fuel pressure regulator

Discussion in 'Mechanics Garage' started by cirv, Nov 15, 2006.

  1. cirv

    cirv New Member

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    I saw an ad in the June 06' edition of Roadbike magazine page 89. It states they offer a fuel pressure regulator for the Honda VFR 800 02-05, which is supposed to improve the overall drivability and eliminate the quirks of the EFI system. I went to their web site turbocity.com. It lists the Honda VFR and the many benifits: idles at 750rpm very smoothly, accelerates without hesitations or sags,will pull a lower rmp in a higher gear,eliminates cruise surge 3500-4500rpm, smoothes throttle on/off response, softens driveline "clunk" and "snatch", and can be tuned for exhaust/intake modifications. I am new to the VFR and this site and thought you all can help with the validity of this product. I am generally of the opinion if it sounds too good to be true it probably is too good to be true. What do you think? CIRV
     
  2. im944

    im944 New Member

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    I am a mechanical engineering student at the University of Evansville and we build a Formula style racecar which uses a 600cc Honda RR engine. I know it's not a VFR but I have one and it's the same concept. I do the Engine Management for our team (we use an aftermarket ECU).
    I have not really looked into this product, but can safely bet that it won't do a damn thing. Here is how fuel injection works in a nutshell, sorry if you already know this.....
    1. The injectors deliver a varying amount of fuel based on rpm and engine load. This is controlled by how long they stay open. Therefore every time they open they are squirting the same amount of fuel with the varying factor being how long they stay open. This is in the range of 1.6 to 15 msec of "open time" or pulse width.

    2. For this to work properly your fuel pressure has to stay constant (typically 50 psi on these bikes). I am not sure if on the VFR the regulator is on the pump in the tank or on the fuel rail like the Honda F4i (RR in tank). I would bet it is on the rail if it is easily changeable.

    Conclusion: I am not sure how a different fuel pressure regulator would help. A different regulator without ECU remapping would just cause the engine to run rich or lean depending on a higher or lower pressure, respectively.
    I would say this is a huge gimmick, but I have been wrong many times in my life!
     
  3. okiengr

    okiengr New Member

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    I have heard it go both ways. People with 5th gens seem to notice a good difference in the way the bike pulls in the lower RPM range, but 6th gen bikes don't seem to make a difference with from what I've heard and read.
     
  4. seadooloo

    seadooloo New Member

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    If you are looking for a relatively cheap fix for fueling issues on 6 gen, The modified FPR does work. Along of course with a good starter valve synch. (I only say this because the instructions recommend doing a SVS when installing the FPR and I did, and the combination of the 2 made my bike run very noticably better all around)
    My 6 gen has one on it and it runs way better than it used to with the stock FPR on it. Many others have used it also with good results. I recommend it, whether scientifically it should work or not, it does.

    by the way, the FPR worked really well for eliminating the 4,500-5,000 RPM flat spot when accellerating slowly through that rpm range
     
    Last edited: Nov 15, 2006
  5. im944

    im944 New Member

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    I guess I stand corrected. Does anyone actually know how this works? The only thing I can think of is that maybe the vacuum hose that runs from the intake to the regulator that tries to compensate for quick throttle changes is different. Well, not the hose itself but the spring inside the regulator acts differently.
    If this is such a major problem with such an easy fix I would have thought that Honda would have caught this in their engine development stages.
     
  6. jambman

    jambman New Member

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    I have read about all the advantages of the modified FPR. I bought one from Turbo City and am in the process of changing it on my 2000 VFR.
    Easier said than done.....does anyone have experience with this? The instructions don't address the problem of the FPR hitting the starter valve lever when unscrewed. It would appear that the throttle body needs to come of just to get to the FPR.....Am I missing something? While I would like the FPR installed, I don't like to go through that much engine disassembly to get r' done.
    Thanks
     
  7. seadooloo

    seadooloo New Member

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    Sorry, not any input here on a 5th gen. It was very simple on the 6th gen though, and, of course, it figures it wouldn't be as easy on the previous generation. Hopefully someone with some 5th gen experience will chime in and guide you through it the easy way.

