Quote:
Originally Posted by DieselAddict
No, they're all controlled independently. I don't quite understand the theory of why the 2 intake flaps work but I know they're for optimizing the engine's power band and maybe also idle quality. From my observation the one in the crossover pipe starts to move and restrict air flow around 3000 RPM. The one in the intake manifold opens just over 1000 RPM. The EGR flap opens around 2000 RPM at light throttle and closes with higher RPM's and/or full throttle.
One other thing I recently did with the flap in my crossover pipe is loosen the blade and re-adjust it, then lube it again. I also re-lubed the others. It seems to have helped some more. I still get the occasional ping but you really have to listen for it and it's much better than it used to be. I'm sure higher-cetane fuel would help further. The cetane additive I use can only do so much.
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I also own a 96 e300 d, and the following information pertains to my model too.
This information was provided in another thread, and the owner had a 95 E300d
Here's how the resonance flaps work on my car;
The valve in the crossover pipe, I'll call X/O, and the valve in the manifold itself, I'll call 3/6.
The solenoid for the X/O valve is connected to the Yellow / Brown wire pair, and is the upper of the two solenoids when in the as installed position.
The solenoid for the 3/6 valve is connected to the Grey / Brown wire pair.
In the relaxed position with no vacuum, the X/O valve is closed - i.e. the crossover pipes remain independent for their full length.
With no vacuum, the 3/6 valve is closed, and the manifold behaves as an independent pair of 3 cylinder manifolds.
<2400 rpm 3/6 valve Closed, X/O valve Closed
>2400 rpm &
<3500 rpm 3/6 valve Closed, X/O valve Open
>3500 rpm 3/6 valve Open, X/O valve Open