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mark houghton mark houghton is offline
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Join Date: Jul 2008
Location: Central Washington State
Posts: 3,775
Originally Posted by JFairman View Post
Have you tried lowering boost control pressure with your Brian Leask adjustable warmup/control pressure regulator yet?
Great job describing how vaccum and boost leaks differ in their affect to mixtures in boosted applications. That's always a tough one to internalize.

But you lost me in your final comment re: lowering the boost control pressure. Are you referring to that as a possible cause of rich idle?
It's been my understanding (fact or fiction?) that the WUR boost enrichment is fully in by around .3 bar or so. Correct? So even though at idle where there isn't enough boost to register on the gauge, we will still see some level of enrichment occuring via the boost signal at the WUR? And if you were to lower the boost CP at the WUR, then affectively you would get even more fuel vs. air at these very low idle boost conditions due to the lowered fuel pressure resistance at the control arm? So, if a surging idle is the result of being too rich as a result of the WUR's boost circuit, wouldn't he want to try increasing the boost CP to lean out the mix?

I must be missing something in the translation. You da man with all that German- Beemer experience.
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.

Last edited by mark houghton; 10-23-2009 at 01:56 PM..
Old 10-23-2009, 01:21 PM
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