New to VFR and have throttle/VTEC Issue

Discussion in '6th Generation 2002-2013' started by donkovac, Jul 19, 2009.

  1. donkovac

    donkovac New Member

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    I just bought an '05 VFR ABS a couple of months ago and took it for my first long ride in the mountains of WV last week. I came off of a 1200 ZRX and so far I am very impressed with the VFR's smoothness and sophistication.

    I do have an issue with abrupt throttle response in the 7k RPM range when the VTEC kicks on and off. I have heard of this problem before I bought the bike so I was sensitive to the issue. I am surprised at how abrupt it actually is, and even though I got used to it after a while, it sometimes seemed to jerk so hard that I was afraid of stability issues going around curves.

    I am sure that this issue has been discussed extensively here so if someone could please direct me to some information as to how to correct this with aftermarket parts or mods I would be greatly appreciative.

    Thanks
     
  2. TOE CUTTER

    TOE CUTTER Mullet Man

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    V-tec

    Power Commander will help and does smooth out the snatch at off idle throttle openings. I had a big problem with it but after a few thousand miles I don't notice it.
     
  3. bitterpil

    bitterpil New Member

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    Kinda like the old turbos. More like a 4Bbl Carb . womp -wawwwww...
    You are getting 2 more sets of valves at that stage in the game. You can work it out or learn to dig it.
     
  4. Michael D

    Michael D New Member

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    I bought my bike with the Power Commander. The original owner had dynoed it, and for the most part under medium throttle there is no abruptness. The only time it happens is when I have the throttle wide open, and than you're looking forward to the rush!
     
  5. ace57

    ace57 New Member

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    Its weird, my '07, which I bought used with 6300 miles on it, is not abrupt at all with the vtec kick-in, and the bike is stock.... its pretty mild actually.

    Wonder why it seems that some are more intense than others?:rolleyes:

    ace57
     
  6. Spectre

    Spectre New Member

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    The V4 engine performs optimally at higher rpm's, and VTech will kick-in when the tachometer rises above ~6400 RPM's. As the additional valves open up during this VTech transition, there is a very slight lag immediately followed by a moderate surge in power. At the same time, the V4's signature sound goes from growling, to snarling and then roaring as the engine goes into 'afterburner' mode and you continue to really get on the throttle. The motorcycle is then going ballistic. :biggrin:

    My '07 VFR 800A's engine is unmodified, and I'm among those who enjoy the sensation of the VTech transition. That said, here are some examples of how to better understand and manage VTech:

    1) Situation #1: Fast takeoff from a full stop. Suppose you're at a stop sign on a long and straight stretch of rural road that is in fine condition. As you release the clutch and roll-on the throttle in 1st gear, assertively and smoothly wind-out the engine and as you rapidly pass ~6400 rpm you will feel VTech kick-in. Continue to smoothly roll-on the throttle and once the rpm's are well above 8000-10,000, smoothly and quickly upshift into 2nd gear, keep applying throttle, and then do the same with 3rd and higher gears while keeping the rev's high.

    The point in this example is that once you've raised the rpm's way above the VTech transition at 6400 in 1st gear (let's say 9000) all of the valves are now open, and as you rapidly step through the higher gears while getting on the throttle, the rpm's will remain high enough that even when the engine grunts down a little (and the rpm's momentarily dip a little) when shifting into the next gear, there will be no further power surges from VTech since you opened the extra valves before you ever left 1st gear, and in this example the goal is to keep them OPEN as you continue to accelerate and upshift.

    On the other hand, if you were to try a fast takeoff in which you shift from 1st to 2nd and higher gears by revving the engine just a wee bit past 6400, and you then upshift, the rpm's will likely dip well below 6400 as the engine grunts down and lugs a little on the next highest gear. What happens then? You guessed it-- you will likely experience successive VTech surges each time the rpm's go above 6400. Keep the revs up.

    2) Situation #2: Riding very twisting and hilly/mountainous (i.e., treacherous) roads at a safe and controlled pace. For average street riders such as myself who just wanna ride such roads safely and conservatively without quickly getting into trouble in the curves (particularly blind curves) by suddenly finding one's self going too fast, I find that in many situations it's often best to keep the revs up (not necessarily over 6400), while remaining in the lowest gear that provides a good margin of engine braking as well as to avoid going too fast, something that higher gears often tend to invite among less skilled riders such as myself.

