M2.8.1 Sequential Multiport Fuel Injection System
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WIRING DIAGRAM
Motronic 2.8.1 Sequential Multiport Fuel Injection System: Component Location:
COMPONENT LOCATION VIEW
Motronic 2.8.1 Sequential Multiport Fuel Injection System: Component ID:
COMPONENT ID
22a Fuse board behind the access panel in the glove box.
76 Idling speed increase contact in transmission range switch 239 adjacent to the selector lever.
102 Fuel pump relay in main fuse box behind the glove box.
110 Tachometer in the main instrument display panel.
132 Speed sensor in the speedometer in the main instrument display panel.
136 Oxygen sensor on the exhaust pipe adjacent to the manifold.
156 A/C compressor relay in main fuse box in front of the battery.
157 Spark plugs, on the top of the engine, under the cover.
159 Distribution terminal (+15 circuit), in main fuse box behind the glove box.
171 Antifrost thermostat on the evaporator casing below the windscreen on the right-hand side.
178b Knock sensor for cylinder bank 2, on the engine block.
202 Engine coolant temperature sensor on the intake manifold flange between cylinders 2 and 3.
203 Throttle position sensor on the throttle body.
205 Mass air flow sensor on the intake manifold after the air cleaner.
206a-f Injectors on the intake manifold.
210 EDU trip computer in the main instrument display panel.
229 Main relay, engine management system, in main fuse box behind the glove box.
230 Distribution terminal (+30 circuit) in main fuse box behind the glove box.
231 Distribution terminal (+54 circuit), in main fuse box behind the glove box.
239 Transmission range switch (automatic transmission) adjacent to the selector lever.
271 Heating element, oxygen sensor, integrated into the sensor.
272 Idle Air Control valve, in the middle of the intake manifold.
289 Control module, anti-theft alarm, on the right-hand side under the dashboard behind the knee shield.
321 EVAP canister purge valve in the right-hand wheel housing.
323 Fuel pump in fuel tank under luggage compartment floor.
324 Relay, secondary air injection pump, in main fuse box in front of the battery.
345 Crankshaft position sensor, behind the belt pulley on the oil pump housing.
407 Intake air temperature sensor, in engine bay on the intake manifold.
445 (H16-1) Diagnostics test socket, below the steering wheel.
454 Control valve, inner VIM flap, on the intake manifold.
455 Control valve, outer VIM flap, on the intake manifold.
507 TCS Control module, V6, under left-hand front seat.
510 Motronic 2.8.1 control module in the engine bay behind the bulkhead partition.
515 Oxygen sensor, cylinder bank 1, in the exhaust manifold.
516 Knock sensor for cylinder bank 2, on the engine block.
552 Ignition coil module, on left-hand side of engine.
555 Camshaft position sensor, adjacent to the camshaft sprocket.
583 Control module, anti-theft alarm with immobilizer, under the dashboard on the right-hand side behind the knee shield.
2-Pin Connectors
H2-93 On a bracket to the left of the rear exhaust manifold.
H2-94 On the front left-hand side of the engine.
3-Pin Connectors
H3-20 Behind the main instrument display panel beside the speedometer (ME).
H3-27 On a bracket just behind the radiator, at bottom.
4-Pin Connectors
H4-4 Beside the fuel pump under the luggage compartment floor.
H4-23 On a bracket just behind the radiator, at bottom.
H4-24 On a bracket to the left of the rear exhaust manifold.
H4-27 On a bracket to the left of the rear exhaust manifold (blue).
H4-28 On the front left-hand side of the engine.
6-Pin Connector
H6-5 In the front right-hand corner behind the light cluster beside the washer fluid reservoir.
10-Pin Connectors
H10-1 Under the dashboard to the right, behind the radio compartment.
H10-15 Behind the left-hand headlamp.
H10-25 Behind the left-hand headlamp.
24-Pin Connector
H24-2 Behind the left-hand headlamp on a bracket.
25-Pin Connector
H25-1 Instead of the anti-theft alarm's control module.
70-Pin Connector
H70-1 In the engine bay, behind the bulkhead partition.
Grounding Points
G5 Grounding point, rear seat, under the left-hand part of the seat.
G8 Grounding point, dashboard, beside the front left-hand loudspeaker socket.
G7 Grounding point, engine, at the rear of the engine on a sheet metal bracket below the intake manifold.
DESCRIPTION OF OPERATION
The Motronic 2.8.1 is an engine management system for V6 engines. It controls both ignition timing and fuel injection from a single control module.
The Motronic system has sequential multiport fuel injection and individual control of ignition timing if knocking occurs in any of the cylinders. This function is adaptive.
Expressed in simplified terms, it could be said that the Motronic system is a combined electronic fuel injection system and electronic ignition system with knock sensor.
The fuel injection system has an advanced function in that injection is sequential. The ignition power module is integrated into the control module.
M2.8.1 Control Module
Control module 510 monitors and controls a number of functions.
The Control Module Obtains Information From:
^ Speedsensor 132
^ Oxygen sensor, cylinder bank 2, 136b
^ A/C status via antifrost thermostat 171
^ Knock sensor, cylinder bank 2, 178b
^ Engine coolant temperature sensor 202
^ Throttle position sensor 203
^ Mass air flow sensor 205
^ Selector lever position (automatic transmission) 239
^ Crankshaft position sensor 345
^ Intake air temperature sensor 407
^ TTS control module 507
^ Oxygen sensor, cylinder bank 1, 515
^ Knock sensor, cylinder bank 1, 516
^ Camshaft position sensor 555
The Control Module Supplies Information To:
^ Fuel pump relay 102
^ A/C compressor relay 156
^ Throttle position sensor 203
^ Injectors 206
^ EDU control module 210
^ Main relay 229
^ Idle air control valve (IAC) 272
^ EVAP canister purge valve 321
^ Secondary air injection control valve 325
^ Secondary air injection pump 326
^ Data link connector 445
^ Variable intake manifold boost pressure control valves 454, 455
^ Ignition coil unit 552
^ Engine speed
Power Supply
Current (+30 circuit) is supplied via fuse 23 to pin 18 of the control module. This current is used for the control module's memory.
