General description Magneti-Marelli engine management system (MM) installed on various models of Citroen, Peugeot, Fiat and some other cars. MMDCM 8P is an integrated system that controls the ignition coil primary, fuel supply and idle...
Ignition systems Setting the ignition timing The ignition timing setting on models equipped with the MM 8P system is not adjusted in the usual way. However, it is possible to adjust the curved ignition timing with the appropriate DTC...
Static (distributorless) ignition system (DIS) Ignition coil The ignition coil uses low resistance on the primary side of the ignition coil to increase primary current and primary energy. The amplifier limits the current in the primary winding to approximately 8 A...
Secondary winding of the ignition coil Voltage values of the secondary winding of the ignition coil (DIS) Element Voltage Ignition kV (idle) 8-20 kV Ignition kV (1500) 8-15 kV (max 4 kV between upper and lower cylinder) Slider kV Not used Acceleration kV +8...
Knock sensor (KS) (some models only) Since knocking can occur at different times in each individual cylinder, the MM 8P uses a knock control microprocessor (in the electronic control unit), to indicate the specific cylinder or cylinders where detonation...
Manifold absolute pressure (MAP) sensor The main engine load sensor is the intake manifold absolute pressure sensor (see illustration 12.14). The vacuum hose connects the intake manifold absolute pressure sensor and the intake manifold. The pressure is...
Throttle Position Sensor (TPS) Throttle position sensor (TPS) (see illustration 12.16) used to inform the ECU of throttle position and acceleration rate. The throttle position sensor is a three wire potentiometer. 12.16 Throttle position sensor (TPS)...
Vehicle Speed Sensor (VSS) Vehicle speed sensor (VSS) (see illustration 12.17) used to notify the ECU of vehicle speed. This Sensor is a Hall effect sensor and is located directly on the gearbox. 12.17 Vehicle speed sensor (VSS) Approximately 12...
Drives. Idle stepper motor Idle stepper motor (ISSM) (see illustration 12.19) is the actuator that the ECM uses to automatically control the idle speed at normal idle and while the engine is warming up. When closing the throttle valve is fixed in...
Fuel injection system The MM electronic control unit determines the moment and duration of injector opening depending on engine speed and engine load. This information is fed to the ECU from various sensors, such as the intake manifold...
Catalytic Converter and Emission Control System Fuel injection systems MM 8P, installed on vehicles equipped with a catalytic converter, have a closed circuit system, so that harmful emissions of exhaust gases can be minimized. Closed loop systems are equipped with...