LH Fuel System 2.4 : I16 Lambda
LH Fuel System Diagrams:
LH Fuel System Components:
Locations of components
1 Battery
On the left-hand side of the engine compartment
7 Earthing point
On the left-hand wheel housing
8 Lighting relay
In the electrical distribution box in the engine compartment (1988) behind the left-hand headlamp
22A Fuse board
Behind the access panel in the glove compartment
47A Fuel gauge
In the combined instrument
47C Coolant temperature gauge
In the combined instrument
47P CHECK ENGINE warning lamp
In the combined instrument
57 Three-pole connector
In the engine compartment, at the windscreen wiper motor
59 Two-pole connector
Two in the engine compartment at the windscreen wiper motor
One on the right-hand side of the engine compartment, at the intake manifold
One at the fuel pumps, under the luggage compartment floor
60 Single-pole connector
One on the left-hand side of the engine compartment, at the bulkhead
One at the engine manifold, next to the Lambda sensor
65 Earthing point
Under the back seat
67 Six-pole connector
In the engine compartment, at the windscreen wiper motor
75 Distribution block
Forward of the battery
76 Switch for raising the engine idling speed, auto
Under the centre console, at the gear selector lever, in gear selector switch 239
101 Feed pump
In the fuel tank, underthe luggage compartment floor
102 Fuel pump relay
In the electrical distribution box behind the glove compartment
103 Fuel pump
In the fuel tank, under the luggage compartment floor
122 Eight-pole connector
Two behind the combined instrument
123 Four-pole connector
In the engine compartment, at the windscreen wiper motor
132 Sensor for the speed transmitter
In the speedometer, in the combined instrument
136 Lambda sensor
On the engine manifold
147 Ignition pulse amplifier
In the electrical distribution box behind the glove compartment
156 Relay for the AC and ACC radiator fan
In the electrical distribution box, behind the glove compartment
159 Distribution terminal +15
In the electrical distribution box behind the glove compartment
176 Control unit, EZK ignition system
1987: under the facia, to the left of the steering column (behind the knee shield)
1988: under the left-hand front seat
200 Control unit, LH fuel system
On the left-hand side of the bulkhead between the engine compartment and the passenger compartment
201 Engine earthing point
At the engine lifting lug
202 Engine temperature transmitter
On the intake manifold flange, between cylinders 2 and 3
203 Throttle angle transmitter
On the intake manifold
204 Test connector
On the left-hand side of the engine compartment, on the bulkhead
205 Air mass meter
on the hose between the air cleaner and the engine intake manifold
206 Injection valves
On the underside of the intake manifold
210 EDU trip computer
In the combined instrument
211 Earthing point
on the gearbox
229 Main relay (fuel injection system)
In the electrical distribution box behind the glove compartment
230 Distribution terminal +30
In the electrical distribution box behind the glove compartment
231 Distribution terminal +54
In the electrical distribution box behind the glove compartment
257 Earthing point
On the alternator bracket
270 Shift-up indication relay
In the electrical distribution box behind the glove compartment
271 Lambda sensor preheater
On the engine manifold
272 Engine idling speed adjustment
In the centre of the intake manifold
285 Lambda sensor fuse
In the engine compartment, at the windscreen wiper motor
321 Charcoal filter
In the right-hand wheel housing
322 Connector, auto./man., LH 2.4
one two-pole and one three-pole, on the left-hand side of the bulkhead between the engine compartment and the passenger compartment
323 Fuel pump with integrated feed pump
In the fuel tank, under the luggage compartment floor
Operation
Some sixteen-valve engines with Lambda are equipped with version 2.4 of the Bosch LH Jetronic fuel injection system, which is an update of version 2.2. LH is an abbreviation of Luftmassenmesser Hitzdraht (Air mass meter with hot filament). The fuel injection system is controlled and monitored by control unit 200, which includes a microprocessor.
A number of new features have been introduced, such as:
- Adaptive Lambda control system
- AIC (Automatic Idle Control) valve with built-in "limp-home" function. When necessary, the valve provides a high, fixed idling speed of 1200 r/min.
