VFR VTEC Must Read Throttle Problems - Page 3
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Thread: VFR VTEC Must Read Throttle Problems

  1. #31
    steve tech
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    I have not gone in to it yet but a simpler way maybe is to remove the road speed signal at the engine ecu. I have only got the wiring diagram for the non abs model (mines abs) however it looks like the speed signal is hard wired to the speedo, engine ecu and abs cu separately (no can bus) if this is the case it would be easier enough to try. I wouldnt think it would set a fault because it is a normal situation (bike at standstill). If Honda use fuel shut off, that would explain the issue of the sharp turn while moving irritating throttle snatch I get.
    Twice on my commute going downhill braking and turning right quite sharply. Also the irritating snatchy throttle going over bumps on decel.
    First things first though I have to find if they use throttle shut off!
    By the way, looking at the way the idle increases with the pair connected it shows that the pair system is actually helping to overcome the back pressure of the cat/exhaust system and speed the exhaust gas's out.

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  3. #32
    steve tech
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    http://www.youtube.com/watch?v=yVqQnRrvask

    Lots of engine decel here!! No jerkyness, maybe we are NOT Freddy Spencer!!

  4. #33
    Registered User Array Chumly's Avatar
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    Go Freddy!

    Assuming the road speed signal can be deleted from the engine ECU without causing problems, why would stopping this signal would stop fuel shut-off? I would have thought RPM and TPS are the two variables needed for fuel-shut off.

    With the FZ1 RPM @ 4,500 and over plus closed TPS signal enables fuel-shut off. I don’t think road speed signal is part of fuel shut-off logic, but I could be wrong. BTW Ivan’s FZ1 Fuel Cut-off Eliminator is a small tube with 6 wires.

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  6. #34
    steve tech
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    Quote Originally Posted by Chumly View Post
    Go Freddy!

    Assuming the road speed signal can be deleted from the engine ECU without causing problems, why would stopping this signal would stop fuel shut-off? I would have thought RPM and TPS are the two variables needed for fuel-shut off.

    With the FZ1 RPM @ 4,500 and over plus closed TPS signal enables fuel-shut off. I don’t think road speed signal is part of fuel shut-off logic, but I could be wrong. BTW Ivan’s FZ1 Fuel Cut-off Eliminator is a small tube with 6 wires.
    I don't know about Honda but BMW only cuts fuel with a road speed signal.
    Anyway the main thing is my VFR is awesome now the starter valves are synced. I rode for 5 hours last Sunday (actually came out your way).
    The bike runs great with no snatch at any time, I rode to work today in traffic and it's a different beast!
    As I said I synced them with the pair working also making sure that as I opened up the throttle all cyls where pulling the same. I also adjusted the chain. I am running the idle at 1500 with the pair connected.
    If I had adjusted them with the pair blocked off as in the book then when it's connected back they would have been a mile out! Try it you will see how far out they are. With the manometer connected set them with your thumb over the pair hose (air cleaner connector) then remove your thumb, the revs will increase and the gauges will be way out!

  7. #35
    Still defying gravity... Array Thumper 8's Avatar
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    Quote Originally Posted by steve tech
    Anyway the main thing is my VFR is awesome now the starter valves are synced. I rode for 5 hours last Sunday (actually came out your way).
    The bike runs great with no snatch at any time, I rode to work today in traffic and it's a different beast!
    Hmmm, I think both your bikes are essentially stock - except for the fiddling and adjustments noted in this thread. I am fortunate but I have never had any noticeable lag, no real flat spot around 5,000 to 6,000 rpm and always a very smooth VTEC transition. All I have done, besides basic maintenance, is tighten my throttle cable a couple of times to remove any annoying slack and put on Remus CF pipes (cat back set up) which seems to give the bike a little extra mid-range oomph - strictly seat of the pants impression though. Now you have got me wondering if I can make a good bike even better... or should I stick with the old 'if it ain't broke don't fix it' philosophy? I have ridden one other 6th gen VFR and it seemed a little 'jerkier' than mine - a little harder to ride smoothly and it seemed to have a slower throttle response, but all this talk of improving an already great bike has got me wondering. One day I may want to hook up with you guys and compare notes - and see if it is worth fiddling with the bike to get even better performance.
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  8. #36
    Registered User Array Chumly's Avatar
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    Hi-yah Steve,
    The VFR engine management system is nowhere near as sophisticated as modern autos, Honda’s system would be much more akin to the FZ1 (minus VTEC of course), that’s pretty bare-bones-basic by auto standards. I'm taking a decent guess that if the FZ1 ECU needs RPM data for fuel cut-off, so would the VFR's ECU.

