Checking idle speed and CO level on vehicles with catalytic converter

Engine Type M 44.43/44 Note

Idle and CO level adjustment is no longer possible on vehicles fitted with catalytic converter. When checking the idle CO level, the oxygen sensor is not disconnected.

Check requirements

Perfect condition of the mechanical engine components. Loads must be turned off while checks are made. Perform checks as rapidly as possible to avoid excessive heat buildup in the inlet ducts as this would give faulty CO level readings. Ambient temperature 15-35 deg. C.

1. Connect commercially available exhaust gas adapter to test connector of catalytic converter.

2. Warm up engine to operating temperature. (Oil temperature 70 to 90°C), check with oil temperature tester (Special Tool 9122 and 9122/2).

3. Do not disconnect oygen sensor connector. Connect CO level measuring instrument and separate tachometer according to manufacturer's instructions.

Idle speed:

Engine Type M 44.43 840 ± 40 rpm Engine Type M 44.44 880 ± 40 rpm


Checking idle speed and CO level on vehicles with catalytic converter Printed In Germany - II, 1991

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