Adjusting idle speed and CO content in exhaust gases (Mercedes-Benz S-Class W116)

When performing this work, it is necessary to take into account that it can be performed qualitatively only with the availability of special tools and devices. In their absence, only the idle speed can be adjusted. To adjust the CO content and subsequent sealing of the adjustment screws, it is necessary to contact a service station.

Adjust the ignition timing.

Check the air supply system.

Warm up the engine to +60°C. Do not adjust the idle speed on a hot engine after intensive driving.

Disconnect the fuel supply drive rods.

Check the ease of opening of the throttles.

Turn on all on-board electrical system consumers and check engine operation.

After following these recommendations, you can adjust the idle speed in the following sequence:

Install the fuel supply drive rods, making sure that the rocker arm roller rests on the stop without force and that the control rod is fully extended in vehicles with an automatic transmission; adjust if necessary.

Idle speed screw (see arrow in Fig. 149) adjust the rotation speed within 750...850 rpm.



Check the CO content in the exhaust gases and, if necessary, the screw on the control device (see arrow in Fig. 150) adjust within 3.5% CO. When turning the screw to the left, the mixture becomes leaner, to the right, it becomes richer. Access to the control device is possible after removing the body trim.





Check the idle speed again and adjust if necessary.

Check the stops under full load with the engine off, as for carbureted engines (see fig. 128).

Article was borrowed from the website MERCEDESMAN.ru