Mercedes-Benz Forum banner

1 - 6 of 6 Posts

·
Registered
'73 450SL, '83 300CD, '01 E320 4matic
Joined
·
2,446 Posts
Discussion Starter #1
Hello... my car is actually a 126-(300SE)..I think I may have posted here with this question before and not found an answer. You guys have all the I6's, so I thought maybe you guys would have some information, as most of the 126's are V8s.

I know my problem isn't unique, I have searched and found many people who have had this problem, but I have not found a good solution.

The car starts fine, and basically runs well. It gets good mileage and idles well in gear (and idles at the correct speed).

When you start the car, cold, it idles at around 750-800 RPMs, and idles fairly smoothly until it warms up. Once it's warm, the idle surges at a regular interval. It only does this in park or neutral. It seems to run fine under load (in gear). It probably oscillates between about 500-900 RPMs, back and forth.

I cannot find a source for this problem. I have actually removed every single vacuum line, and plugged the ports. I also put some small clamps around the ICV boots, thinking that was a source of a possible leak. No improvements. I have sprayed carb cleaner and starting fluid around the injectors. I also tried propane. No changes in the idle. I have cleaned the ICV. The ICV seems to work fine.

Every search I have done suggests injector seals being bad, and starting fluid and carb cleaner should indicate this as the problem. I can't find any vacuum leaks or any reason this problem should occur. It only occurs when the engine is warm, and the car is in park or neutral.

Any help would be greatly appreciated. Although it has no affect on the drivability or the economy of the car, it's driving me nuts and I would like to get it right.

Thanks-

Aaron
 

·
Registered
'73 450SL, '83 300CD, '01 E320 4matic
Joined
·
2,446 Posts
Discussion Starter #4
I have cleaned the throttle body (it wasnt really dirty). I will try cleaning the mass airflow sensor. Unplugging it seems to smooth the idle out considerably.

Is there a test for the OVP relay?
 

·
Registered
w126 300 se, w109 300 sel
Joined
·
6 Posts
Hello aaron did you sort the problem ? i ask because my 300se is having very similar problems .

Ralph
 

·
Registered
1982 300CD 1983 230E
Joined
·
110 Posts
Had a similar problem with my W124 300E. Revved between 0-1.5. I had my fuel system re-done and it fixed the problem. $150 at the most at a specialty shop.
 
1 - 6 of 6 Posts
Top