Current (+15 circuit) is supplied to control module pin 27 via distribution terminal 159. When the ignition switch is turned to the Drive position, main relay 229 is connected to ground via pin 46 of the control module. The relay then operates and supplies the control module with current (+30 circuit) on pin 37.
Engine Speed
Engine speed data is sent via pin 4 to tachometer 110 in the main instrument display panel and to the TTS control module.
Air Conditioning, A/C
The Motronic control module obtains information from the A/C switch/ACC unit as to whether the A/C system is engaged. This information is received via pressure switch 166 and antifrost thermostat 171.
The control module then grounds relay 156 and the compressor starts. When the compressor is engaged, the control module compensates for the increased load on the engine caused by the compressor.
If the coolant temperature rises to 115°C (239 °F), the EDU control module breaks the connection and the compressor stops.
Oxygen Sensors 136b And 515
The oxygen sensors, 136b for cylinder bank 2 and 515 for cylinder bank 1, are mounted on the exhaust pipe. Their task is to provide the control module with data on the composition of the exhaust gases (oxygen content). Since the sensors continuously measure the oxygen content of the exhaust gases, the control module can adjust the fuel-air mixture and bring it as close as possible to lambda = 1.
Knock Sensors 178b And 516
The knock sensors, 178 for cylinder bank 2 and 516 for cylinder bank 1, sense the engine's tendency to knock and convert any knocking into a voltage signal. The control module processes the voltage signal and adjusts the ignition timing to achieve optimum performance and minimum emission levels.
Temperature Sensor 202
The coolant temperature sensor is of NTC type and provides the control module with data about the temperature of the coolant.
If there is an open circuit in the sensor, the control module simulates a substitute value.
Throttle Position Sensor 203
The throttle position sensor provides information on the position of the throttle butterfly valve. The sensor is a potentiometer which provides continuous data from idling speed (closed throttle) to wide open throttle.
Mass Air Flow Sensor 205
The mass air flow sensor measures the air mass consumed by the engine, which is proportional to the engine load.
In the event of a malfunction, the control module uses the data obtained from the throttle position sensor.
Oxygen Sensor Preheating Element 271
To work effectively, the sensor must be warm. The sensors are therefore equipped with an integrated heating element so that they will attain working temperature as quickly as possible. This is known as preheating.
The heating element is supplied with current via fuse 28. Disconnection of preheating effected by control module 510.
Idle Air Control Valve 272
The idle air control valve is controlled by the control module, which regulates the opening angle of the butterfly valve in order to maintain the idling speed constant.
For instance, this means that the butterfly valve opens on engagement of the A/C in order to compensate for the increased load on the engine.
Should a fault arise in the circuit, the butterfly valve will be automatically set to a constant idling speed of at least 1000 rpm.
EVAP Canister Purge Valve 321
The EVAP canister purge valve, located in the engine bay on the right-hand side, is controlled by the control module on the basis of engine temperature, rpm and load.
The valve opens under specific conditions and admits fuel vapours from the evaporative emission canister to the intake manifold where they are burnt together with the regular fuel-air mixture.
Crankshaft Position Sensor 345
The control module obtains information on the position and speed of the crankshaft from the crankshaft position sensor.
The sensor consists of a slotted ring on the crankshaft at the flywheel end and an inductive sensor mounted in the engine block.
The inductive sensor works somewhat like a small alternator, the sinusoidal voltage and frequency of which increase with increasing rpm. The sinusoidal voltage alternates between positive and negative polarity, which is achieved by means of teeth on the slotted ring.
This alternating polarity is utilized by the control module to ascertain the speed of the engine and to identify which cylinder's piston is at or approaching TDC.
If the sensor is defective, the engine will not start.
Camshaft Position Sensor 555
The camshaft position sensor is of the Hall sensor type. It senses the position of the camshaft for cylinder 1 by means of a ridge on the camshaft. When this ridge passes the sensor, the control module input is grounded.
Temperature Sensor 407
The intake air temperature sensor is located in the intake manifold. It is of NTC type and sends the control module a continuous signal relating to the air temperature.
Low temperature = High voltage
High temperature = Low voltage.
On the basis of the current air pressure (from manifold absolute pressure sensor 431) and the temperature of the intake air, the current air mass can be determined.
Control Valves 454 And 455
To achieve even and high torque over a wide engine speed range, the engine is equipped with a variable intake manifold.
Using the control valves, which are regulated by the control module, three different intake manifold lengths can be obtained.
Ignition Coil Module 552
The ignition system is inductive but has no distributor. The module has three ignition coils.
Check Engine
In the event of a fault in the engine management system, or if the emission values are incorrect, the CHECK ENGINE lamp (MIL) in the EDU control module will light up.
Data Link Connector 445
The data link connector for an ISAT scan tool is located below the steering wheel. It is also connected directly to fuel pump relay 102.
FAULT DIAGNOSIS HINTS
The ISAT scan tool is used for fault diagnosis and obtaining readouts of diagnostic trouble codes.