Audi A4 B7 (2005 - 2008) - 07 2.0 EGR Valves

Honest John Back Room » Technical matters
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Sat 11 Jul 2009 18:23
07 2.0 EGR Valves - Roly93
When do EGR valves open and close exactly ?

ie when is the exhaust gas allowed to recirculate through the engine and when does the valve close to allow turbo boost ?

I understoood that the EGR valve was open at idle or on the overun, is this correct ?
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Sun 12 Jul 2009 19:40
07 2.0 EGR Valves - IanW3
The EGR valve opens during light and moderate throttle cruising, to drop the combustion temperature. It is closed at idle to ensure closest control of mixture, and closed at full throttle to give maximum power. Since there is no fuel being injected on the over-run, it doesn't matter whether the valve is open or closed, but I imagine it would be closed.

A separate valve is used to control turbo boost - the wastegate.

Ian.
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