Injection Control

OPERATION
The ECUs contain several programs and functions which are briefly described below.

The ECUs use the following information:
^ Voltage supply (+)
^ Starter circuit
^ Engine temperature from coolant temperature sensors (B11/9 or B11/10)
^ Intake air temperature from intake manifold temperature sensors (B17/5 or B17/6)
^ Intake air mass from air mass sensors (B2/3 or B2/4)
^ Various information from the controller area network (CAN)
^ Air/fuel mixture from oxygen sensors (G3/3 or G3/4)

CONTROL FUNCTIONS

Injection Base Quantity (Normal Driving) Function
During normal driving, the ECUs use the input devices to regulate injection frequency and timing. The two most influencing components are:
^ Air mass sensor with hot-wire (B2/3 or B2/4)
^ Engine RPM signal (TN)

Start And Warm-up Function
The start control provides for longer injection duration to enrich the mixture. The final air/fuel mixture is dependent on the engine coolant temperature. Mixture enrichment stops when the engine is at operating temperature.

Full Load And Acceleration Function
During full load or acceleration, a richer air/fuel mixture is provided to achieve maximum engine power. This will also keep combustion heat and catalytic converter temperature at an acceptable level.

Deceleration Shut-off Chart:

Deceleration Shut-off Function
During deceleration, some or all the fuel injectors are turned off (in all gears) if engine temperature is above 70 °C (158 °F). The engine speeds for injection cut-off/ restart are shown in the chart.

Maximum Engine RPM Function
At excess RPM the fuel injectors are turned off to keep the engine from overrevving. The momentary engine RPM limit is 6200 ±50. After 5 seconds, the LH control units limits the engine to 6000 ±50 RPM. Below 44 km/h (28 mph) the engine speed is limited to 5100 RPM.

Self Adjusting Function
The ECUs are adaptive to the changing engine operating parameters (wear and contamination of parts). They will adjust the calculations according to assimilated input. Whenever the vehicle is started or driven, the ECUs will use the values they have learned from the previous driving period.

Self Adjusting Oxygen sensor Function
The oxygen sensors (G3/3 and G3/4) operate in a similar fashion. They sense if the fuel mixture is rich or lean and the ECU adjusts the oxygen sensor control accordingly. This self-regulating function keeps the air/fuel mixture at a constant midpoint. Therefore, the need to adjust CO content is eliminated and no more possible.

Safety Fuel Shut-off function
If due to a malfunction, the throttle valve opens further than the position called for by the accelerator pedal (cruise control not in operation), The LH control units receive a signal and go into a "limp home mode." This pre-programmed mode will set the fuel injection frequency (opening duration) so the engine can't exceed 1300 RPM and the vehicle can be slowly driven to the repair shop.

Diagnostic Function
If an LH control unit detects a specific fault more than 4 sequential times (ignition switch turned ON and OFF), a fault code is stored in the control unit memory. Only malfunctions which prevent/severely influence starting or operating of the fuel injection system are immediately stored in the fault memory.

A "CHECK ENGINE" light will inform the operator of an emission related problem. It illuminates when a certain malfunction in the engine management system is detected. The operator should bring the vehicle to the repair shop as soon as possible.

The malfunction memory can be accessed via the diagnostic connector (X11/4). The malfunction memory is not erased when disconnecting the battery.