    The last time I synced the SV’s was two years ago and I did get them nice and even at idle, but I seem to recall they did not run even off idle. Maybe I should try and sync the SV’s with PAIR enabled and off idle too.

    Did you try syncing the SV’s with PAIR disabled as per the manual to see if it made things better or worse?

    I have confirmed that the SV’s can go out of sync easily and it takes many km's before they “settle down”.

    Hey Thumps,
    You might be a happier rider by following these suggestions, shops don’t do this kind of stuff with a routine service. For me this is the first bike engine I was not real happy with out-of-the-box, and I don’t breathe on gear unless it bugs me. Like Steve pointed out, Bike mag agrees about the VFR being wacky.

    Colbert Report's on, gotta go!

  9. #37
    Registered User Array J1k's Avatar
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    kinda off the topic but has anyone had issues with valves being out of adjustment?iam curious as i work on these things alot and have run into many that are out.i keep hearing that they rarely go out but iam finding alot are tight and its always on the 05/06's.

  10. #38
    Registered User Array Chumly's Avatar
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    I’ve heard the same things as you that they hold their clearances well. How exactly are you checking them; I am sure you know getting the correct “feel” can be rather subjective.

  11. #39
    Still defying gravity... Array Thumper 8's Avatar
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    Quote Originally Posted by J1k View Post
    kinda off the topic but has anyone had issues with valves being out of adjustment?iam curious as i work on these things alot and have run into many that are out.i keep hearing that they rarely go out but iam finding alot are tight and its always on the 05/06's.
    My '02 has 53,000 kms now - I have had two valve inspections done - both times no adjustment needed.
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  12. #40
    steve tech
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    Quote Originally Posted by Thumper 8 View Post
    Hmmm, I think both your bikes are essentially stock - except for the fiddling and adjustments noted in this thread. I am fortunate but I have never had any noticeable lag, no real flat spot around 5,000 to 6,000 rpm and always a very smooth VTEC transition. All I have done, besides basic maintenance, is tighten my throttle cable a couple of times to remove any annoying slack and put on Remus CF pipes (cat back set up) which seems to give the bike a little extra mid-range oomph - strictly seat of the pants impression though. Now you have got me wondering if I can make a good bike even better... or should I stick with the old 'if it ain't broke don't fix it' philosophy? I have ridden one other 6th gen VFR and it seemed a little 'jerkier' than mine - a little harder to ride smoothly and it seemed to have a slower throttle response, but all this talk of improving an already great bike has got me wondering. One day I may want to hook up with you guys and compare notes - and see if it is worth fiddling with the bike to get even better performance.
    Hi, I'm the kind of guy that thinks if its not broken don't fix it!!
    I got involved in this because like Dan this is the first bike that Ive owned that I thought was a pain to ride around town.
    I think it depends on your mechanical ability, if you really understand how it works and what your doing then go for it. If not you may end up with it being worse.

  13. #41
    steve tech
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    [QUOTE=Chumly;972483]Hi-yah Steve,
    The VFR engine management system is nowhere near as sophisticated as modern autos, Honda’s system would be much more akin to the FZ1 (minus VTEC of course), that’s pretty bare-bones-basic by auto standards. I'm taking a decent guess that if the FZ1 ECU needs RPM data for fuel cut-off, so would the VFR's ECU.

    The last time I synced the SV’s was two years ago and I did get them nice and even at idle, but I seem to recall they did not run even off idle. Maybe I should try and sync the SV’s with PAIR enabled and off idle too.

    Did you try syncing the SV’s with PAIR disabled as per the manual to see if it made things better or worse?

    I have confirmed that the SV’s can go out of sync easily and it takes many km's before they “settle down”.

