Contents: Removal and installation the… ↳ Idle speed adjustment ↳ Fuel pump ↳ Fuel pressure regulator ↳ Working nozzles ↳ Adjustment data ↳
Adjusting the mixture composition of the Bosch L-Jetronic fuel injection device
The ONS 2.0 dm³ NRB engines are equipped with a Bosch L-Jetronic multi-point fuel injection system. It ensures constant injection pressure, while the fuel dose is regulated by the opening time of the electronically controlled injectors. During engine braking, the fuel dosing is automatically switched off.
Removal and installation the throttle valve contactor
1. Disconnect the ground wire from the battery.
2. Disconnect the throttle contactor electrical wire connector, being careful not to damage the spring clip.
3. Remove the throttle contactor.
4. When installing, correctly position the contactor relative to the flat part of the throttle valve axis.
5. Install the washers and contactor mounting bolts and tighten them.
6. Connect the throttle contactor electrical wire connector and the ground wire to the battery.
Idle speed adjustment
1. Warm up the engine to normal operating temperature.
2. Connect the tachometer and exhaust gas analyzer.
3. Increase engine speed to 3000 rpm, hold it for 15 seconds and release the accelerator pedal, leaving the engine idling.
4. After the instrument readings have stabilized, read the idle speed and the CO content in the exhaust gases.
5. If necessary, adjust the CO content by turning the idle mixture adjustment bolt (see Fig. Adjusting the mixture composition of the Bosch L-Jetronic fuel injection device) after removing the seal from the flow meter.
6. Install a seal on the idle mixture adjustment bolt.
Caution! The idle speed is controlled by the EEC IV electronic control unit and a stepper motor that changes the throttle position accordingly. The idle speed cannot be adjusted manually.
Fuel pump
Vane roller pump driven by an electric motor. Brand: Bosch.
Compression pressure: above 500 kPa at 12 V and closed fuel drain.
Fuel pressure regulator
Brand: Bosch. Adjustable pressure: 250 kPa.
Working nozzles
The injectors are controlled electrically. Brand and type: Bosch 85 TF-9 F 593-AB.
Adjustment data
Idle speed: 850 rpm.
CO content: 0.5–1.0%