Vauxhall Workshop Service and Repair Manuals

"MM 6JF" engine management system

The Z 13 DT engine is fitted with the "MM 6JF" engine management system. Multijet injection has been used for the first time on an engine from the Ecotec engine series.

The multijet injection system demands a lot from the engine management system. The engine management system has to continually correct the injection map, the number of injection processes and the quantity of diesel injected, depending on temperature, load and engine speed.

Components of the "MM 6JF" engine management system

Key to diagram L0010329

Electronic components of the Common Rail system

1. Rail pressure sensor 2. Pressure regulating valve 3. Injectors

Rail pressure sensor

The pressure sensor is bolted to the pressure accumulator on the timing side.

The pressure sensor measures the current pressure in the pressure accumulator and sends a voltage signal to the engine control unit.

Voltage [V] Rail pressure [bar]

Pressure regulating valve

The pressure regulating valve is bolted into the pressure accumulator on the transmission side.

An electromagnet in the pressure regulating valve is actuated by the engine control unit; this opens a valve ball against spring force.

Technical data:

Injectors

Injectors (injector nozzles with electronically controlled valves) carry out injection processes at the right time and with exactly the right amount of fuel.

The injectors are actuated by the engine control unit up to five times per expansion stroke.

1. Pilot injection 2. 1st main injection 3. 2nd main injection 4. 3rd main injection 5. Secondary injection

Crankshaft pulse generator

When turning, the crankshaft pulse generator induces a voltage in response to the generator disc teeth. The sine curve indicates the AC voltage which arises in the process. Its frequency (oscillation frequency) is dependent on the rotational speed of the pulse wheel.

The pulse generator disc is attached to the rear of the flywheel.

Teeth of the pulse generator disc Signals to the engine control unit 1. Crankshaft pulse generator 2. TDC of the pulse generator disc 3. Signal point of TDC position 4. Pulse generator disc

Camshaft sensor

The camshaft sensor is installed in the camshaft housing and scans the position of the exhaust camshaft.

Using Hall-effect pickups on the camshaft, the position of the camshaft is recorded and the signal sent to the engine control unit.

Camshaft position sensor Signal diagram of camshaft sensor

Air mass meter

The air mass meter sits between the air filter and the air intake pipe, has two tasks and sends signals to the engine control unit.

1. Measuring the quantity of intake air
Voltage [V] Air flow rate [kg/h]

2. Measuring the intake air temperature
1. Resistance [ohms] 2. Temperature [°C]

Coolant temperature sensor

The coolant temperature sensor is installed in the thermostat housing. The resistance of this sensor decreases as temperature increases.

Resistance [ohms] Temperature [°C] Coolant temperature sensor

Charge pressure sensor

The charge pressure sensor is installed in the inlet manifold. The output signal to the engine control unit is 0 to 5 volts.

Voltage [V] Charge pressure [kPa] Charge pressure sensor