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Fuel Pressure Regualator?

Daboss

By Daboss,
in Engines & Forced Induction

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Daboss Experienced

Daboss

Posted
Posted

Hey all just poppin in real quick to ask your opinions on this. I am installing a fuel pressure regulator and adjusting the level to 40 psi without vaccuum if it isn't there already. My question is do I need to take my car for a retune after I have done this?

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https://www.sau.com.au/forums/topic/185641-fuel-pressure-regualator/
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Birnie Veteran

Birnie

Posted
Posted

No you can't adjust the Fuel Pressure via the ECU, well not that i know of.

The after market Nismos have a screw attatchment i believe to adjust.

If you're using an AFC, i'm assuming your mods are on the lowish side at the moment?

Not worth worrying about.

Standard is fine as long as your injectors are pushing out enough.

People keep the standard Nissan FPR above 300rwkws.

abu Grand Master

abu

Posted
Posted (edited)
No you can't adjust the Fuel Pressure via the ECU, well not that i know of.

The after market Nismos have a screw attatchment i believe to adjust.

If you're using an AFC, i'm assuming your mods are on the lowish side at the moment?

Not worth worrying about.

Standard is fine as long as your injectors are pushing out enough.

People keep the standard Nissan FPR above 300rwkws.

Sorry what I meant was if he is getting the car tuned with something that controls fuel, that will increase the fuel flow, so in that sense there is no need for a after market FPR as the stock one will provide enough pressure for whatever he needs to do.

If he does't have any form of engine managment which controls fuel, which I now know he doesn't, as he only has an AFC.

You will need to get it tuned otherwise it will wont run right.

Edited by abu
Daboss Experienced

Daboss

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  • Author
Posted
as soon as you adjust the Fuel pressure, you will need a complete retune.

I don't advise this if you have a Standard ECU and Piggy back setup.

WHY wouldn't you advise this? Even if its only to make sure I have standar or a lilttle more than standard fuel pressure in the fuel lines?

GeeTR Grand Master

GeeTR

Posted
Posted (edited)
WHY wouldn't you advise this? Even if its only to make sure I have standar or a lilttle more than standard fuel pressure in the fuel lines?

Clearly, if you'd managed to set it back to the exact same base pressure your OK.

I'm not sure exact base on a R33 RB25, somewhere between 43 - 45 i believe. Like you suggest, if you don't want to find a wide band to stick up its bum, just leave the pressure a little high to be safe.

EDIT: Mafia suggested it, because if your asking the Q: then theres a chance your not aware how changing the base pressure behind an injector will effect AF ratio's through the WHOLE rev range, amongst other fundamentals. The ECU has no idea about fuel pressure so setting the pressure too low and giving your car a hit could kill it promptly... hence why you need to set it back to the orig, or a little higher to be safe.

2nd EDIT: Corrected spelling, how anyone can understand my babbling errors, ill never know :P

Edited by GeeTR
blind_elk Grand Master

blind_elk

Posted
Posted
Hahah sorry what I meant was, if he is getting it tuned then fuel would be increased via tune, so in that case no need for a PFR as a piggy back ECU or after market ECU has provision to change fuel flow.

But if he is only running an AFC, then yeah they can't play with fuel.

Do you know what you are talking about? He is installing a new Fuel Pressure Regulator, not a PFsomething ECU. The ECU CANNOT control the fuel pressure behind the injector; that is controlled by a mechanical device, the FPR.

Unless the pressure being set is significantly different from standard, it would not be absolutely necessary for a re-tune.

The Mafia Grand Master

The Mafia

Posted
Posted

why the hell would you bother with a FPR if you are still running the factory ECU? Whats a AFC or SAFC going to do? Bend the AFM signal, after you've upped the fuel pressure? Whats the good of that? Tell the car its running rich on the AFM and then up the fuel pressure making the car run like crap?

And you're doing this without a Wideband by the looks, which will be a disaster.

Its a COMPLETE waste of time, unless you are chasing 350rwkw or more, you have aftermarket injectors, and aftermarket ECU, and a larger turbo.

Also, the factory Injectors are madness to run with higher pressure, as they could leak, get stuck, etc, creating lean condition. Engine goes bang, and then you regret playing with something you shouldn't have been, even though it wa a complete waste of time anyway.

You haven't stated your mods, so basically you are asking us how long is a piece of string....

I am running 300rwkw WITHOUT a aftermarket FPR, all I have is a Nismo 275lph pump in the tank, nismo 555cc injectors, and a powerfc controlling them.

Sell the FPR, sell the AFC\SAFC or whatever you have, and buy a power FC.

Daboss Experienced

Daboss

Posted
  • Author
Posted
Clearly, if you'd managed to set it back to the exact same base pressure your OK.

