Thanks for the insight 97.

I think what Mercedes is trying to do is allow blower pressure to overcome any vacuum to the flow valve. It is also a PWM signal to the Change-Over valve that is designed to fail shut with or without power.

It is operated by the ECU pulsing the Change-Over valve so the vacuum signal can be adjusted to regulate the AIR flow into the exhaust ports and then down stream.

The faster the C/O valve is pulsed the stronger the vacuum signal is and the more the flow valve opens....just like some of those domestic EGR valves on Chebbies and such.

The only time this valve passes a vacuum signal is as it opens ...allowing just a small volume of vacuum to pass.....it appears the flow valve will never see a full intake manifold vacuum of 17 inches.

Maybe the O2 signal is referenced in the ECU, and as O2 signal drops the PWM signal also drops, reducing AIR flow. i am now wondering if there is a chain of reference to the CTS.

I have not found any explanation of the 'Logic Chain' for this system. I wonder if Beckmann technologies has any insight to offer.


regards

dk


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