Note. The engine must be warmed up to normal operating temperature, with the correct ignition timing and adjusted valve clearances (where they are regulated). The air filter must be in good condition and all electrical components (including air conditioning system, where available) 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 pipe, but you can use a regular tester that is inserted into the exhaust pipe. Note, however, that on models with a catalytic converter in the exhaust pipe, a correct CO reading cannot be obtained.
2. It is not possible to manually adjust the idle speed, since the idle air stabilization valve is actuated by the electronic control unit. If, at normal engine operating temperature, the idle speed is not as specified in Specifications values, check the air intake system for leaks, as well as the operation of the stabilizing air valve (see Power and exhaust systems).
3. Check the readings of the CO meter with 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 wrench). Finally, install a new protective plug.
CO level adjustment on the Motronic system.
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