    Such roads may also include occasional stretches such as straightaways as well as more gentle curves which may briefly seduce a rider into briefly going faster. At any rate, it seems to me that when entering and traversing turns and curves, with the motorcycle leaned over, this is not when you'd want to lose track of your rpm's and then suddenly have VTech kicking in with it's brief lag followed by a surge as you roll-on the throttle past the 6400 rpm transition zone. It's like you either enter curves with the rpm's either well above or below the transition point, while correctly shifting, rather than hovering the rpm's near the transition point during the early and mid portions of curves, which could put you at risk for an unpleasant surprise from VTech.

    3) Situation #3: Swiftly and safely passing slower traffic. Let's say that you're comfortably cruising along at 75 mph in 6th gear, at 5000 rpm's on a 2-lane freeway, and you're in the right-hand lane, minding your own business when a cager begins creeping up behind you in the left lane, and instead of passing you, she just sits there and obliviously loiters about 2-3 car lengths behind you while she's talking on her cell phone and looking into the vanity mirror applying makeup, etc.. Meanwhile, you soon see that you're about to get boxed in because you're approaching a slower moving truck in front of you in your lane...

    You decide that you wanna shoot the fast closing gap by first blinking your left turn-signal along with 2-3 quick leftward head-checks before you would then swiftly and safely pull out into the left-hand lane, pass, and tuck back into the right-hand lane. At this point, let's further suppose that you've downshifted from 6th to 5th in response to this scenario as you're about to get boxed in, and the engine is now spinning at 5500 rpm's, but in order to really dart around and get out of the way, you need a really quick burst of speed, and here is where VTech's "surge" can be a good friend. Need to pass really quickly from a higher gear with the 800cc V4 engine? Try downshifting at least two gears rather than just one, keep the revs high, and you will be as fast as greased lightning.

    4) Listen to the sound of, and feel the cadence of the engine in the seat of your pants. Even while wearing earplugs and a quiet helmet (which should be a routine practice) once you get to know the VFR 800 it's often less necessary to always glance at the tachometer in order to get a good sense for how fast the engine is spinning, and how close you may be to the VTech transition point.
     
  7. donkovac

    donkovac New Member

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    That's a lot of good information.

    Unfortunately, the twisties is where I like to be and that unpleasant VTEC kick when negotiating a curve is exactly what is bothering me!

    I guess I need to ride it some more to see if I can compensate for it. But right now it seems like an uneccesary, and somewhat scary, situation for me to be going around a curve and being afraid to pass through that part of the rev range.

    The abrubt transition seemed to be more prominent at times, so I'm sure I can learn to finess it with some practice.

    Looks like the best suggestion thus far is to get a power commander....
     
  8. speedpoker

    speedpoker New Member

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    Yes pick up a power commander. I have seen them around for $150 used lately. It will make a big difference. I can go in and out of the vtech in corners and it is not a problem at all. I slapped a power commander on right away so I do not really remember the bike before that well but I know the vtech transition was a lot more harsh. I even have the older power commander non usb that cuts half of the map off but it still works great. I would get one of those if you could find a great deal also.
     
  9. monk69

    monk69 New Member

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    It took me a little time to get use to it, but I don't even notice it any more. Time may vary....
     
  10. speedpoker

    speedpoker New Member

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    Yes even without the power commander I did not feel the thing was a crazy transition or anything like that and I am sure I would have gotten used to it and been happy with it. I was happy with it but was more happy when the power commander smoothed it out a bit.
     
  11. stewartj239

    stewartj239 Member

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    My stock 2007 is butter smooth. I believe that Honda changed the VTEC transition in 2006.
     
  12. SwiftTech

    SwiftTech New Member

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    I came from a 600RR to the VFR. I have noticed that the Vtech transition is no more violent then the 2nd stage fuel injectors coming in at 8000rpm on the 600RR. The only aftermarket goodies on my bike are Leo Vince slip on's and a K&N filter.
     
  13. 02 VFR Rider

    02 VFR Rider New Member

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    try going into corners in a higher gear w/ tach around 5,000 rpm.
     
