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Discussion Starter · #1 ·
I installed the cartech fmu today and have some questions about adjusting a/f.
My setup is d16y8 jrsc pushing 9psi.
walbro 255, begi 2025 fmu, jrsc map & btc mod.
The static fuel pressure with vac hose connected reads ~48psi. With hose disconnected it reads ~53. When I installed map mod the instructions said it should be lowered to 40-45 psi at 0 vac. It won't go lower than that probably because of the fuel pump.
Now at wot anywhere from 3.5-7000 rpm the a/f reads between 11.3-12.0
when I'm cruising though, (10-20 vac) and hit the throttle, the reading drops to 10 and slowly climbs to 11.2
my question is should I lower the rise rate on the fmu, or is it reading too rich because the static pressure is high to begin with?
sorry for the long post, but does anyone know what my fuel pressure should be to start with?
thanks
 

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40-45 sounds right. If you don't have an adjustable FPR, you should get one. I, instead, drilled a small hole in the stock FPR to reduce the fuel pressure, and still ran about a 3.5:1 rise rate on the cartech.
 

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exciv2000 said:
40-45 sounds right. If you don't have an adjustable FPR, you should get one. I, instead, drilled a small hole in the stock FPR to reduce the fuel pressure, and still ran about a 3.5:1 rise rate on the cartech.
Sorry to jump in but since you are on the subject. I must have misunderstand you (exciv2000). I ran my b16sir2 supercharged on the dyno with just the B&M regulator and no jrsc fmu and produce 203whp/138wtq. I also have it on p28 ecu with uberdata. I also can't lower my fuel pressure lower then 42psi with and without vacuum.
 

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Discussion Starter · #4 ·
40-45 sounds right. If you don't have an adjustable FPR, you should get one. I, instead, drilled a small hole in the stock FPR to reduce the fuel pressure, and still ran about a 3.5:1 rise rate on the cartech.
I think I'll have to do the same thing to reduce the pressure.
B&M didn't work for me, idle pressure still won't go lower than 48.
What should it be set at BTW? I know onset of boost should be 40-45, but should idle be the same or lower?
 
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