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FSE fuel pressure regulator (Power boost valve) The facts...


TLicense

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Well here it is chaps. The facts about the FSE fuel pressure regulator (Power boost valve).

 

My set-up is as follows:-

 

'93 J-Spec TT with stock sequential twins.

Stock 440cc injectors.

Warlbro 255lph fuel pump.

AEM ECU.

AEM 150psi fuel pressure sensor plumbed into FSE port.

Boost is controlled by wastegate actuator = 14psi.

Stock fuel lines *except* -6 feed line from fuel pressure regulator to fuel rail

And of course a FSE fuel regulator.

The static (base) fuel pressure was set by Leon at JPS when he mapped my car. This was set to 50psi. For reference the stock pressure is 36psi.

 

I've attached both an AEM log extract, and an excel spreadsheet for those who don't have the AEM software.

 

The summary is this:-

My first run:-

Under -12psig vacuum (on over-run) my fuel pressure is 24psi

At 0psig (As boost is coming on) my fuel pressure is 44psi

At 14psig (full boost) my fuel pressure is peaking at 56psi, but dropping with revs to a minimum of 42psi.

 

This is basically saying that under vacuum the FSE is increasing boost pressure on a 1:1.6 rate. Under boost it's rising at a rate of approximately 1:0.9.

The reduction of fuel pressure under revs must be down to poor fuel supply. Strange as I have a warlbro 255lph fuel pump fitted.

 

My second run:-

Under -12psig vacuum my fuel pressure is 22.4psi

At 0psig my fuel pressure is 46psi

At 14psig my fuel pressure is peaking at 50.2psi

 

Under vacuum the FSE is increasing boost at a rate of 1:1.9 Under boost it's rising at a rate of 1:0.2psi.

Their wasn't a drop in fuel pressure on this run, however their was a much smaller increase in revs, (4000rpm on the first run vs 1000rpm on the second) so this is something I'll still have to monitor.

 

Conclusions:-

 

It appears that essentially the FSE increases fuel pressure under vacuum at a rising rate (something between 1:1.6 and 1:1.9) Under boost the FSE increases boost at a much lower rate (between 1:0.9 and 1:0.2)

 

Basically there is very poor repeatability.

 

This definitely explains why I've been having so much trouble setting up my fuelling.

 

Actions:-

 

My next move, will be to investigate the drop in fuel pressure with revs, and then to fit a different FPR (probably an aeromotive) If anyone wants to find out if these results are specific to my FSE then they can feel free to send me another FSE and I'll fit that and re-run my test.

I've run the test a couple of times since and will be doing it again a number of times over the next few weeks. So far everything I've found pretty much says the same thing however if I find anything else different to what I'm seeing here I'll post it up.

 

If anyone's got any suggestions/questions then feel free to mention them.

Excel Format.zip

AEM Log format.zip

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You'd have hoped for at least equal rate rises like the stock FPR seeing as it's supposed to be 1.7:1!

 

You've probably got a buggered FSE valve, which may seem like I'm making excuses for it but really it's just yet another failure of this thing. This one won't set fire to you and your car but it'd blow your engine up instead :rolleyes:

 

-Ian

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They INCREASE fuel pressure under vacuum??? I don't believe it, they should REDUCE pressure under a vac signal. I am sure you are mistaken, I can't see how they can possibly increase pressure under vac. IMO they are a load of *rap, bin it, fit the stock one, or a decent adjustable one if you NEED to alter the stock rail pressure.

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They INCREASE fuel pressure under vacuum??? I don't believe it, they should REDUCE pressure under a vac signal. I am sure you are mistaken, I can't see how they can possibly increase pressure under vac.

 

You've misunderstood Chris. It's increasing boost as vacuum reduces (ie boost is increasing) Or put another way it's increasing boost pressure at a rising rate when under 100kpa and then above 100kpa it it's increasing at a rate between 1:0.2 and 1:0.9. Look at the graphs, it's quite clear.

 

Yes you are right though with regards to it being a P.O.S. (Well my particular one, perhaps it's just one that's slipped through the Q.C. net eh?)

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Worrying reading, seeing as I have one of these...

 

Anecdotal evidence from other sources suggests I should bin it...but what to fit in it's place?

 

If your stock rail has been modified to fit the FSE then you'll have to go for an Aeromotive FPR...otherwise just put the stock one back into the rail.

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How would I know if the rail has been modified?

I know where the FSE is, with some pipes coming out of it, including some blue boost-hose, but the rail is the stock one...no idea if it got adjusted...

 

I don't have the stock one.

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Guest Terry S
How would I know if the rail has been modified?

I know where the FSE is, with some pipes coming out of it, including some blue boost-hose, but the rail is the stock one...no idea if it got adjusted...

 

I don't have the stock one.

 

 

The stock FPR will have been removed as it fits directly to the rail. An adaptor would have been bolted to the stock rail in place of the stock FPR, and a hose will go from the adaptor to the FSE

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How long have I been telling people they are pants........

 

Not long enough....(about half-way down) :p

 

Injectors, be careful that if you upgrade injectors they fit the stock rail. Also be very careful to check the impedance of the injector. The 440's will be near there limit with a Walbro and an FSE, but OK. 1.3 bar is the max on Optimax with a stock ecu and compression, don't think because you have more fuel you can run more boost. It will end in tears.

 

http://www.mkivsupra.net/vbb/showthread.php?p=144335#post144335

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