PeachParts Mercedes-Benz Forum - View Single Post - What in the world is wrong with my '94 C280?

brookspw · #4 08-08-2009, 08:44 PM

Update on my surging idle issue.

It runs smoothly now...some of the time. It seems to be smoother when cold than hot, but is intermittent in both.

Thanks to Arthur Dalton's help I have eliminated the purge/regen valve as the culprit. It is definitely clicking now to open/close the valve. Frankly...I never heard it before, but I do now. Maybe it was stuck closed or not closing all the way and it was yet another problem. But...I still have the idle surge part of the time.

His next suggestion was to see if I have an internal leak in the fuel pressure regulator diaphragm, which I'll check tomorrow.

I removed the air flow meter, checked that intake flex tube it is attached to, rubbed wd40 on the seals and internal ends of the tube just to make sure no external air is getting in. This is a new air flow meter, by the way.

I get horrible gas mileage from it running rich when surging...maybe I have excess fuel leaking from the regulator diaphragm...we'll see.