Ford Sierra - Engine idle speed check

Caution: Before carrying out any carburettor adjustments, ensure that the ignition timing and spark plug gaps are set as specified. To carry out the adjustments an accurate tachometer and an exhaust gas analyser (CO meter) will be required.

Ford VV carburettor

1 Ensure that the air cleaner is correctly fitted, and that all vacuum hoses and pipes are securely connected and free from restrictions, then run the engine until it is at normal operating temperature.
2 Stop the engine, and connect a tachometer and an exhaust gas analyser in accordance with the manufacturer�s instructions.
3 Start the engine and run it at 3000 rpm for 30 seconds, ensuring that all electrical loads are switched off (headlamps, heater blower etc), then allow the engine to idle and check the idle speed and CO content. Note that the CO reading will initially rise, then fall and finally stabilise after between 5 and 25 seconds.
adjustment screw locations - A Idle speed screw B Idle mixture screw 4 If necessary, adjust the idle speed screw to give the specified idle speed (see illustration).
5 Checking and adjustment should be completed within 30 seconds of the meter readings stabilising. If this has not been possible, repeat paragraphs 3 and 4, ignoring the reference to starting the engine.

Weber 2V carburettor

Models without stepper motor
6 Proceed as described for the Ford VV carburettor but note the following:
Weber 2V carburettor adjustment screw locations - 2.0 litre models up to 1985 A Idle speed screw B Idle mixture screw 7 It is permissible to loosen the air cleaner securing screws to allow easier access to the carburettor adjustment screws but ensure that all vacuum hoses and pipes are securely connected. For adjustment screw location see illustrations. Weber 2V carburettor adjustment screw locations - 1.6 litre models A Idle mixture screw B Idle speed screw

Models with stepper motor (ESC II system)
8 The idle speed is controlled by the ESC II module via the stepper motor. The only idle speed adjustment possible is provided by the �idle speed adjustment� wire, which can be earthed to raise the idle speed by 75 rpm. No other method of idle speed adjustment should be attempted. If the idle speed is incorrect, the problem should be referred to a Ford dealer, as the problem probably lies in the ESC II module for which special diagnostic equipment is required.

Pierburg 2V carburettor

adjustment screw locations A Idle speed screw B Idle mixture screw 9 Proceed as described for the Ford VV carburettor. For adjustment screw location (see illustration).

Weber 2V TLD carburettor

10 Proceed as described for the Ford VV carburettor, noting the following points:
adjustment screw locations A Idle mixture screw B Idle speed screw 11 Ensure that the vacuum pipe and the camshaft cover breather hose are securely connected to the air cleaner and are free from restrictions.
12 When warming-up the engine, run the engine until the cooling fan cuts in.
13 For adjustment screw location (see illustration).

Fuel injection

2.0 litre SOHC models
14 Idle speed is controlled by the EEC IV module and the only means of adjustment provided is by the yellow �idle speed adjustment� wire which allows the idle speed to be raised by 75 rpm.

2.0 litre DOHC models
15 Idle speed is controlled by the EEC IV module, and manual adjustment is not possible.
16 The �base� idle speed can be adjusted, but only by a Ford dealer, using special equipment.

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