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IMONBOOST IMONBOOST is offline
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Join Date: Apr 2001
Location: San Juan, Puerto Rico
Posts: 373
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911st, I think we are very much in synch, although I never thought of the spring under the plunger option and replace the WUR with an injector to manipulate the control pressure, I think the theory on this one is very clear and doable. We just have to make sure the plunger does not stay open when the car is shutdown. But this can be achieved pretty easily letting the pump run for a few seconds after shutdown to build up pressure that will overcome the spring. I have a 911 Carrera 3.0 I can use as the guinea pig before plunging into the turbo 3.6.

On the other hand, I need more details on the inner workings of the FD. I am craving CIS K-Jetronic info and have been reading all over the internet. I am gonna try and get a CIS system from a Junkyard for experimenting.

Back to your spring under the plunger idea, this does achieve getting rid of the metering plate and have a single point of control, the big fuel injector which combined with an ECU and the other signals (TPS, MAP, etc) should do the trick.

Update: http://www.porsche928forums.com/download/manuals/CISRebuild.pdf, all credit to it's author Richard Andrade. This certainly confirms your concerns on controlling fuel with simple plumbing and pressure, the FD is a little monster. I have yet to understand the function of the diaphragm and springs for every injection port. I will figure it out, unless someone already knows the answer and chimes in before I do :-).
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Last edited by IMONBOOST; 09-16-2010 at 07:55 PM..
Old 09-16-2010, 07:28 PM
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