I'm not sure exact base on a R33 RB25, somewhere between 43 - 45 i believe. Like you suggest, if you don't want to find a wide band to stick up its bum, just leave the pressure a little high to be safe.

EDIT: Mafia doesn't suggest it, because if your asking the Q: then theres a chance your not aware how changing the base pressure behind an injector will effect AF ratio's through the WHOLE rev range, amongst other fundamentals. The ECU no idea about fuel pressure so setting the pressure too low and giving your car a hit could kill it promptly... hence why you need to set it back to the orig, or a little higher to be safe.

No I wasnt thinking of setting it lower.I was just going to set it to a base line pressure of 40psi if it wasnt there already. I had the thought that if you get it back to stock or a little more than stock you should be able to get 1-3 rwkw increase. Is this correct?

GeeTR Grand Master

GeeTR

Posted
Posted
No I wasnt thinking of setting it lower. I was just going to set it to a base line pressure of 40psi if it wasnt there already. I had the thought that if you get it back to stock or a little more than stock you should be able to get 1-3 rwkw increase. Is this correct?

Define "a little more" .... you mean “a little less” yah?

Technically if you leaned the motor out, yes it could make more power, but this is going to effect the whole rev range, so idle, cruise, WOT, and is highly un-recommended

I suggest, if your not doing many mods, you ditch the FPR (or if your hell bent, keep and set to close to stock base) and use your SAF to tweak the fuel accurately in the cells you want, that’s what a ECU / Piggy back is for.

As others have mentioned, if plan to make some real power, then ditch the bender, grab a PFC for $900 and use proper injector modulation to control the sized squirters of your choice.

Daboss Experienced

Daboss

Posted
  • Author
Posted
Define "a little more" .... you mean “a little less” yah?

Technically if you leaned the motor out, yes it could make more power, but this is going to effect the whole rev range, so idle, cruise, WOT, and is highly un-recommended

I suggest, if your not doing many mods, you ditch the FPR (or if your hell bent, keep and set to close to stock base) and use your SAF to tweak the fuel accurately in the cells you want, that’s what a ECU / Piggy back is for.

As others have mentioned, if plan to make some real power, then ditch the bender, grab a PFC for $900 and use proper injector modulation to control the sized squirters of your choice.

Ok thanks man will do.Thank you all for the quick responses and advice you gave me helped out alot.

siddr20 Grand Master

siddr20

Posted
Posted

Most tuners recommend fuel pressure regulator when installing an safc or neo.

I have spoken to two very good tuners, and both recommened buying it.

Obviously you dont have to, but both tuners have said that it will aid a little and push out a bit more power..

I never really asked in depth information, as i was just inquiring about the price.

Birnie Veteran

Birnie

Posted
Posted

I call shananigans.

Only need to replace the FPR if your injectors run out of puff, as a cheap alternative to injector upgrades.

If they are putting thru the correct amount of fuel determined by the tune, why do you need to push harder?

Better off replacing the Pump for a good fuel supply, not the FPR.

When you are looking at Injector upgrade which is most likely..

there are the 2 options.

1) replace the injectors or 2) replace the FPR if you aren't going to much higher.

My Tuner recommened the FPR when going over the 200 towards the 250 but i still choose the injectors, cause i wanted to :thumbsup:

GeeTR Grand Master

GeeTR

Posted
Posted

Afraid we are all saying pretty much the same thing :D

The one delta we don't know is because DaBoss hasn't mentioned how far he'll go with mods. A pressure bump and piggy back tune's clearly going to be cheapest.

Tuners recommend a FPR when using a bender cus its the cheapest band aid solution to get good results.

Daboss Experienced

Daboss

Posted
  • Author
Posted

You haven't stated your mods, so basically you are asking us how long is a piece of string....

I am running 300rwkw WITHOUT a aftermarket FPR, all I have is a Nismo 275lph pump in the tank, nismo 555cc injectors, and a powerfc controlling them.

Sell the FPR, sell the AFC\SAFC or whatever you have, and buy a power FC.

Sorry bout that usually do just forgot car is a 95 gtst current mods fmic, pod, 3.5" turbo back exhaust, ebc at 10psi lo and 13 hi and now the was thinkng of puttin a fpr in.

Afraid we are all saying pretty much the same thing :nyaanyaa:

The one delta we don't know is because DaBoss hasn't mentioned how far he'll go with mods. A pressure bump and piggy back tune's clearly going to be cheapest.

Tuners recommend a FPR when using a bender cus its the cheapest band aid solution to get good results.

My goal is to get around 200rwkw out of my basically stock car safely thats all I want that is the furthest I am going but, I want the most I can get out of it without changing engine internals and turbo just basically bolt on mods.

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