hey guys. I know some of the W140 6cyl guys have been complaining of the bad idle. Well today I decided to work on the benz. I wanted to see what differen type of true cold air intake systems I could run. I took off the huge intake airbox/plenum and once I got it off I had a good look at everything.

I realized that the throttle cable was loose, very loose. I usually had to put the gas pedal in a about 2 inches before i got any responce. so i tightened it up by simple twisting the hex shaped screw with my fingers and went back in the car to check a few times until it was just right. now the throttle body opens up just a 1/4 inch past the closed pedal position which is exactly where i wanted it.

wow car behaves totally different. for starters, the car used to rev at like 500-600rpm which was low but i never figured out why, i just thought thats how it was. now it idles at a much more natural 700-800rpm. revs much more smoothly and it idles as a mercedes should, perfectly smooth. I still need to replace the motor mounts but this solve alot of the little annoyances the failed mounts produced.

Also i switch out my 20w-50 with some 5w-30. MAN what a change. car revs like a bat out of hell. So much better than with the 20w-50. I'm definately glad i made the change.

Lesson learned: keep tight throttle cables properly tight (remember don't over tighten though, just enough so gas pedal engages just as you push it).

hope that helps.

 

just to note - the V8s with electronic throttle - never never rev it from iside the engine bay - there are two sensors on the throttle, one by the foot, one in the engine bay. if the two get 'out of sync' it upsets the computer


but thats V8s...

 

6 cyl is definately alot more simple than that. also i shoudl note mine is a OBD1 300SE so its doesn't have nearly as complex a computer system. the upside to that, modifications REALLY make a difference.