    No I did not ride the bike with the pair disabled and the starter valves synced. It makes no sense.
    First the book tells you to set the RPM to 1200. Then it says block off the pair and sync them. All ok but now if you unblock the pair the RPM's rise to about 1500 and the valves are no longer in sync. So the book says bring the idle back now to 1200. If you do that the valves are way out of sync.
    I tied that and thought this is stupid they want you to run with the pair system on so why not just sync them with the pair on, now you can adjust the idle to what you like, balance the starter valves and you know when you put it back together exactly what idle speed you will end up with, if you need to adjust the idle with it all together the balance will be out. Try it, adjust the starter valves and the change the idle and they will go out. What I am saying is the idle you have before putting it together is the idle you want to end up with, if you change it the balance will be out. Blip the throttle a few times and keep fine tuning and you can get them dam close.
    I think thats why when guys have synced the starter valves (the "Honda" way) they are saying it runs great when they block off the pair! It will because the valves have been synced without the pair in the first place so now they are in sync again.

  14. #42
    clempot911
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    This is great information.
    I don't remember my bike doing this when new but I believe it has been getting progressively worse since then. I took out my '04 for the first time this season and it was really acting up. It's never been smooth @ low RPM's but what really gets me is the surge/hesitation at steady throttle somewhere between 4-5.5K. I would hold the throttle dead steady at these RPMs and within a few seconds it's as if the bike would start to decelerate on it's own (at least a few hundred RPMs) - you first feel it happening by seat-of-the-pants then verify it by looking at the tach & speedometer. If I then apply VERY, very slight throttle it's almost as if I feel it bog a bit - as if the plugs are loading up/fouling. At some point the bike figures out I'm adding throttle and it just snatches forward. Never a problem above 6K. Also, I do run o2 eliminators.

    I'm going to do the SV sometime in the next week or so to see if that makes a difference, but I have a few questions/comments:

    1) The bike doesn't always act this way - sometimes it seems fine, and at other times it acts up. Doesn't it seem that if the SV settings are at fault this problem would always be there?

    2) The only other things that rank high on my list of probable causes for this surge/hesitation would be the TPS and MAP sensors. If the ECU thinks the throttle is being moved when it's not you are likely to see RPM changes. And if you open the throttle and the ECU doesn't see it that would also cause a problem.

  15. #43
    steve tech
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    Quote Originally Posted by clempot911 View Post
    This is great information.
    I don't remember my bike doing this when new but I believe it has been getting progressively worse since then. I took out my '04 for the first time this season and it was really acting up. It's never been smooth @ low RPM's but what really gets me is the surge/hesitation at steady throttle somewhere between 4-5.5K. I would hold the throttle dead steady at these RPMs and within a few seconds it's as if the bike would start to decelerate on it's own (at least a few hundred RPMs) - you first feel it happening by seat-of-the-pants then verify it by looking at the tach & speedometer. If I then apply VERY, very slight throttle it's almost as if I feel it bog a bit - as if the plugs are loading up/fouling. At some point the bike figures out I'm adding throttle and it just snatches forward. Never a problem above 6K. Also, I do run o2 eliminators.

    I'm going to do the SV sometime in the next week or so to see if that makes a difference, but I have a few questions/comments:

    1) The bike doesn't always act this way - sometimes it seems fine, and at other times it acts up. Doesn't it seem that if the SV settings are at fault this problem would always be there?

    2) The only other things that rank high on my list of probable causes for this surge/hesitation would be the TPS and MAP sensors. If the ECU thinks the throttle is being moved when it's not you are likely to see RPM changes. And if you open the throttle and the ECU doesn't see it that would also cause a problem.

    You would have to determine if you feel that it is a starter valve issue.
    The starter valves are used at slight throttle openings and at idle. Basically they are used as a progression to smooth out idle to throttle transition.
    If you are going along with the throttle off or just cracked slightly open at 4000rpm for example braking for a turn closed throttle then getting on the gas when this occurs it could be the SV's. However if you have the throttle more than 15% to 20% open I doubt setting up the SV's wil help.
    A map sensor or TP sensor problem will trigger the FI light and you would get a code.

