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patkeefe patkeefe is offline
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Join Date: Apr 2004
Location: Ringwood, NJ
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Alan:
This is the root of the problem. My Leask solenoid valve holds off any supplemental dropping of the control pressure to 4800 RPM, so I should get no enrichment at all from this. I have disconnected the boost signal line entirely from the WUR, and I still get the enrichment problem below 4000 RPM. The enrichment happens for no apparent reason.

My theory that I need to examine is that when I get to boost threshhold, the additional mass of air throws the airplate open, thus enriching the mixture. As I do not have a 930 fuel head or metering plate available to me for a comparison, I am guessing the inertial effects from the additional pressurized air blasts the airflow metering plate open further than it should, resulting in additional enrichment. I am thinking about putting an extra weight on the airflow plate as an additional counterbalance, with this weight being in the form of a large fender washer under the 6mm bolt which holds the actual plate to the pivoting arm. Not very scientific, but I am sort of clutching at straws.

I also need to check again for any air leaks. I have had some before, which gave me threshhold problems.

Pat
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Patrick E. Keefe
78 SC
92 968 Cab
01 Boxster
RIP, Early_S_Man & RoninLB
Old 06-19-2008, 03:00 PM
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