wheeler wrote: ↑30 Nov 2017, 01:17Everything I'm writing here is based on the RHZ & RHY engines.tmead wrote: ↑29 Nov 2017, 23:52 Yes, in theory the ecu could control the valve to hold it partially open against the return spring, but only if there was a feedback mechanism of some kind to provide a servo loop. Without this the system is not capable of securely and confidently adjusting to any particular position other than fully open or closed as EDC observed. The vnt turbo uses a similar or identical valve and has a feedback device which allows the ecu to adjust the vanes to any required position, which is a different control.
The air doseur's official name in the technical documentation is the EGR throttle butterfly. It's there to assist the EGR operation. It can be opened to any position between fully open & fully closed, it does this with calculated values from the ECU & doesn't need any feedback sensor. On these engines the EGR valve & turbo wastegate (RHZ only) Also work exactly the same, they are vaccum operated against a spring return, they can be opened to any position & neither have a direct feedback sensor either.
You can actually watch the valve operating when the engine is idling if you take the air pipe off.
Ok, so I bought a spare doeseur from ebay and connected the vacuum hose to it in place of my own one, I got someone to watch it as I revved the car from idle and it didn’t do anything, only when I turned the engine off did it flap closed for about 5 seconds before opening again.
I'm not saying that it doesn't do anything to help the EGR but maybe the EGR wasn't operating when I was testing it. I might repeat the test with a warm engine or something.
I'm really quite interested in this unit and would like to like to know more.