ABOUT: FSE Boost Valves/Malpassi Fuel Pressure regulators

[Aaron]

Yeah this one nearly fell in half, lost a few litres of fuel onto the ground but once re-tightened it's all good.

Now a few days and about 100km on the new gauge and there's no trace of leaking so I think it's another job I can cross off the list!

A.

[predi]

I read all the topic, but as my native language is not English I had trouble understanding few things.
So to conlude (correct me if I'm wrong):
there are two types of FPR:
1. with the constant fuel pressure
2. with rising rate fuel pressure

Q1: As I understood the 2nd type is better than 1st one, but didn't understand whether 1st type is any good at all? does it give a noticable difference?
Q2: Are these on Ebay for 30$-50$ any good? what are the differance between FSE any Ebay ones? Are there any risks on buying cheaper ones?

Q3: (talking about NA engine) Does FPR really forces more fuel into the engine? I mean if ECU sees more fuel entering, doesn't it shortens the opening time of injectors (I don't know how to exactlly explain it in english :/ ), resulting in less fuel (less meaning the same amount as before) entering the engine?

[Cosmo Dude]

Predi,
Fuel pressure regulators use the vacuum from the engine to control fuel flow. Most factory fuel pressure regulators are set more lean so that the ECU can measure the exhaust as lean and increase the duration of the injector pulse, this is better for fuel economy and emissions.
Having an adjustable regulator gives you the flexibility to have the engine run a little rich before the ECU corrects the injector pulse from running rich.

As for e-bay...
I would only buy from e-bay product that I had researched and was prepared to buy from a shop.

[Dogo]

I dont think there are constant pressure regulators. The normal FPR rises the fuel pressure in response to intake manifold pressure ( with the vacuum line ). The aftermarket ones sometimes rise at a higher rate , and usually also let you adjust the base pressure.


Ebay is unfortunately being mis-used by people selling dodgy fakes - the whole site is getting a bad reputation from these guys.

Its best to just buy from a shop. If something is super-cheap on ebay , there's probably a good reason. With fuel related modifications, you dont want anything to go wrong else you'll risk a fire !

The ECU probably does some minor adjustment with the reading it gets from the oxygen sensor, but for acceleration it relies mostly on the air intake sensor.

[Cosmo Dude]

Originally Posted by Dogo

The ECU probably does some minor adjustment with the reading it gets from the oxygen sensor, but for acceleration it relies mostly on the air intake sensor.

Closed loop: ECU monitors exhaust gasses and alters injector pulses to meet the engines needs.
Open loop: ECU uses best guess and ignores input from the exhaust gas oxygen sensor.

Closed loop only works when the exhaust is up to temp but switches to open loop with WOT (wide open throttle) conditions.

[lantisv62500]

Adjustable fuel regulator are generally seen as a way of providing more fuel or for fine adjustment, but as with all short cut mods can make more problems if the pressure is increased too much or too little.
Something that is always overlooked is the fuel filters and the fuel pump.
By increasing the pressure are you going to get more FUEL VOLUME.
For a short period YES but then the fuel pump may not be able to maintain the volume required and then the mixture will lean off causing you much more expensive issues.
When I upgraded to a KLZE the standard V6 2litre fuel pump was not up to the job at all. (Major leaning out after 4000rpm)
I replaced the standard item with a higher volume in-tank fuel pump from a Nissan Skyline GT which I think was rated for up to 400hp engines.
(Very easy mod to do.)
Fuel pressure / volume issues GONE, and performance great and no affect on economy.
I have a air/fuel meter installed (have confirmed accuracy) and the mixture ratio are now controlled very well.
If you are going to do the FPR or increase your fuel pressure adjust it on a Dyno so that the affect on the air/fuel mix is monitored.
A little bit spent now may save a lot in the future.

[Dogo]

Closed loop: ECU monitors exhaust gasses and alters injector pulses to meet the engines needs.
Open loop: ECU uses best guess and ignores input from the exhaust gas oxygen sensor.

Closed loop only works when the exhaust is up to temp but switches to open loop with WOT (wide open throttle) conditions.

That much I know but surely there's a "Oh-sh*t-Im-running-too-lean/rich" safety measure ?

[lantisv62500]

When you go WOT the ECU then runs on set programmes (maps) that the ECU holds.
The readings from the O2 sensor is disregarded therefore the engine could be running too lean or too rich.
If you have a heavily modified motor then it would possibly pay to go to a after market ECU that can be adjusted and set up for your engine.
With the V6's and their VRIS inlet manifold valves you may have to take them out or set them open as I do not think the aftermarket ECU's can be programmed for them.
I installed a air/fuel ratio meter that takes readings from the O2 sensor and that has proven to be very accurate and helpful sorting out issues.
Otherwise go to a good shop with Dyno and get it checked.

[Putonyourshoes]

how much are these things? and are they worth it?
are these the things that make "whale like sounds?"

[Cosmo Dude]

They are silent but some come with a cool little guage
One will find its way onto the V6 when I start messing around with fuel delivery.

[Cosmo Dude]

Autobarn has a Speco FPR for $60ish and Malpassi for $180ish. Malpassi has a good name and is worth the $ IMHO.

[Putonyourshoes]

are they hideable? hahahaha (p plater)

[Cosmo Dude]

They can go almost anywhere on the return fuel line. The further from the vacuum source the less accurate they can be. If you had one without a guage then plod will probably not notice it.

[Putonyourshoes]

will it get rid of my lack of low end torque?
welll.. not get rid of but will it help my low end torque that i lost with the exhaust and cai?

[Cosmo Dude]

Originally Posted by Putonyourshoes

will it get rid of my lack of low end torque?
welll.. not get rid of but will it help my low end torque that i lost with the exhaust and cai?

The magic eight ball says...
Buy a book on performance tuning. The information within this tomb will bring you understanding.

[Putonyourshoes]

haahahahaha thanks mate.

[Ethos]

Hello guys i have a fuel pressure reg fuel rail and injectors are stock can you please tell me how much pressure the rail can take before failure my car is a n/a 95 a bpze engine

[danbowe84]

just a quick question on fpr, i was told to install a malpassi after the standard fuel pressure reg. didn't think to ask why.. stupid.....thus was to get my injectors up to required 300cc/min has anyone heard of doing it like this?(running aftermarket fpr after stock item) i thought maybe cause like someone earlier said the stock fpr is built into the end of the fuel rail and didn't realize they have adapters(does any one have a link)

[Clean_Cookie]

You replace the stock item.