What kinda Fuel pressure are you guys at, at idle ??
Right now im at 34..I know thats too low..>> I was thinking 40ish ??

I would like to make any major adjustments before I get a good tune in the EU. And I know with messing with basline fuel pressure its going to effect a/f alot and I can correct that via EU

I have AEM FRP, DW 555's

-matt

 

FP at idle doesnt mean jack. Take the vacuum line off, then adjust the pressure (stock is 3 bar, 44 psi). Not than anyone on this forum does it, but a 4 bar setup works much better with side feeds.

 

Well FP at idle does mean alot becuase thats what FP your going to be seeing while cruizing, and while your passing 0 On your way to boost.

I just wanna have the correct PSI at idle, so it will the run the best and I can start doing some tuning.

-matt

 

Im telling you it means nothing because the ECU will always be at 14.7 a/f no matter what the pressure is. Closed loop operation does not care about FP.

Like i said take off the line, adjust it to 3 bar for now, then get on the dyno or use a wide band to tune it. Your z32 MAF is decent with the 370's so the worst that will happen with the 555s is run rich. That may cause some small issues but its much better than running lean. Hey what do I know my Maximas not boosted........

 

Higher the pressure = more fuel = richer

That is what I got from looking at the Deastchwerks data sheet.

 

What the he** does 3 bar mean ??

-matt

 

Its a "technical" term. 1 bar = 14.5psi so 3 bars =43.5psi.

 

What type of baseline fp are people running with 555's ??

-matt

 

Sorry! I have 370's and my FP is 36

 

Nissans are setup from the factory with a 3 bar setup, which is 43-44 psi at 0 vacuum (vac line off). FP will drop when the car is at idle, and that depends on cams, but its supposed to be around 34-36 psi. My FP at idle is 34 psi, pull off the vac line it raises to 44, which is the same pressure when running at WOT (no boost/ 0 vacuum). The stock regulator is a 1:1 rising rate.

Yes a higher pressure will mean more fuel, and a vice versa. But you dont want to go playing with it at idle, then go do a WOT run hit 10 psi (or what ever your at) and not have enough fuel. I assume your AEM AFPR is a 1:1 rate. That means once 0 vacuum is reached youll be adding 1 psi of fuel for every psi of boost. You could actually run out of fuel up top if you try and set your FP at idle. Closed loop always runs at a ratio of 14.7 a/f, even if you dropped the FP down to 20. Then you will run out of fuel while your boosting and thats a great way to blow your motor.

 

When I was at JWT having my motor tuned and dynoed, Jim set the fuel pressure at idle and then retested. According to them , on the 4th gen, start off at 43.5 lbs of pressure with the vacuum line off and then test for any pinging and raise the pressure at idle again with vacuum line off and retest until no pinging. But, you can run out of fuel pressure if you max out your injectors or the fuel pump is too small or not getting enough volts to maintain full output. As we all know if you're not sure what you are doing, don't.
Let someone with the knowledge help you!

 

Taking the vac line of is what Im telling matty to do. 43.5 is stock 3 bar, so yea thats what I said already.

 

It's all preferance, and jwt is more than credible. I would honostly rather start with a higher bfp with vacuum line off and then bring it down until ping is detected, then raise it up.