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S14Redtop
06-08-2005, 06:35 PM
I've had a fuel issue for some time now that i'm trying to narrow down. I have nismo 740cc', z32 maf, walbro 255, stock fuel rail, fpr running 50psi base and jwt ecu and safc. When we do dyno pulls with the car we are always having to add fuel with the SAFC (up to 20%)to get the AF right. I have tried my entire setup on cwdmark's S13 and the AF is perfect 11.8 without the use of SAFC.

While watching the AF% on the SAFC, it never goes above 48%. I would think that putting down 415 whp would cause the maf to be reading higher, like in 60-70% range.

Any suggestions as to why my fuel is F'ed up would be appreciated.
thanks
m

TS4l
06-09-2005, 09:41 AM
My car on low boost hits 48%, and when on the dyno that was like 210! Seems like you are right it should be way higher, is there any leaks in your intake after your MAF that air is getting around! If it were a boost leak it would run rich, but if somehow the intake is leaking it could run lean, or the MAF sensor is screwed up. Good luck, my friend has a simalr problem where his MAF reading drops low and his car runs lean at part throttle and border of vacuum and boost! If we figure that out I'll let you know what we find so hopefully it can help you too! Good Luck!

-Jason-

cwdmark
06-09-2005, 10:59 AM
maf, injectors, ecu are all fine because we transferred them to my car to test them out. my only guess is that there's a leak someplace or bad fuel lines. we should get out the pressure tester.

S14Redtop
06-10-2005, 06:33 PM
If there is a leak somewhere it should run rich I would think. I suppose the fuel lines could deffinately be an issue, but with so many other people running the same kind of power on stock fuel line and stock fuel rail...but i might be wrong.
There also might be some sort of interference in the MAF wire under heavy load that might give low readings.

anything else?

mark

rn240sx
06-19-2005, 08:27 PM
When im pushing 15 psi which is about ~300 whp.. my afc displays 49% on the afl readings...
When im at 18 psi.. im reading about 57% if i recall correctly...

S14Redtop
06-19-2005, 09:16 PM
yea...see mine seems a bit low. But now we have found a big thing that might be the cause of all my issues. The voltage at the ECU is about 12.5 at idle and about 10.8-11.0 as rpm rise. The voltage in the engine bay and at the battery is 13.8!!!

mark

cwdmark
06-19-2005, 10:17 PM
yea thats awesome you found the prob! good luck fixing it http://forums.freshalloy.com/images/graemlins/smile.gif