Component description for ME-SFI [ME] control unit

D07.61-1140-01

Illustrated on model 906

N3/23 ME-SFI [ME] control unit

Location

The ME-SFI [ME] control unit is located on the intake manifold.

Task

The input signals appropriately controls the following functions:

- Ignition system, diesel fuel injection system

- Accelerator pedal module (B37/3) (for model 639 (B37/4)), idle speed control

- Diagnosis and fault storage

- Drive authorization system stage 3 (FBS 3) and immobilizer

D07.61-1119-01

Design

1 Coupling F (on-board)

2 Coupling M (engine-side)

N3/23 ME-SFI [ME] control unit

Contacting takes place on the engine and vehicle side over 2 couplings locked with slides. Cooling fins on the upper side provide the necessary rejection of heat. Vibrations are suppressed by rubber brackets.

Function

Control of fuel injection system

The ME-SFI [ME] control unit actuates the injection valves (fuel injection valve for cylinder 1 (Y62/1), fuel injection valve for cylinder 2 (Y62/2), fuel injection valve for cylinder 3 (Y62/3), fuel injection valve for cylinder 4 (Y62/4), fuel injection valve for cylinder 5 (Y62/5) and fuel injection valve for cylinder 6 (Y62/6)) individually, according to the input signals and the performance maps stored in the ME-SFI [ME] control unit, according to the firing order (sequential). The ME-SFI [ME] control unit calculates the opening times (injection duration) of the injection valves.

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Control of ignition system

The ME-SFI [ME] control unit actuates the ignition system in line with the input signals and the performance maps stored in the ME-SFI [ME] control unit. The ME-SFI [ME] control unit calculates the ignition timing and regulates the antiknock control (AKR).

Control of idle speed control

The throttle valve actuator (M16/5) is actuated on the basis of the input signals and the performance maps stored in the ME-SFI [ME] control unit.

Diagnosis and fault memory

The ME-SFI [ME] control unit checks its inputs and outputs for plausibility and recognizes possible faults. The following faults can be differentiated:

- Fault permanently present

- Loose connection fault, which occurred during a drive

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The faults are deleted after discontinuity of the circuit 30 in

the ME-SFI [ME] control unit.

FBS 3 and immobilizer

The ME-SFI [ME] control unit is always equipped with an immobilizer. If the vehicle is sealed, the EIS control unit (N73) sends information to the ME-SFI [ME] control unit via the Control Area Network (data bus/CAN bus) (CAN), which reacts by locking the engine control (injection).

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Only if the vehicle is opened up again with the authorized key and the EIS control unit sends a respective information to the ME-SFI [ME] control unit via a CAN, can the engine be started (start enable).

 The ME-SFI [ME] control unit is on functional with a CAN and the FBS 3.

Engine speed signal

The ME-SFI [ME] control unit generates the short circuit proof engine speed signal "TNA" from the signals from the crankshaft sensor (B70) and passes it on to further control units.

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Actuations with STAR DIAGNOSIS

Functions can be actuated specifically for diagnostic purposes. These are listed in a menu point.

Variant coding

The ME-SFI [ME] control unit can be adapted to the different vehicle versions and vehicle equipment. This variant coding takes place with Star Diagnosis. Variant coding can be used, for example, to code the following vehicle versions and equipment variants:

- Vehicle model

- National version

- Transmission version

Fuel consumption signal

The consumption signal is calculated from the injection duration and subsequently transmitted via the CAN to the trip computer in the instrument cluster (A1).

Start recognition

The ME-SFI [ME] control unit is informed over the initiated starting procedure by the CAN message "circuit 50 ON". This is required, for example to trigger the start quantity control, starter control, post-start enrichment and for determination of the ignition timing for starting.

Computer power-down

For "circuit 15 OFF", the ME-SFI [ME] control unit performs a computer power-down, whereby certain data memories are updated (e.g. the fault memory). The run-on time with a warmed up engine is approx. 5 s, but may be extended to several minutes by various functions. After the fault memory has been cleared, the run-on time must expire.

 Various engine operating information is transmitted via CAN by the ME-SFI [ME] control unit to the instrument cluster and to other control units that are connected to the CAN data bus.