- Adaptive idle control system. Normal changes are compensated for automatically. The idling speed is controlled by means of valve 272.
- Built-in deceleration function. During overrun braking, it cuts off the fuel supply within certain engine speed ranges.
- A new, electrically-operated relief valve (321) for the charcoal canister. Controlled by signals from the control unit. The charcoal in the canister absorbs fuel fumes in the vent line from the tank.
- Built-in fault diagnosis system. Gives fault codes via the CHECK ENGINE lamp.
The system receives a positive supply from fuse 22
when the ignition switch is in the start or drive position, and a constant supply from +30 to relays 229 and 102.
On the basis of the data stored in the control unit and the incoming information from various sensors, the control unit calculates and controls the opening times of the electrically operated fuel injection valves (206).
Control unit 200 receives information on the engine speed by sensing the pulses from the ignition system.
Throttle valve angle transmitter 203 provides information to the control unit on the throttle angle. The transmitter has two contact positions, i.e. 0° (idling speed) and greater than 720 throttle angles.
Temperature transmitter 202 is of Negative Temperature Coefficient (NTC) type and provides continuous information to the control unit on the engine temperature. In the event of loss of this signal, the control unit will simulate, by default, an engine temperature of +45°C.
Air mass meter 205 is built into a plastic housing. In the event of a loss of signal from the air mass meter, e.g. if the filament should fail, an emergency system known as the "Limp-home" function in the control unit will come into operation. The car can then be driven, although its driveability will be limited. When the "Limp-home" function is operative, warning lamp 47P, CHECK ENGINE, will light up. It is located in the combined instrument, and is supplied from fuse 7. (The lamp can also be energized from EZK-type ignition systems.)
Fuel is supplied to the engine by electrically driven fuel pump 103 and feed pump 101, or fuel pump 323 with integrated feed pump, which draws fuel from the fuel tank and pressurizes the fuel in the system.
The control unit is connected to the air-conditioning system via pin 14, "AC 156". NOTE: Pin 14 of control unit 200 is connected to pin 87B of AC time-delay relay 156, via cable 544.
When the AC compressor is running, the control unit will compensate for the increased load applied by the compressor at engine idling speed. A signal (earth) is applied from pin 3 at full throttle, which disconnects the AC compressor.
Test connector 204 should be used for all fault tracing. When pin 1 in the socket is earthed, flashing codes will be obtained on the CHECK ENGINE lamp.
Two-pole auto./man. connector 322 must be fitted with a jumper between terminals 1 and 2 if a cold-start valve is subsequently fitted. Control unit 200 is connected to EDU1/EDU2 trip computer 210.
Exhaust gas emission control, Lambda
The car is equipped with an adaptive Lambda system, which compensates for variations in the fuel/air mixture caused by changes in the fuel system.
Lambda sensor 136 continually measures the oxygen content of the exhaust gases, thus enabling the control unit to adjust the mixture to as close to Lambda = 1 as possible. The sensor is heated by preheater 271 (protected by fuse 285 in the wiring).
Automatic transmission
Cars with automatic transmission are also equipped with switch 76 which will close when the selector lever is set to "Drive", and the control unit will then compensate for the increased load applied by the automatic transmission when the engine is running at idling speed. Three-pole auto./man. connector 322 for automatic transmission has a plug which distinguishes it from the version for manual gearbox.
Fault-tracing hints
Always bear in mind the following when carrying out fault-tracing in the wiring
1. Always disconnect the 35-pole/25-pole connector from the control unit and the connector on the air mass meter. NOTE: These two components can easily be seriously damaged if measurements are carried out at their terminal pins.
2. Always disconnect the electrical connection from the component which is suspected of being faulty.
3. Use an ohmmeter (not a buzzer) to carry out check measurements in the wiring.
Before carrying out fault-tracing in the wiring, check fuse 13 and check that the supply to it is live. Check also fuse 285 for the Lambda sensor preheater, if fitted.
The common earthing point (201) for the system is important for correct performance of the system. The location and connection must not be changed. The performance of the system may be disturbed if the location is altered, e.g. during other work on the engine.