Fuel Pressure Regulators???? how to choose

Go with KIRBAN, it is the only one that holds any fuel pressure when the car is shut off. Your start cranking time will greatly increase with the BBK and Aeromotive. Some people like this to build oil pressure, I hated it. Makes it look like you have a car that does not want to start. Another option is to turn your key to the "on" position for 10-15 sec before you start the car, this will give you the fuel pressure you need to start. I would just get a KIRBAN.

If you plan on having just an on-rail fuel regulator gauge, then use KIRBAN. If you plan on needing the extra port on a regulator to run a gauge elsewhere either on the cowl or inside the car, then get the ACCUFAB. I had that one and it was a very nice piece.

R.J. said:

Go with KIRBAN, it is the only one that holds any fuel pressure when the car is shut off. Your start cranking time will greatly increase with the BBK and Aeromotive. Some people like this to build oil pressure, I hated it. Makes it look like you have a car that does not want to start. Another option is to turn your key to the "on" position for 10-15 sec before you start the car, this will give you the fuel pressure you need to start. I would just get a KIRBAN.

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I have an Aeromotive and Ive never had any start problems...just like stock.

Kirban, Accufab and Aeromotive are all good. I use the Kirban.

When is one needed? As soon as possible. Anytime you can make adjustments after installing mods is a good thing.

VibrantRedGT said:

Kirban, Accufab and Aeromotive are all good. I use the Kirban.

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I had an Aeromotive and after 1000 miles it started to leak fuel like mad and almost burnt my car up.

GO WITH A KIRBAN!! Hands down the best!

S/CBlack95GT said:

I had an Aeromotive and after 1000 miles it started to leak fuel like mad and almost burnt my car up.

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I've heard that story so many times about the Aeromotive ones...crapola

You have to be careful with a fuel pressure regulator. The EEC in our cars will, over time, regulate the fuel pressure down to the stock setting of 39 PSI unless you adjust your computer to accept the increased setting.

So unless you get a chip burnt or self-tune, you're essentially wasting your money!

Adam

As Adam suggested, the computer will adjust the injector pulsewidth (dwell) to accomodate an increase in FP. Foxes use AFPR's (even near stock) because at WOT, there is no fuel trim. But since SN's have WOT (OL) fuel trim, I dont think they are as useful till the computer is unable to adapt the pulsewidth enough to keep the A/F stoich.

Just my thinking.

Good luck.

I have given this topic a great deal of thought and talked about it with peeps who I consider to have a pretty good bit of knowledge about self tuning.

There is always the chance of this happening.

even if you do get the fuel pressure adjusted for your desired ratio while at the dyno using their wide band .........

several days or weeks later ... the pcm has changed things and your ratio is now not the same as it was when you left the dyno.

It might not change at all
It might chage a just little
It might change a whole lot

The whole purpose behind the pcm's adaptive strategy is to keep things within a range as things change like sensors getting old and the like.

I am not necessarily against afpr's .................
I just don't think they are as effective as some think.

I've come to think one could follow these guide lines for a method of stable mechanical fuel adjustment using an afpr.

1) Reset the pcm
2) Base line WOT blast with wb data
3) Analyze base line data

At this point in time, the pcm will not have had enough data points gathered to start the adaptive process ...... if it is gonna do it all.

4) Make your pressure adjustment
5) WOT blast
6) Compare 2nd blast data to base line data

What I am unsure about is (I've never owned an afpr btw) ...... how many data points before the pcm will start to make changes. I guess you could always reset the pcm between test runs to be safe.

The objective to this idea would be that when you went to the track ......

you would reset the pcm and you would be duplicating the conditons you were at when you set the mechanical adjustment.

The ratio should be close to the same if not the same.

anyway

Just a thought or two and none of it backed by any kind of data so don't anybody take this stuff as factual or some kind of tuning secret, lol. Just me thinking out loud so if any of you guys can share your findings or show me I'm way out there in left field ................ I would welcome your thoughts or input.

xkuntrycowboyx ... none of this helps you I know .....................

but

I'm tryin to find someone with some factual stuff about this topic

Grady

I've heard that story so many times about the Aeromotive ones...

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Hmm..wonder why that is...here's another one..bought a BBK..it started leaking where the large tube is pressed in...bought Aeromotive b/c they're supposed to be great quality. I was happy for a while, looked good and the lower part was machined from one piece so I knew I wouldn't have the problem I did with the BBK unit...eventually it started leaking out the vaccumm hose and upper/lower seam. Now I just use the stock FPR, correct size injectors and a little TwEECing..no probs..

This is not true about our cars adjusting the AF/R back to the stock setting at WOT. Our cars do not read the O2s at WOT so if you crank up the fuel pressure the AF/R will be richer at WOT. The computer has a "known" fuel pressure as a baseline to go by. For example, the base fuel pressure at WOT and full load may be 40psi. Now if you increase the pressure to 60psi the computer still thinks it is at 40psi because it has no way of knowning more fuel is being delivered. Therefore the AF/R is richened.

Now it is true that at part throttle the computer will set the AF/R back to the stock setting. This is because the O2s are being utilized. If the computer reset the WOT AF/R back to the stock setting then every supercharged and turbocharged car with an FMU would grenade a few months after their first dyno tune.

