ME-SFI idle speed control function - GF07.61-P-2008G
ENGINE 273 in MODEL 463.202/222/236/237 up to 31.5.12 as of model year 2009/YoM 08
Function requirements for idle speed control of the ME gasoline injection and ignition system (motor electronics) (ME), general points
- Circuit 87M ON (engine control ON)
- Engine running
- Accelerator not operated
ME-SFI idle speed control, general points
The idle speed control regulates and stabilizes the idle speed depending on operating conditions and engine load.
For idle speed control, the ME-SFI [ME] control unit reads the following sensors and signals:
- Crankshaft Hall sensor, engine speed
- Hot film MAF sensor, engine load
- Coolant temperature sensor
- Gear range via the drive train CAN
- AAC [KLA] control and operating unit, status of the air conditioning via the interior CAN and drive train CAN
ME-SFI idle speed control, function sequence
The ME-SFI [ME] control unit regulates the idle speed via the throttle valve actuator and adapts the injection time of the fuel injection valves (Y62) according to variations in the air mass. To assist the idle speed control, the ME-SFI [ME] control unit can shift the ignition angles of the ignition coils towards "retarded" by up to a 36° crank angle (KW), or towards "advanced" by up to a 20° crank angle.
Adjusting the ignition angle enables a faster response than adjusting the throttle valve.
The ME-SFI [ME] control unit regulates the idle speed in the following operating and engine load conditions:
- Warm-up phase function sequence
- Selection of gear range "D" or "R" function sequence
- Refrigerant compressor (A9) cut-in function sequence
- Battery undervoltage function sequence (G1)
- Purging function sequence
Warm-up phase function sequence
In the warm-up phase, the ME-SFI [ME] control unit controls the idle speed according to coolant temperature, in order to bring the catalytic converters more quickly up to operating temperature after engine start.
Additional function requirements in the warm-up phase are:
- Coolant temperature T < 40 °C
- Gear range "N" or "P" engaged
The ME-SFI [ME] control unit raises the idle speed to about 1100 to 1300 rpm for about t = 20 s.
After this time has elapsed, the idle speed is increased at a coolant temperature of < 70°C in line with the temperature for approx.
t = 50 seconds by approx. 50 to 100 rpm.
Gear range selection "D" or "R" function sequence
When gear range "D" or "R" is selected, the idle speed is set to a lower value to reduce the tendency of the vehicle to creep forward.
To do this, the ME-SFI [ME] control unit evaluates the "gear range engaged" signal from the electric controller unit (VGS). Y3/8
Refrigerant compressor cut-in function sequence
To ensure that the engine idle speed does not drop when the refrigerant compressor engages, the AAC [KLA] control and operating unit first sends a status signal to the ME-SFI [ME] control unit.
The ME-SFI [ME] control unit adapts the idle speed appropriately.
Battery undervoltage function sequence
If the ME-SFI [ME] control unit detects an undervoltage through "circuit 30", the idle speed is raised by about 100 rpm when gear range "D" or "R" is selected, until the ignition is switched off.
Purging function sequence
The idle speed control prevents any change in the engine speed due to purging.
Diagnosis:
The basic setting of the idle speed can be read out and adjusted with the Diagnosis Assistance System (DAS.
| Component description for ME-SFI [ME] control unit | N3/10 | GF07.61-P-6000G | |
| Automatic air conditioning control and operating unit, component description | N22 | GF83.40-P-3000G | |
| Component description for electronic ignition/starter switch control unit (EIS) | N73 | GF80.57-P-6000G | |
| Component description for fully integrated transmission control unit | Y3/8n4 | GF27.60-P-5165GGA |