    I just went on VFRDiscussion and saw that a few people have done the mod on their 5th gens. One guy just bent the tube a little, to be able to get it in and out without doing anything to lift the fuel rail for better access. Log on and do a search for either TCFPR or FPR. Good luck, I think this mod is worth the trouble.
     
  8. fastrc46

    fastrc46 New Member

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    I had the same trouble with mine. Loosen / remove the bolts that mount the starter valve bracket. You can move it out of the way just enough to get the FPR to spin into place. Yeah. It's a pain. But it can be done with throttle body in place.
     
  9. Scott_Lilliott

    Scott_Lilliott New Member

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    I installed an FPR on my 01 last winter - a major PIA to remove and install on the 5G. I had to loosen the 2 ? screws on the starter valve mount, and remove the 3 screws on the auto-choke valve on top to lift the whole thing out of the way to spin off and spin on the FPRs. The stock FP rating is 36 psi, the new one is 42-44 psi. It most certainly eliminated the off-on glitch and slightly fattened the whole mid-range. I still need to do another starter valve synch. At the same time, I swapped in a BMC air filter - gives the intake a nice growl!

    Coming up next: The F4i front end!
     
  10. veefer800canuck

    veefer800canuck New Member

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    Got one on my '99. Works as advertised. Definetly richened up the bike. Can smell it in the exhaust. (unscientific I know)

    Still getting about 44 MPG (imperial) and the bike really pulls better in the lower rev ranges. On/Off throttle response is better.

    Why didn't Honda do it? Emissions, that's why.
     
  11. jambman

    jambman New Member

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    Thanks Fastrc46, I'll give that a try tonite. I can see bending the vacuum port a bit, but not the fuel port!
     
  12. jambman

    jambman New Member

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    Scott,
    Followed your instructions and it worked fine.

    Thanks!!!!
     
  13. jambman

    jambman New Member

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    Okay everyone, gather around and listen to my story. We were blessed with an extraordinary 60 degree day yesterday and I could wait no longer to test the results of the FPR change on the Fifth Generation.
    All I can say is wow! 15,000 miles, all stock and this change totaly eliminated the low speed throttle application "snatchiness" Power delivery is smooth and linear all the way up the rev range. Can definetly smell that it is running richer, but drivability is greatly improved. If I notice any significant change in either gas milage (it will have to be significant) or decreased plug life I will consider a re-map......otherwise, I recomend the device!
     
  14. Spike

    Spike New Member

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    Have any of you combined the FPR with a PowerCommander?
    Spike
     
  15. jambman

    jambman New Member

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    No power commander. Totaly stock other than the FPR. I'm not up on the technical side enough to know what more improvement could be made. I don't plan to change the exhaust.
     
  16. Scott_Lilliott

    Scott_Lilliott New Member

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    No PC here either, tho' I do have a Techlusion-in-waiting. The last dyno I did with the new FPR showed some changes in the O2 readings, but the Techlusion doesn't allow for leaning the mixture. Right now it runs great.

    Scott
     
  17. nasadiver

    nasadiver New Member

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    Power Commander & FPR Combo

    I just did the combo. I installed the FPR first, along with a K&N Air Filter, O2 Elims, and synced my starter valves. I already had Staintunes installed. Made a HUGE difference all combined.

    VERY smooth power delivery all the way through the RPM range. Silky smooth VTEC transition.

    I put the PCIII-USB on and it ran a little worse with the default Staintune map downloaded from DynoJet. Jerky in spots. Some sudden surges and rapid drops in power on some decels. The map from DynoJet was VERY rich in spots.

    I was able to hook up a map from "cozye" over at VFRDiscussion.com that he had modded and now the bike runs great again. Absolutely no "feel" of VTEC transition, up or down - smooth, smooth, smooth. The only indication is the sound change. Bike runs very strong.

    The mileage is a little worse with the PC in verses running just the FPR, but my thoughts are that once I have the money to get a custom map professionally done at a Dyno center ($200), I can gut my CAT right before and the map will correct for that as well. For an additional $50, I can get a second map that leans more towards the economy/commuting side of the performace scale. The power delivery will still be smooth and linear, it will just be a little leaner to conserve some fuel.

    This way I can load the "play" map when I know I'm heading to the hills and load the "gas" map when I know I'm going to go to earn money to pay for more rides to the hills. :smile:

    Hope this helps.
     
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