M1B Adjusting the Idling Speed (With Catalytic Converter)

M1B Adjusting the idling speed (cars with catalytic converter)

(For cars with the LH 2.2 fuel injection system.)

Tools:
- TSI tachometer
- Nut driver for the butterfly adjusting screw lock- nut, 83 94 322
- Jumper lead with switch 83 93 886




1 Remove the induction hose from the throttle body.

Open the throttle butterfly fully and wash the inside of the throttle body round the butterfly, using a cloth soaked in benzine or the equivalent.

2 Start the engine and warm it up.

Note: It is extremely important for the gearbox oil to be at normal operating temperature.

3 Undo the locknut on the throttle and lower the dashpot clear of the throttle lever.




4 Unplug the throttle position sensor connector and connect a jumper lead across pins 1 and 2 at the rear of the connector. (This sends a signal to the LH control module corresponding to closed contacts for the idling position, which is necessary for obtaining an accurate setting when carrying out adjustment.)




5 Undo the two throttle position sensor retaining screws and rotate the sensor clear of the throttle butterfly.

Also make sure that the throttle cable does not interfere with the movement of the throttle butterfly (cable slack).




6 Start the engine and disconnect current consuming items like the AC, headlamps, seat heating elements, etc.

Note also that adjustment must not be carried out when the radiator tan is running.

7 Connect the jumper lead with switch (83 93 886) to the single-pole test socket located adjacent to the right-hand wheel arch (green/red lead).

Cars not fitted with adjusting screw (air bleed screw):




8 Undo the locknut on the throttle butterfly adjusting screw, using nut driver 83 94 322, and turn the adjusting screw until the butterfly is fully closed.

Set the switch to "ON" (the IAC valve closes).

Adjust idling speed to 775 + 25 rpm and then secure the adjusting screw in this position by means of the locknut.

9 Set the switch to "OFF".

Check that engine speed changes and when stabilized settles down to a steady idling speed of 850 + 75 rpm.

Cars fitted with an adjusting screw (air bleed screw):




Turn the adjusting screw clockwise until it reaches the stop (fully seated) and tighten ft by means of the locknut.

Then continue adjustment as described in point 8.




10 Switch off the engine.

11 Adjust the throttle position sensor to the correct setting (closed in idling position).

Check that the sensor makes a clicking sound when the butterfly lever is moved away from the idling position. Do not confuse this sound with the click produced by the shift- up switch.

12 Adjust the throttle dashpot so that it closes within a period of 2-3 seconds.

Tighten the locknut.

13 Remove the jumper lead from the throttle position sensor connector and connect it to the sensor.