Electromagnetic idle speed controller
1 – coil winding, 2 – anchor, 3 – valve stem, 4 – valve seats
Air flow meter
1 – mixture quality adjustment screw, 2 – damper flap, 3 – damper chamber, 4 – electrical connector, 5 – air temperature sensor, 6 – measuring plate
Idle speed is set only by the EEC IV module and cannot be adjusted manually.
Engines with catalytic converter
On engines with a catalytic converter, the mixture quality is regulated by the EEC IV module and manual adjustment is not possible.
Engines without catalyst
Seal of the mixture quality adjustment screw
The screw seal is indicated by the arrow.
The air flow meter is upside down.
Adjusting the quality of the mixture
Before adjusting the quality of the mixture, it is necessary:
- check and, if necessary, adjust valve clearances;
- check the condition and replace the air filter if necessary;
- check the condition of the ignition system;
- warm up the engine to operating temperature.
1. Connect a tachometer (with the ignition off) and a gas analyzer to the engine.
2. Increase engine speed to 3000 rpm and hold it for 15 seconds, then return the engine to idle.
3. Take instrument readings.
4. If the CO content value deviates, remove the protective cap from the mixture quality screw, increase the engine speed to 3000 rpm and hold it for 30 seconds, then switch the engine to idle mode and, by turning the screw, set the required CO level.
5. On DOHC engines without a catalytic converter, remove the cover from the mixture quality adjustment potentiometer (located on the right in the engine compartment, behind the full pressure sensor) and turn the screw to obtain the required CO concentration. If the adjustment does not change the instrument readings, it is possible that the potentiometer is in the extreme position. To set it to the central position, turn the adjustment screw 20 turns clockwise, then 10 turns counterclockwise and repeat the adjustment.
6. On V6 engines, the front air flow meter should be adjusted first. The rear air flow meter should only be adjusted if the front air flow meter adjustment range is insufficient.
7. Turn the mixture adjustment screw with an Allen key until the desired CO level is reached.
8. Turn off the engine and disconnect the measuring instruments.