in sensors, in the digital processor, in actuators and in the overall system. The failure of exhaust gas recirculation is uncritical, the failure of start of injection control needs countermeasures to avoid a damage of the engine. Without countermeasures fuel delivery control failure may lead to safety risks. All required countermeasures will be explained in detail.