Volkswagen Golf/Jetta 2 manual

Idle speed - adjustment
Fuel and exhaust systems - K-Jetronic fuel injection - 8 valve engines / Idle speed - adjustment

1 Run the engine until the oil temperature is at least 80°C. Do not let the engine coolant temperature rise above normal as the electric radiator fan will run and this should not be operating when checking or adjusting idle speed.

2 Check the ignition timing and adjust if necessary.

3 Except on air conditioned models, the main headlights should be turned on. Disconnect and plug the crankcase breather hose from the valve cover.

4 Where air conditioning is fitted, the system must be switched off during checking and adjustment.

5 If the injector pipes have been reconnected just prior to checking the idle speed, run the engine up to 3000 rpm a few times and then let it idle for a minimum period of two minutes before checking the idle speed.

6 If adjustment to the idle speed is necessary, remove the locking cap from the adjustment screw on the throttle assembly and turn the screw to achieve the specified idle speed (see illustration). Adjustment should be made only when the radiator fan is stationary.

4.6 Idle speed adjustment screw location in throttle valve housing (arrowed)
4.6 Idle speed adjustment screw location in throttle valve housing (arrowed)

7 If an exhaust gas analyser is available, check the CO reading and compare it with the specified figure. If necessary adjust the idle mixture.

8 Air conditioned models will also be fitted with an increased idle speed valve and, in some instances, a second idle speed boost valve. To check these, refer to Sections 5 or 6, as applicable.

© 2019 All Rights Reserved.