Shaun, my understanding a little bit different. Let's get to the bottom of it, if we can.

During OL, the adaptive control does not update, but it utilizes info from the last CL operation. So with an increase in FP, as soon as CL is reached, the injector pulsewidth is dialed down to reach stoich. All other accomodations for the increased FP are made as well. Then in the next OL session, this adapted control is remembered and utilized.

HISSIN50 said:

Shaun, my understanding a little bit different. Let's get to the bottom of it, if we can.

During OL, the adaptive control does not update, but it utilizes info from the last CL operation. So with an increase in FP, as soon as CL is reached, the injector pulsewidth is dialed down to reach stoich. All other accomodations for the increased FP are made as well. Then in the next OL session, this adapted control is remembered and utilized.

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This is my understanding as well. It may not READ the O2's, but it uses the correction factors it's already determined in closed loop.

Personally, I have a Kirban, solely because it was my understanding at the time that I needed one for boost referencing the fuel pressure (increase FP under boost).
I've since HEARD that the stock one MAY do this, but it's too late for me.
I have it adjusted to the stock pressure....

What's the purpose of using the aftermarket FPR's over the stock one anyway? I understand using a bigger fuel pump and injectors, but why the FPR?

Zero Signal said:

What's the purpose of using the aftermarket FPR's over the stock one anyway? I understand using a bigger fuel pump and injectors, but why the FPR?

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Aye John, that is part of what is being debated here, it seems. I am not one (like Grady - and we seem to be in the minority) to use an AFPR.

They are nice for serious mods, where the adaptive control hits its limit. For instance, if running lean and out of adaptive limits, bumping pressure will allow the puter to find stoich again. But if it is already stoich, IMHO an AFPR does not do much for ya. I know I am in the minority here, so let the flaming begin.

Good to see some discussion on this topic.

Good to see some discussion on any topic ... these days

Get something to drink or a snack before starting on this one

This is the perfect time to point out that any kind of topic a 94-95 guy wants to do some exhaustive research on .......................

he has to endure 90% of Fox bs before he gets to data that pertains to his car

The Fox pcm operation is a good bit different than our pcm's.

I know for sure adaptive has a limit of adjustment

What I am unsure about is the difference between Fox & us as far as throwing the CEL

I do know on our cars, the CEL will be envoked at times if adaptive has reached its limit.

The explanation JT gave is the one you mostly see that is out there.
however
I have seen some say they are not so sure our pcm's work like that and I'm sure their suspicions are based on data they have gathered.

You have the ability to see realtime data which is great
but
there are times you have no reason for why you see ...... what you see

Examples

1) I have seen my final wot af ratio drift a small amount over a long preiod of time.
I have no answer for this

2) I have seen my final wot af ratio change with a difference in outside temps.
I reported this finding on the tuner forum and it caused all kinds of talk about why it could not happen cause the maf would compensate for temp changes and other various reasons.
Hey ... all the talk was interesting ... but ... I still had hard data showing what I said took place ... did in fact happen

My Closed Loop tune is pretty stable and the Adaptive Strategy does not make very big changes
but
it is impossible for ANYONE, even a Pro Tuner, to create a tune where the Adaptive makes NO changes over time.

Having said that ...... I suspect ... I repeat the word ... SUSPECT ... Open Loop does in fact get some input from Closed Loop Driving Conditions and the pcm makes some kind of change that does in fact ... effect Open Loop Driving Conditions.

A good bit of Fox stuff does not apply to our cars but it has been mistaken as fact for our cars as it IS fact for the Fox cars.

The setting of the tps comes to mind.
Some swear setting it helps ...... some say no it doesn't

The adjustment of fuel pressure is kinda in that camp I guess.

Here is a thing or two I do know for sure about the pcm and fuel pressure.

1) From everything I have seen, the pcm has no knowledge about fuel pressure.
2) The pressure value like the spark value is assumed by the pcm to be at stock value.
3) Hosing around with the pressure will most definitely effect the Closed Loop operation of the pcm and its Adaptive Strategy will try to negate that mechanical adjustment.

Now it is true that WOT driving conditions are in the Open Loop Strategy of the pcm
but
unless you got a way to tell the pcm you want to operate 100% of the time in Open Loop ... it don't make no difference anyway.

Having said that we come full circle in this discussion and are back to where we started.

I have this opinion on AFPR's and their use for 94-95 cars.

Ford designed the pcm and all its supporting sensors for stock pressure.

Even if running elevated pressures is effective for a fatter WOT ratio ...
those elevated pressures are gonna hose up drivability.

For Our Load Based PCM's ....................
the most accurate way to compensate for more airflow & fuel is to

Tell the pcm the truth about airflow & fuel
as opposed to
1) The cheat method after-market maf makers have devised
2) Mechanical adjustment of fuel pressure

Summing up and Final Thoughts here

Using Elevated Fuel Pressure is not without its draw backs
so .........................
even though I don't understand everything about what is really going on with this topic ...............

Those known draw backs are enough to tell me ...

AFPR's may HURT more than they HELP

Grady