Technical characteristics of the fuel injection system «LE-Jetronic» (Opel Kadett E)

The 18E engine uses an intermittent fuel injection system "LE-Jetronic" bosch company with electronic control.

The principle of operation of the fuel injection system

The electric fuel pump takes fuel from the tank and delivers it under pressure of about 2.5 kg/cm² through a fine filter to the distribution line, connected by hoses to each engine cylinder. Installed at the end of the distribution line, the fuel pressure regulator maintains constant injection pressure and drains excess fuel into the tank, i.e. it ensures fuel circulation in the system and eliminates the formation of fuel vapors in it.

The amount of fuel injected is determined by the electronic control unit depending on the volume and temperature of the incoming air, the crankshaft speed and engine load, and the coolant temperature. The main parameter determining the fuel dosage is the volume of air intake measured by the air flow meter. The incoming air flow deflects the pressure flap, overcoming the spring force, and shifts it to a certain angle, which is converted into electrical voltage by means of a potentiometer. The corresponding electrical signal is transmitted to the control unit, which determines the required amount of fuel at a given moment of engine operation and sends pulses of fuel supply time to the electromagnetic valves of the injectors. Regardless of the position of the intake valves, the injectors simultaneously inject fuel twice per each revolution of the camshaft. If the intake valve is closed, the fuel collects in the space in front of the valve and is sucked into the cylinder the next time it opens, simultaneously with the air.



The additional air supply valve, installed in the air channel parallel to the throttle valve, supplies an additional amount of air to the engine during cold starting and warming up of the engine, which leads to an increase in the engine crankshaft speed at idle.

To facilitate starting a cold engine, an electromagnetic starting injector is provided, the opening duration of which changes depending on the temperature of the coolant by a thermal time relay.

Data for adjustment

Engine crankshaft speed at idle, rpm: 900-950.

Carbon monoxide (CO) content in exhaust gases, no more than, %: 0.5.

Fuel pump

The electric fuel pump is mounted on the right rear side member of the body.

Brand/Opel catalogue number: Bosch/90 136 950.

Fuel supply pressure, kg/cm²: 2.3-2.7.

Operating voltage, V: 7-15.

Pump performance at terminal voltage of 14 V, l/h: 60.

Fuel filter

Brand and type: Mann WK 613.

Air filter

Air filter with replaceable dry filter element.

Make and type: Mann C 2668 or GM 90 108 602.

Fuel pressure regulator

Regulating pressure, kg/cm²: 2.5.

Air flow meter

Brand and catalog number: Bosch 90 136 946.

Resistance when measured between terminals, Ohm:

• "8" and "9": 160-300;
• "7" and "5": 60-1000;
• terminal "8" of the block and terminal "8" of the meter: 0;
• terminal "9/3" of the meter and the block: 0;
• terminal "7" of the block and terminal "7" of the meter: 0;
• terminal "5/1" of the meter and output "5" of the block: 0.

Electronic control unit

Brand and catalog number: Bosch 90 122 322.

Resistance, Ohm:

• when measuring between plug "1" in the block connector and terminal "1" of the ignition coil: 0.
• when measuring between plug "5" in the unit connector and "ground": 0.

Throttle position sensor

The position type throttle position sensor is installed on the throttle. The signal from the sensor is used to determine the engine operating mode (idle or full load).

Brand and catalog number, Bosch 90 122 534.

Throttle switch resistance during continuity testing, Ohm:

in the "full load" position:

• between terminal "3" of the block and terminal "3" of the switch: 0
• between terminal "9/4" of the switch and terminal "3" of the block: 0.

in the "idle" position:

• between terminal "2" of the block and terminal "2" of the switch: 0;
• between terminal "9/4" of the switch and terminal "9" of the block: 0.

Coolant temperature sensor

Brand and catalog number: Bosch 90 080 939.

Resistance at coolant temperature, kOhm:

• 0°C: 4,8-6,6;
• +20°C: 2,2-2,8;
• +40°C: 1,0-1,4;
• +80°C: 0,23-0,27;
• +100°C: ~0,2.

Resistance when checking the integrity of the circuit, Ohm:

• between terminals "10" of the sensor and the block: 0;
• between terminal "33" and the "ground" plug of the electronic control unit: 0.

Additional air supply valve

Brand and catalog number: Bosch 90 136 928.

Valve resistance, Ohm: ~40-75.

Electromagnetic injection nozzles

Brand and catalog number: Bosch 90 128 848.

Resistance, Ohm:

• when measuring between plugs "12" and "5" in the control unit connector: 4;
• when measuring between plug "12" in the control unit connector and the injector: 15-19;
• when measuring between plug "9" in the control unit connector and terminal "8" of the control unit power relay: 15-19.

Fuel pump relay

Resistance between terminal "4" of the socket and terminal "50" of the relay, Ohm: 0.

Power relay

Resistance, Ohm:

• between terminal "9" of the block and terminal "87" of the relay: 0;
• between terminal "30" of the relay and the positive terminal of the battery: 0.