i was wondering if anyone has used one of these and how they work ?

Kevin

 

I just got mine on a couple weeks ago. It's a good upgrade over stock but not as good as chip tuning. It uses a vacum signal off of the tbi to increase fuel pressure with engine load. Mine came to me unadjustable, which sucks cause i've broken 4 torx bits in the process.

 

i thought they r supposed to be adjustable

Kevin

 

I have it and yes it is adjustable. It is a very stiff screw and you habe to press very hard in and turn so so so so slow at the same time. You will free it up. i think it gets that green paint all over it and you have to free it from that. After that it will be nice and loose and you can adjust it accordingly. Using this in conjunction with chip burning is the only way to go.

 

i was wondering canu make 1 or 2 adjustmenta on there for fuel pressure . since u have the vacuum line on there one with the vacuum for base and one without for wide open throttle low vacuum

Kevin

 

Well that is the point of the vacuum regulator it adjusts according to rpm and vaccum changes in your TBI. The higher your rev the more fuel pressure there is for this unit. You should implement a vaccum delay valve in the line to keep the pressrue from dropping off to rapidly when you come back down to an idle. Every 2.5 turns is one psi of fuel pressrue increase. It is infiniately adjustable (in theory that is).

 

Mine has no paint on it. I think they started putting threadlocker in it or something. I've heard the only way to break the new ones loose is to heat them up with a torch to melt the threadlocker, I haven't attempted it yet.

 

That "green paint all over it" is more commonly reffered to a Thread Locking compond. The most well known brand being Loc-Tite. A better way to loosen that is to heat the area with a torch (obviously with the unit removed), and it will melt the thread locker. The adjusting screw will then turn with ease. Turn the screw out, wire brush off the thread locker, and screw it back in. Re install the VRFPR, and comence adjusting.

One thing I would like to make clear here, everyone. I didn't install the VRFPR to "get more power", or to "get more fuel up top". That is NOT what the VRFPR is for. It's not a power increading "mod". Why not? because if more fuel is actually wht you need at WOT, you can easily obtain that with your stock FPR. If you adjust your stock FPR to a higher FP, and you do observe an increase in performance, you're all set. If you observe and increase in performance in conjunction with worse driveability (most likely due to a rich condition at low throttle, then The VRFPR my "band-aid" that issue. I did it as a band-aid to a poor fuel curve that my particular combo had, which resulted in poor driveability. I first tuned my engine's timing and FP to make the most possible power (track times). When I had settled on the FP that resulted in the BEST 1/4 mile times, it idled too rich, and would sometimes flood and stall when coming to a stop. I tried the VRFPR as a tool to fix this, and for my combo, it worked out really well. SO I posted here, for people who were in my shoes. Now there are a bunch of people who think it might be a good bolt on to make more power. They bolt the thing on a STOCK motor, and then bitch about how it doesn't work and it's not a good mod. Not true. It MIGHT be a good bolt on for those trying to "band-aid" a modified motor that needs a fuel curve that strays from the stock one(any engine w/an agressive, aftermarket cam, basically). IMO, if you have a stock long block, the VRFPR isn't going to help anything. Just my .02

Another point; the VRFPR DOES NOT "raise the FP at WOT". Instead what it really does is LOWER the FP at low manifold presures (high vacuum). Why am I making this nit-picky point? Because the no-vacuum FP is -or should be- your basis for everything, because that is fixed and constant. Nothing changes that except for the little adjusting screw. The vacuum refferenced FP is variable and chages with engine temp, barometric presure(weather and alt), idle speed, basically anthing that will affect your manifold presure, will also affect your FP, so it should never be set or measured with vacuum refference. Like I stated above, if you find your ideal WOT FP (either on a dyno, or through trial and error at a track), and that FP leads to an overly rich condition at idle, then install the VRFPR, set it to the SAME presure with the vac signal hose disconnected, and then connect the hose to drag the FP down, hopefully to a level that is good for your combo.

One other thing; The rate of fuel delivery fall off is tunable too, if it falls too much or not enough, let me know and I can tell you how to tune that differential between WOT fuel delivery and high vacuum fuel delivery.

 

The lower manifold presure the higer the fuel presure. Actually, you could be revvign the engine really high, at a slight throttle opening, and have LOWER fuel presure than stock! That's why you set the fuel presure w/o vacuum. THEN hook up the vacuum line. If it doesn't work out, unhook the vacuum line, plug it, and you're back to stock operation.

 

The green paint I am talking about is all over the unit not just on the torx screw. As I turned my screw the paint arround the screw flaked off and was much easier to turn. I am not talking about the thred locking compound. I should have clarified and gone into more detail than I did. You cleared a lot of people up. I know it is not a power increasing mod and that I why I got it. I thought most people understood this but I geuss I took that for granted. No biggy. I was very rich at idle and wanted a quick fix before I got into the PROM burning stuff. I was happy with my FP at WOT but not at idle. I also used the vacuum delay valve so that at higher manifold pressures the fuel pressure won't drop off so quickly and create the circumstance you described above. WOT stayed around 15 psi and idle was down around 11.

 

ok thats what i was thinking so it would lean out at idle and them have a higher fuel pressure at wot at low vacuum situations . ok thanks for the info guys


Kevin