  16. #44
    Registered User Array Chumly's Avatar
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    It has been argued that the resistor in the O2 sensor may change its fundamental resistance due to changes in ambient operating temperature and thus when the ECU is in closed loop mode (you refer to it as “steady throttle somewhere between 4-5.5K”) there could be changes in the F/A ratio as this resistance changes. I’m not so sure of the merit of this argument, but if I was I might be inclined to replace the resistors in the O2 elims with precision pieces, it would be cheap and easy insurance.

    Do you have the Dynojet O2 eliminators? If so (and in fact even if you do not) I would run out a buy a can of Caig DeoxIT http://www.caig.com/ and pull apart and spray every electrical connector you can get your hands on from the multi pin ECU connector on down to the lowly battery terminals and grounds and O2 eliminator connectors and high/low tension ignition connections. I would also give some thought to a new battery.

    The VFR is prone to electrical gremlins which are noted on the VFRD website. I have not had any, but then it might be because of my use of Caig DeoxIT and a replacement battery.

    I can't comment on steve tech's views so I’m not 100% sure if all MAP sensor / TP sensor issues always trigger the FI light and have a code but he's a pretty smart cookie, in any case get the shop manual as it should list what faults it recognizes.

    I have to say though, that if it's not an electrical gremlin problem that might be addressed with Caig DeoxIT or by reviewing the electrical problems as noted on the VFRD website, it does appear to be happening only in what would normally be the closed loop lean burn mode, and that leaves a few more options:

    1) Switch to Chevron only. Techron is your friend, get some bottles of the stuff as I have done.

    2) Get a PCIII and adjust out the leanness at the throttle and RPM settings in question as I have done.
    Last edited by Chumly; 04-03-2007 at 10:26 PM.

  17. #45
    clempot911
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    Quote Originally Posted by steve tech View Post
    However if you have the throttle more than 15% to 20% open I doubt setting up the SV's wil help.
    A map sensor or TP sensor problem will trigger the FI light and you would get a code.
    Steve - I was cruising at a steady speed in a high gear - probably less than 20% throttle, but I have read elsewhere that SV valves have no effect above as little as 4% throttle. I think it's still worth doing them. Yes, the sensors would set a fault code, but probably not if they are still within the expected range.

    Quote Originally Posted by Chumly View Post
    It has been argued that the resistor in the O2 sensor may change its fundamental resistance due to changes in ambient operating temperature and thus when the ECU is in closed loop mode (you refer to it as “steady throttle somewhere between 4-5.5K”) there could be changes in the F/A ratio as this resistance changes.
    I never measured the resistance, but that is easy enough to do. I guess I can carry a can of 'circuit freeze' and spray them when it starts acting up.......wouldn't be the first time I use that trick.

    Quote Originally Posted by Chumly View Post
    Do you have the Dynojet O2 eliminators? If so (and in fact even if you do not) I would run out a buy a can of Caig DeoxIT http://www.caig.com/ and pull apart and spray every electrical connector you can get your hands on from the multi pin ECU connector on down to the lowly battery terminals and grounds and O2 eliminator connectors and high/low tension ignition connections. I would also give some thought to a new battery.
    Yes, DynoJet parts. That's my next step when I do the SVs - disconnect and spray each connector down. Should I apply dielectric grease also? A questionable ground or some resistance in one of the sensor connections to the ECU would certainly explain the odd behavior.

    Quote Originally Posted by Chumly View Post
    I can't comment on steve tech's views so I’m not 100% sure if all MAP sensor / TP sensor issues always trigger the FI light and have a code but he's a pretty smart cookie, in any case get the shop manual as it should list what faults it recognizes.
    I bought the shop manual when I bought the bike (I do that for all my bikes - just to know what I'm getting into). I still think that if the values reported by the sensors are within range they will probably not set a fault code. If the ECU sees a short or an open - yes.

    Quote Originally Posted by Chumly View Post
    1) Switch to Chevron only. Techron is your friend, get some bottles of the stuff as I have done.

    2) Get a PCIII and adjust out the leanness at the throttle and RPM settings in question as I have done.
    Techron is my friend! I'll run some through there just because it's good preventative maintenance. As for the PCIII,
    I hope I don't have to go that route. From what I understand you really should have a custom map made when you get one, so I'll be dumping another $600 into this.

    Would you believe all my carb'd bikes never had any of these problems? I thought FI would be a lot smoother, but that's not been the case.

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