BenzWorld Junior Member
Date registered: Jul 2005
Vehicle: '95 E420
Location: Southern California Desert
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1995 E420 engine surge
I've search the forums for quite a while with no success so here goes:
I have a 1995 E420 that I got about two years ago. Mileage is about 155,000. It has developed a problem this winter:
Most days, in the morning, it begins to surge while idling a stoplights.
Surges strongly when in Drive, smooths out if I put it in neutral.
Sometimes I can feel it surging even as I accelerate from a stop. It sort of jumps forward a few times while the car speeds up.
It only surges after the engine warms up.
It is worse in cold weather.
Sometimes the red ASR light comes on, the idle jumps up, and it goes into limp mode and I have to restart the car to clear the light. The ASR light only (that I recall) comes on when it's cold out, when I let off the gas or am setting at a stop light.
Sometimes it will be just fine for a day.
The EGR valve checks out okay.
It seems to have all its horsepower.
I disconnected the MAF for a while with no change in symptoms other than the gas mileage dropped from 22mpg to 15.
I have not replaced plugs and wiring or rotor caps.
I looked for vacuum leaks and found one on the EGR, but it didn't help.
I took it to two different mechanics. One kept it three weeks, couldn't figure it out, and wanted to charge me a lot of money to tell me that he guessed it might be this or that. The other admitted that he couldn't figure it out, charged me a half hour labor and suggested I take it to a dealer.
Both checked the codes and found nothing related to the problem.
Any suggestions? It's a blast to drive when it's running well.