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Thierry25 Thierry25 is offline
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Join Date: Feb 2009
Location: FRANCE (Besanšon)
Posts: 310
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Originally Posted by Thierry25 View Post
here is the 2 nd measurement






However , the fuelling is not correct and it is too lean above 4800 rpm ( almost 13 ) . (We can noticed the AFR comes back to 12.5 while the boost decrease above 6000 RPM) .

As can be seen previously, the mixture was a bit too lean ( let's say 12.8) at high RPM under 1b of boost. Although the big decrease of the control pressure , the Kjet was not able to provide richer mixture.

Prior to do something else, I verified the fuel supply system.

As specified in the Porsche workshop manual:

- I controlled the fuel system pressure ....and measured 7 bars ( so I thought no problem on this)

- I verified the fuel flow : I've got about 1.7 liters/ 30 sec . Porsche recommend 1.5L/30sec at least. So the flow was in the tolerance...

- I verified the control pressure under warm condition : Measured 4.5 bar ....which is exactly the correct value. By this opportunity, I either tested the AIC +frequency valve working. The CP was decreased to 1.2 bar under 90% duty cycle.


At that time, Keith suggested to me to " play" with the lambda frequency valve instead to play my AIC frequency valve. According to him I could maybe get more fuel by playing. As described into the Porsche manual , the enrichment device ( which is under the driver seat) triggers the lambda frequency valve to stable 50% duty cycle while the throttle exceed 66░. It also increase this duty cycle to 75% during 0.5 second while the throttle moves from 0░ to 7░ and from 6░ to 66░...( This is for acceleration enrichment purpose only) . So I look into the Porsche diagram if it could be possible to get 75% enrichment all the time. Finally it was quite easy to do.
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965 C2T / 1991 3.3 TURBO
Old 06-29-2009, 11:04 AM
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