My '97 E300D surges and the tachometer ossilates up and down. I cleaned the resonance flaps with carb. cleaner normally used for a gas engine. Hope that was ok. Anyway, the resonance flaps are clean and problem persists.

Next, I disconnected the vacuum to the EGR valve to disable the valve. The car ran GREAT.

But with the EGR valve disabled, I noticed that the computer tells one of the resonance flappers (the one located between the EGR valve and the inlet air filter) to default to wide open and the check engine light comes on.

I checked the operation of the EGR valve with a vacuum pump. The valve works fine. Maybe it's the EGR sender?

Any thoughts?

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

Resonance flaps get 99% probability. Been there, done that. Cleaning will do very little.

Good luck,

Thank you Larry for sharing your experience. I will replace the resonance flappers if the problem persists.

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

There also is a resistor install in the map sensor that'll fix em.



Joe

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Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364