  14. Action

    Action New Member

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    donkovac,
    I have noticed that people living in hot and humid climates seem to have more complaints about a harsh VTEC transition. Besides getting a power commander (if you are going to get one go for the V not the III), you could try disconnecting the 02 sensors. That alone seems to help some people. If you use Radio Shack resistors it costs a whole dollar and is completely reversible. Others have had good luck using a high pressure fuel regulator. If you do a search there is lots of info on both subjects. Good luck.

    Action
     
  15. donkovac

    donkovac New Member

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    Thanks, these are good tips.

    Anyone know where to get the best deal on a powercommander V? What's the main difference between a PC III and a PCV?

    Also, are there any drawbacks to installing a Powercommander that I should be aware of?

    Thanks
     
  16. warnabrother

    warnabrother New Member

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    I love the transition.. one of the highlights of the bike IMO.. much like my old WRX's turbo lag..
    and the sound of the Staintunes barking give me a smile EVERYTIME
     
  17. VIFFER RIDER

    VIFFER RIDER New Member

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    That's because you have a 07, 06+ models have a different VTEC mapping that transitions smoother then earlier gen models. My 02 Vtec feels pretty abrupt in lower gears (like 1 or 2nd gear WOT) but hardly feel anything in any other gear. I learned to just keep the RPM above the VTEC kick-in threshold while canyon carving and you will do ok.
     
  18. MrBlackVFR'06

    MrBlackVFR'06 New Member

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    I have also found throttle position dictates how hard VTEC kicks. The harder you have it wound on, the harder VTEC actuation. And my bike is a 12'06, so has the revised transfer point. 20,000km's on the clock. My first post too. Hello everyone.
     
  19. CBR600F4i

    CBR600F4i New Member

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    This is a direct quote from the 2006 Honda press release:

    "For 2006, the VFR’s high-performance V4 VTEC system has been fine tuned for
    smoother and more effective shifting between its 2-valve and 4-valve operating zones.
    During hard acceleration, the physical jolt of the engine when coming onto full 4-valve
    operation has been reduced for a more natural feeling of surging performance, while the
    sound of its characteristic leap in response continues to excite. The engine speed shift
    zone has also been reduced from 6,800rpm to 6,600rpm, for more comfortable access to
    the VFR’s full 4-valve performance.
    This lowering of the shift zone was specifically targeted at equalising the power
    and torque outputs for both 2-valve and 4-valve operation, and selecting the crossover
    engine speed of these two power curves as the new shift point. The result is a much
    smoother transition from 2-valve to 4-valve operation for seamless acceleration that still
    takes full advantage of the best power characteristics of the two distinct operating
    configurations.
    Not only has the valve shift zone been lowered slightly in the rev range for more
    comfortable engagement, the speed at which its valve actuation reverts to 2-valve
    operation has also be lowered to 6,100rpm for a wider range of engagement that helps
    minimise any potential for cogging between the two zones of operation.
    In conjunction with this modification to the engine’s V4 VTEC valve actuation
    system, the PGM-FI fuel injection system’s ECU and injectors (taken directly from the
    CBR1000RR Fireblade) were also modified to achieve improvements in driveability
    while further enhancing the VFR’s sporty feel. One other result of this fine tuning of the
    fuel injection system is that fuel consumption also sees a small but significant
    improvement."

    My 2004 was pretty bad. It's not so much the VTEC transition that bothered me, it was the big power dip right before, and the cruise surging. I tried all the suggestions; O2 delete, PAIR delete, fuel pressure, etc., none made a significant difference. The power commander III did make a big difference, probably 90% problem solved, but still had some cruise issues that are difficult to tune out. So this winter after reading that press release info I decided to swap to an '06+ ECU. The new ECU has different connectors, so the harness needs to be changed as well. It's like a completely different bike now. I still have O2 delete and I'm running 42 psi fuel pressure, but I sold the power commander and it runs better than ever.
     
  20. Alaskan

    Alaskan Member

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    An old post revived, but what the heck. A Power Commander and a good tuner will completely eliminate the drop in HP and torque immediately before VTEC transition. Completely. It will also grealy reduce the stock setup's snatchiness at small throttle openings - which I found much more annoying than the VTEC transition.
     
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