finalstage1

ok , say i put an adjustable fuel reg. on my car and set the fuel presure where i want it . will the computer lean it out/richin it up so it will be back to the stock a/f ?
is an adjustable reg. useless ?

MEAN LT1

iTrader: (2)

The computer will compinsate. Usleless

jm93camaro

iTrader: (2)

Pointless.

UA-Plumber

iTrader: (2)

This guy says otherwise...............

Dyno Run

Formula350

iTrader: (3)

Not sure how you tune for more pressure, especially on my Speed Density (sine I've been tuning a file), but when I chipped my 91 TPI and put the adjustable around 49psi, I know there was a difference in performance.

Honda Hunter

iTrader: (8)

I dont understand why they would be better for a SD car or a MAF car. Then there are people that swear by them. I have one laying around brand new I may just throw on.

LT1BRN

iTrader: (1)

i cant understand why is it good, I'm yet to read some logical explanation.

if u ever read any, post it, that would useful.

Hot94Z28

I see using it if you run a dry nos set up. Then on the dyno run it said after time the computer changed the pulse withs to back were they were and gained no power in the long term effect. I changed mine cause the stock one was bad.

anaik

Did you read this note under the graph?


NOTE: One thing that I have found after some time with this mod is that the stock computer is quite smart. After lowering fuel pressure to achieve a better air/fuel ratio, the computer sees this at part throttle and adds injector pulsewidth to compensate. Basically, horsepower fell back off to where I started from. While normal trains of thought tell us that since O2 values are not measured during wide open throttle, that fuel pressure should have a long lasting effect here. Actually, it does not. The computer uses the last known long term fuel trim integer at WOT, which is to add fuel since at part throttle it has adjusted for being too lean.

93-vr4+transam

iTrader: (1)

the only time I can see a afpr coming in handy, is if you upgrade to a walbro 255 fp. I put one in my car and was getting way to much fuel pressure. 48 with line on, and 55lbs. with line off. had to put one on to lower it down. and maybe if you go with bigger injectors to adj. it...

Honda Hunter

iTrader: (8)

Read the last sentence in post 8 and re-read post 9. In the end I believe it's proven you must go through the computer to make long standing correct adjustments.

93-vr4+transam

iTrader: (1)

well that may be true, but I have a autometer elec. fuel pressure guage, and for the first week it was reading 55lbs. with the fpr line off and 48lbs. with it on, after the walbro 255 fp went in. until I put on a afpr. and made the adjustments. so maybe the computer did make the changes but I figured my fp guage dosent' lie...

Honda Hunter

iTrader: (8)

Was your stocker bad?

93-vr4+transam

iTrader: (1)

well I don't know maybe it was.. maybe when I put in the walbro then it couldn't adj. right to the higher fuel pressure...

anaik

I've read of other people replacing with a Walbro and their fuel pressure going up.
The PCM has limits to the changes it can make. It can use the BLM's to add UP TO 25% extra fuel (BLM = 160), or reduce the fuel by about 15% (BLM = 108). It can then continue to raise or lower the short term corrections (INT's) to net you even greater corrections.

UA-Plumber

iTrader: (2)

No I didnt, thanks for bringing that to my attention.

Bryan

BRIANLT1

Maybe I am missing something here? The computer can adjust AF ratio or injectors but isn't the fuel pressure regulator adjustment make the available pressure for the computer to adjust to what it see fit to do? I am running aftermarket harness so maybe I do not have all the sensors hooked up as per stock.

All I can tell you is adjusting the regulatot makes a difference that I can feel?? If the stock regulator is only adjustable to say 45lbs and you can set a Aeromotive at 65lbs that does make the available pressure higher correct???

96capricemgr

iTrader: (1)

The computer controls fuel based on programmed in injector size rating and uses open time to control fueling, raise or lower pressure without reprogramming for the new flow rating and the pcm then does it's figuring based on incorrect injector sizing info. The O2s are used at part throttle to maintain 14.7:1AFR and the computer is capable of learning and in the case of needing to add furel at part throttle it aplies what it has learned at WOT. Stock tuning is very rich so a performance gain can be had leaning it out BUT doing so with an adjustable regulator will lean it out at all times not just WOT as such the pcm will see it with the O2s and begin to learn and eventually completely "correct" for your halfassed attempt at tuning.

An AFPR should be used as a fuel system component NOT a tuning tool there is a difference.

Hersker Hans

im considering buying an AFPR instead of a normal FPR, ive got a walbro 255, and im just gonna run the engine on stock fuel pressure which is 58 psi. But then i have the ability to adjust the pressure for tuning with hptuners.

which afpr should i get? there is a few to choose. found them from 5 to 100 dollars on ebay buy it now prices. should i get aeromotive? or is there any other a but cheaper ones. I dont want boost pressure to adjust my fuel press even though i might consider getting turbos, i want a set fuel press and tune it with different injectors and hptuners. Or should the fuel pressure adjust with boost you think?

streetwarrior96

when I put mine areomotive FPR in I set it to 38 psi @ idle (factory setting)... where it was supposed to be at. I let the tuner take care of my AFR. I honestly don't think that by changing your FPR your gonna feel it. Like 96capricemgr said FPR is just a component.