I have been running down a sluggishly accelerating '91 300CE with the M104 engine. Recently, gas mileage has suffered as well, down maybe 4-5 mpg...although part of that may have been due to a plugged fuel filter - which has been changed.

Car still seems to have a "dead" spot when I hit the gas pedal, and I'm beginning to think - after reading thru a bunch of old posts - that I may have a timing advance issue. I have located 2 vacuum pods behind the windshield washer bottle on the passenger fender wall. One runs to the air pump...

Can someone explain what these do and how to test them??

Thanks, ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE