How to adjust Idle speed - 86 300e
 

How do I adjust idle speed on a 300e? I have looked at the cd and I can not find the info on my engine: 103.983 Is there a mechanical adjustment on this engine. Should the idle be at 750 rpm's +/- 50? It is an auto trans.

Larry:

Idle speed is set electronically on these engines and isn't adjustable. Should be 750 rpm or so in neutral, 500 rpm in gear when warm, higher when cold.

If it varies, car dies sometimes when coming to a stop, or idles rough, check the idle valve -- there are a large number of posts concerning idle problems on these cars!

Erratic idle is a sign of a vacuum leak, and in spite of all the electronic fuel injection and mixture control, vacuum leaks still can cause funny idle -- check all the rubber hose ends, etc!

Peter

Thanks for reply
 

I appreciate your reply. I took off the air filter to take a look see and then decided to see if anyone had responded. I am glad I did not go any further. Thanks.

Larry:

Is this car new to you? If so, I'd check to see that the air filter housing mounts were good (mine were broken!). They are little rubber gizmos that have a bolt on both ends -- one goes to the nut holding the bottom half of the housing in place and the other into the head or intake. If they are broken, you can get dirt in the intake -- read worn out motor!

All the rubber parts in the engine compartment will die on these cars with heat and age -- I've replaced all the rubber connectors on the various vacuum and manifold pressure signal lines, and the idle valve hoses. Makes a huge difference!

Peter