Warm up the engine. The engine can be considered warmed up when the lower radiator hose becomes warm. The minimum oil temperature is +60°C for a carburetor engine, +80°C for an engine with a fuel injection system.
Turn off the air conditioner.
- VEZ: The knock sensor is OK, but the engine electronics indicator lamp does not show any fault signals.
- VEZ for 83/85 kW engines: throttle position sensor switch (cold running contacts) included.
Note: The idle and knock sensor contacts affect the ignition timing. If the knock sensor is not working, the ignition timing will shift later by 10° in a later direction after each revving.
Connect the tachometer and stroboscope according to the instructions.
Note: The vacuum diaphragm regulator is removed or remains connected depending on the model, see the ignition timing table.
Start the engine and let it idle.
Engine NQ up to 7.88: insert a replacement fuse into the fuel pump relay and check the ignition timing no earlier than after 4 seconds.
NG engine with 8.88: connect a control voltmeter, for example M.F.P-1527, to diagnostic connectors "A" and "B" as shown in the figure. The diagnostic connector is located in a recess under the shelf in the driver's side footwell.
Connect plugs "C" and "D" and leave them connected throughout the test.
Attention: Already 4 seconds after connecting the plugs, the VEZ control device sets a constant ignition timing for testing.
Illuminate the window in the clutch housing with a strobe light.
Caution: There is a danger from rotating pulleys and V-belt.
The ignition is adjusted correctly if the ignition timing mark appears to be stationary below the pointer.
If the ignition marks do not match, loosen the distributor clamp bolt and turn it until the marks match. To turn the distributor, you can lightly tap the screwdriver handle in the direction of rotation.
Tighten the bolt to 25 Nm.
NG engine up to 7.88: remove the fuse on the fuel pump relay.
NG engine from 8.88: Disconnect plugs "C" and "D". Briefly increase the engine speed above 2500 rpm, then let it idle. The ignition timing should now fluctuate between 7° and 20° before TDC.
Check the idle speed setting.
Check the ignition timing again.
Remove measuring instruments.
If removed, install the vacuum line onto the distributor or control unit.