Note: The engine must be warmed up to normal operating temperature, with the ignition timing set correctly and the valve clearances adjusted (where they are regulated). The air filter should be in good condition and all electrical components (including air conditioning system where fitted) must be turned off.
1. Connect the tachometer and CO meter to the engine. Mechanics use a special CO tester, the probe of which is installed in the exhaust system pipeline, but you can use a regular tester that is inserted into the exhaust pipe. However, please note that on models with a catalytic converter on the exhaust pipe, correct CO readings cannot be obtained.
2. It is not possible to adjust the idle speed manually, since the idle speed stabilizing pneumatic valve is actuated by the electronic control unit. If, at normal engine operating temperature, the idle speed does not correspond to the values specified in Specifications values, check the air intake system for leaks and the operation of the stabilizing pneumatic valve (see Power and exhaust systems).
3. Check the CO meter readings against those given in Specifications values. If adjustment is required, remove the plug from the air flow meter and turn the adjusting screw until the desired value is obtained (some models may require a hex key). Finally, install the new protective plug.
Adjusting the CO level on the Motronic system.
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