Idle Adjustment
 

W126

Would anyone be able to advise how one would adjust the idle on a 560SEL? I have seen my mechanic insert a rather long screwdrive into a hole on the top of the air breather to make this adjustment.

I wanted to clarify whether this was common practice before attempting to do it myself.

Many thanks.

There is no idle adjustment. It is all electronically controlled. You are talking about the mixture adjustment.

What is the idle doing that makes you want to adjust it?

Idle Adjustment
 

Thank you for your response Mr. Talylor. After the initial adjustment was made by the mechanic, it seems to run rougher than it did before. Not lumpy, but certainly not as smooth, perhaps a slight hesitation at times. Would this indicate that it has been adjusted too lean?

Thank you in advance for your assistance.

It's really hard to tell from here.

There are a variety of problems that can cause a rough idle - vacuum leaks, weak injectors, worn out O2 sensor, leaking air hoses, usw. In some of these cases, adjusting the mixture to spec will make the problem worse.

You need to take the car back to the mechanic, explain what is happening, and let him fix the problem. If he is unsure of what to test, find a mechanic with experience with your engine.

You could also go to Sears, buy a DMM with a duty cycle setting, get a 3 mm hex wrench, read the posts on how to do it, and try setting the mixture yourself. But a lot of folks have come to grief doing this.

Generally the mixture adjustment is sort of the crowning touch on a system that has its pieces working well - it is NOT a fix or compensation for other problems.

BTW - Is it a 380 or a 560?