Imran21

iTrader: (5)

Hi All,

Can someone please tell me what pressure to set the FPR at on my car?
It is a version 4 STI type R with the 440 cc injectors. I have fitted a Sytec FPR with a Sytec/Walbro uprated pump.

I believe standard fuel pressure is 3 bar so i was thinking of pushing it up to 4 bar on idle and 5 bar on throttle?? Is that ok?

Also, at what percentage would my injectors be running with this set up?

Cheers,
Imran

dunx

iTrader: (3)

3.5 bar - what use is screwing it up if you don't know what the AFR is doing ?

dunx

dazdavies

iTrader: (22)

Take the vacuum pipe off the fpr and block the vacuum pipe end.

Start the car and make sure you have 3 bar @ idle. Then reattach the vacuum pipe and tie wrap it tight for good measure.

If you up fuel pressure without map changed your car will be overfueling and run like poo.

The 440cc injectors were standard on that car so the fuel pressure shouldn't need to be changed.

Imran21

iTrader: (5)

Thanks for advice guys.

@ Daz - so does that mean i should not be using the FPR and stick to the OE set up?

Also, if i do the above test to make sure the fuel pressure is 3 bar at idle, what do i do if its higher or lower than that?

And wont the 440s still be spraying the same amount of fuel even with the FPR? Its just the pressure coming into them is increased....?? I was under the impression that if i went the 550 route then obviously i'd need to map accordingly so as not to cause over fuelling...

Thanks agian,
Imran

wrighty338

iTrader: (33)

you usually uprate the regulator if you have uprated the pressure from the pump or fitted a bigger pump. if not you still have a pump, pumping stanard amounts of fuel and the regulator putting pressure on to pump more. i dont believe pumps work well under stress either.

if you havnt done the pump, you simply need the reg set to stanard pressure

Imran21

iTrader: (5)

Hi,
As stated in my first post - i have the uprated fuel pump (255lph).
IM

dazdavies

iTrader: (22)

It's doesn't matter what pump you have on there if the reg is set for the same pressure as the OE reg then it will flow more or less flow the same.

You'll only screw up the fueling by using more pressure than what the car is mapped for.

The FSE should be adjustable. Any fuel not used by the injectors will be returned to the tank.

As said above, set at 3bar idle with the vac hose off and you'll be about right.

The standard car uses 440cc injectors. All you've done by adding a pump and reg is making the fuel supply reliable but adjustable for future upgrades.

It's very unlikey you'll be maxing the injectors out on a stock turbo unless of course the car is remapped but then your mapper will be able to tell you what your injector duty is.

Imran21

iTrader: (5)

Hi Daz,
I have a VF34 waiting to go on which i'm sure will pretty much max out the 440s.... right? Should i still maintain the pressure at 3 bar then?? On throttle the pressure increases by one bar - so that would mean 4 bar. Is that sufficient enough for the VF34?

And when i do as suggested above to set idle pressure i.e. disengage the vacuum pipe & set pressure to 3 bar - once the vacuum line is reconnected should the pressure at idle go up, down, stay the same?? And how much should it increase by on throttle?

Sorry for all the questions but i'm doing it myself as i want to learn and really appreciate the help & advice.

Cheers,
Imran

PS: Any luck with that gearbox then?

dazdavies

iTrader: (22)

Imran,

Once you swap turbo you're into remap territory. I would not advocate not remapping a car once you change turbo. A VF34 will certainly result in high injector duty on the 440's.

My honest advice here is to get some 550cc injectors and get a remap which unfortunately on the Version 3/4 means a new ECU.

That said if you have no option i'd up the pressure to 3.5-4 bar at idle with the vac hose off. If you are going to do things without a remap then the Minimum you HAVE to do is to fit a decent AFR gauge and sensor.

If you don't you're asking for trouble IMO.

Gearbox will be ready for collection on Monday.

I'll pm collection details