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Thierry25 Thierry25 is offline
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Join Date: Feb 2009
Location: FRANCE (Besançon)
Posts: 310
Originally Posted by psalt View Post
It's a '79 so no Lambda. Any suggested changes to the test method? Which chart are you talking about?

Dr J,

There is more to fuel delivery at the injectors than height of the plunger. There is a differential pressure valve after the plunger slit and before the injector line. If your test method plumbing effects the pressure in the lower chamber, the amount of fuel at the injector will be different. My point about CIS lambda is that it controls the amount of fuel at the injector by varying this pressure with the FV pulses. The range of the delivery amount is quite large. If the lower chamber pressure is higher in your test than under running conditions, delivery at the injector will be lower. Have you tried the test with all the fuel lines hooked up normally and no test valve ?
Just my simple opinion

Actually, when the FV valve is triggered (50 to 75%) , it takes about 150 to 250 ml of fuel flow back to the tank ... this flowed fuel volume is no more availabe for the injectors !!!

So you reduce the upper valve restriction (différential pressure) .... but finally you draw more fuel back to the tank.

If the max injectors fuel flow is limited by the fuel pump flow rate capability.....

- you gain nothing by acting the FV on the max injector flows ( at fully metering plate deviation) .

- you gain nothing by increasing the system pressure.
965 C2T / 1991 3.3 TURBO
Old 01-20-2010, 01:02 PM
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