Memory damage
1. The Mono-Jetronic system is equipped with a fault memory for reading encoded data. In the event of damage, a warning lamp is displayed on the instrument panel.
2. If the engine does not start from the starter within six seconds, leave the ignition on. If the engine starts, set to idle
3. Connect a good fuse across the contacts of the fuel pump relay under test for at least five seconds.
4. Remove the fuse, then count the number of illuminated pulses given by the warning lamp. If no damage is found, code 4444 will be issued (four groups of four flashes).
5. Clear the code, then repeat the test by connecting and disconnecting the fuse until code 0000 appears, indicating the end of the test.
6. Decoding of codes is given in the following table:
- 1111 Control unit
- 1232 Throttle positioner
- 2121 Throttle switch
- 2122 Speed sensor
- 2212 Throttle Potentiometer
- 2312 coolant temperature sensor
- 2322 Intake air temperature sensor
- 2341 Lambda control
- 2342 Lambda sensor
- 2343 Limit adjustment block composition of the mixture, lean
- 4431 Same as 1232
7. To clear codes 2341 and 2343, disconnect the control unit wiring for at least thirty seconds with the ignition off.
8. To reset the fault memory, turn off the ignition, then connect the fuse across the fuel pump relay. Turn the ignition on, wait at least five seconds, then remove the fuse.
Note: Models from 1989 are described in Section 4, Chapter 10.
Idle speed switch/control valve
9. Turn on the ignition, then open and close the throttle. The control valve should operate twice. If not, disconnect the wiring and connect a diode test lamp across the connector pins. When the throttle is closed, the control lamp will light up, when the throttle is open, it will go out.
10. Start the engine at idle speed, then disconnect the wiring and reconnect it. The engine speed should increase, then decrease. If not, replace the control valve.
11. Turn off the ignition, then disconnect the wiring from the throttle positioner.
12. Connect the battery voltage and ground wire to the positioner clamps until the plunger is fully moved 2.5 cm, then remove the wires.
13. Press the plunger to the limiter, then using a feeler gauge, check the gap indicated in fig. 3.34, it should be equal to 0.5 mm. Adjust the screw nut if necessary.
14. Connect an ohmmeter as shown. With the probe correctly positioned, the switch should be open; with the probe removed, the switch should be closed (0 ohm).
Throttle positioner
15. With the ignition off, disconnect the wiring from the throttle positioner.
16. Guided by fig. 3.35 and using an ohmmeter, check the resistance data.
Throttle Potentiometer
17. Disconnect the wire contact from the potentiometer.
18. Guided by fig. 3.35 and using an ohmmeter, check the resistance data. When tested between terminals 1 and 2, the resistance will change during the first quarter of the throttle opening, then remain constant. Between terminals 1 and 4, the resistance will be constant during the first quarter of the throttle opening, then it will change.
Injector
19. Start the engine and warm up to operating temperature, then remove the air filter.
20. With the engine idling, check that the 'cone' of the aerosol injected onto the throttle is even. Increase the engine speed to 3000 rpm, then quickly close the throttle. The injector should briefly close, indicating that the engine braking system is functioning properly.
21. With the ignition off, check that the injector does not pass more than two drops per minute.
22. Remove the inlet elbow from the pump section.
23. Turn on the starter and check that the nozzle is visible on the throttle. If not, disconnect the injector wiring and use an ohmmeter to check that the injector resistance is 1.2-1.6 ohms at an ambient temperature of 15-30°C.
24. Connect a diode control lamp to the central clamp, then turn on the starter. The control lamp should flicker, indicating the presence of current to the injector.
Throttle damper (models with manual transmission)
25. Check that when the throttle is closed, the lever leads the plunger into the shock absorber by at least 4.0 mm. If not, loosen the mounting nut and adjust the damper so that the arm just touches the plunger From this position, rotate the damper 4 and 1/4 turns towards the arm, then tighten the nut.
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