rx7legend

hi, i was just wondering what is the correct pressure i have to set my aeromotive fpr at idle. right now is at 22 and it's fine but if i try to go more than 27 it will start backfiring, at 27 it will backfire at 6000rpms and if i go up, well it backfires lower. at 38 that i first had it it was backfiring at 4000rpms. thanks and please let me know so i can take the car to the dyno to tune it.

brent clement

Need more info, I run mine at about 38-40psi at idle. Are you running the stock fuel pump and wiring? If the pumps not stock don't use the factory wiring it varies the voltage and generally doesn't have the current required to run an aftermarket or larger than stock pump properly.

Brent

rx7legend

mods are: aeromotive fpr, walbro 255fp rewired, rb turbo back, koyo rad, 800cc secondarys, safc II, spalm e-fan, turbosmart bov, turbosmart boost controller, tid mod, right now boost controller closed so psi are stock.

Digi7ech

iTrader: (1)

My initial atmospheric rate is 38psi.

Rx7TyreBurna

iTrader: (1)

When you are setting it, make sure you are disconnecting the vacuum hose from the FPR...

Or that is what I have been told...

classicauto

iTrader: (3)

Set the base pressure with the engine off, pump cycling.

38-40psi as Brent said (35 is stock)

rx7legend

at 38 the car was acting really bad, incredible bad smell it burns your eyes no joke and it didn't want to pass 4000 rpms, it was very rich that's why i had to lower it, if i go back to 38 it will do the same thing as it did before. at 22 the car would rev incredibly good till redline but at 38 it wont come close to 5000rpms and it will hesitate and backfire.

rx7legend

i also have the safc at 0% high and low, should i also work on the safc or just leave it alone and work in the fpr to correct this problem???

rx7legend

well i took classicauto advise and set the pressure at 40psi with pump cycling, i took it for a spin and it's very smooth i hit it on 2nd gear till 6000rpms and it pull really hard, i only hit it on 2nd gear to test it. also my boost controller is closed why do i boosted 10psi??????

NZConvertible

Stock static fuel pressure is only 36psi, so at 40psi you’ll be running ~5% richer than you should be all the time and be down a little on power as a result. Either turn the fuel pressure down or go get the S-AFC properly tuned. Otherwise you’re just wasting gas unnecessarily.

Because that’s the boost you get from your turbo/engine/intake/exhaust set-up. A boost controller can only raise boost, not lower it, so without unless you restrict intake/exhaust flow or increase wastegate flow, that’s as low as you can go.

brent clement

Now that you've got it running better get a wibeband or get it on the dyno before you end up popping the motor. You'll want to tune for about 11.5 afr under boost and I like to tune for about 13.5 under light throttle. Also you should hook the safc to the boost sensor, you'll only get a good tune under full throttle using the tps, since it goes wide open so early. That's assuming you have an s4, either way it's much safer to tune with the signal from the boost sensor since it will add fuel based on boost so if you happen to build boost early on a cold day you'll be ok.

Brent

rx7legend

thanks for the input guys, i will tune the car tomorrow on the dyno, i was just setting the fpr right before i go there hopefully will get better results than last time. looking for 230whp and the car is an s5.

rx7legend

ill turn the fpr down to the correct psi. thanks