500SL (129.067) V8-5.0L (119.972) (1993)
The ECM uses the following information:
^ Voltage supply (+)
^ Starter circuit
^ Engine temperature from coolant temperature sensor (B11/2)
^ Intake air temperature from intake manifold temperature sensor (B17/7)
^ Intake air mass from air mass sensor (B2/2)
^ Various information from the controller area network (CAN)
^ ABS/ASR information from ABS/ASR control module (N30/1)
^ Air/fuel mixture from oxygen sensor (G3/2)
^ ON signal for air injection
^ ON signal for exhaust gas recirculation (EGR)
CONTROL FUNCTIONS
Injection Base Quantity (Normal Driving) Function
During normal driving, the ECM uses the input devices to regulate injection frequency and timing. The two most influencing components are:
^
Air mass sensor with hot-wire (B2/2)
^
Engine RPM signal (TN)
Start And Warm-up Function
The start control provides for longer injection duration to enrich the air/fuel mixture. The final air/fuel mixture is dependent on the engine coolant
temperature. Mixture enrichment stops when the engine is at operating temperature.
Acceleration Function
During 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, 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 6300 ±50. After 10
seconds, the LH control module limits the engine to 6000 ±50 RPM.
Maximum Speed Function
The maximum vehicle speed is limited to 250 km/h (155 mph). If this speed is exceeded, the air/fuel mixture is leaned out and the camshaft timing
is advanced.
Self Adjusting Function
The ECM is adaptive to the changing engine operating parameters (wear and contamination of parts). It will adjust its calculations according to
assimilated input. Whenever the vehicle is started or driven, the ECM will use the value it has learned from the previous driving period.
Self Adjusting Oxygen sensor Function
The oxygen sensor (G3/2) operates in a similar fashion. It senses if the fuel mixture is rich or lean and the ECM 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 module receives a signal and goes into a "limp home mode." This pre-programmed mode will set the fuel injection frequency (opening