VFR VTEC Must Read Throttle Problems - Page 2
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Thread: VFR VTEC Must Read Throttle Problems

  1. #16
    Registered User Array Chumly's Avatar
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    Quote Originally Posted by nutcracker
    I red that article about a month ago , very interesting . This is my first fuel injected bike so I'm not really sure how it's suppose to respond at steady slow speed but I think that it does act kinda weird. I would really like to compare to another VFR,
    PM me and we'll see

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  3. #17
    Registered User Array Chumly's Avatar
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    I had a nice chat with Jeff at Honda Canada (I asked the same question this time last year). I was told that the Honda Canada Technicianís official position is that they recognize that there are certain "characteristics" that the motor may have, such as the VTEC engagement, off idle sharpness, and steady throttle surge but that these "characteristics" are "normal" for the bike, and they have no plans at this time to do anything about, but that the Honda Canada Technicianís have logged my concerns and that they have received other logged input from other owners with similar concerns.

    Jeff at Honda Canada said he very much doubted that there is anything wrong with any of the ECUís. He went on to say much the same as last year; that Honda is meeting very tight future emission standards, while producing very high performance engines, and that it is a difficult balancing act.

    Jeff did say that the use of premium gas in Canada has an additive that can coat the 02 sensors and make them lazy or ineffective, and that may be a cause for some problems. I told him that the 02 sensors only contribute in the limited conditions of steady state closed loop cruising, so as to lean out the mixture, and that ineffective 02 sensors would not affect performance under constantly changing throttle inputs as the EFI does not go into closed loop unless it is steady state throttle.

    If you wish to communicate with Jeff to log your concerns he can be reached:
    Honda Auto, M/C, P/E & Marine Customer Relations
    Jeff (3393) 1 888 946 6329

  4. #18
    steve tech
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    You can read my research into this subject and what I did here -:

    http://www.vfrdiscussion.com/forum/i...howtopic=30237

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  6. #19
    Registered User Array Chumly's Avatar
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    Quote Originally Posted by steve tech View Post
    You can read my research into this subject and what I did here -:

    http://www.vfrdiscussion.com/forum/i...howtopic=30237
    I have a PC III and O2 elims and did a really precise SV sync as well as remove all slack from the throttle cables. My bike is better but does not equal the linear throttle of many other bikes.

    From what I can tell you are saying that removing PAIR will have no effect if O2 elims are in place. Perhaps that’s why I never notified any improvement when I disabled PAIR, so I left PAIR enabled but…….are you aware that the O2 sensors do absolutely nothing most of the time, and only come into effect during closed loop, steady state, steady throttle cruising operation and not at other times? The O2 sensors on the VTEC do not act as they do in a modern auto engine where they are relied on much more often. Also the VFR ECU is not a “learning” ECU.

    I get the impression from your posts on VFRD that you might believe the O2 sensors are enabled (i.e. closed loop) much more often than is the case (as is the case with modern auto engines.
    Last edited by Chumly; 03-17-2007 at 04:34 PM.

  7. #20
    steve tech
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    Quote Originally Posted by Chumly View Post
    I have a PC III and O2 elims and did a really precise SV sync as well as remove all slack from the throttle cables. My bike is better but does not equal the linear throttle of many other bikes.

    From what I can tell you are saying that removing PAIR will have no effect if O2 elims are in place. Perhaps thatís why I never notified any improvement when I disabled PAIR, so I left PAIR enabled butÖÖ.are you aware that the O2 sensors do absolutely nothing most of the time, and only come into effect during closed loop, steady state, steady throttle cruising operation and not at other times? The O2 sensors on the VTEC do not act as they do in a modern auto engine where they are relied on much more often. Also the VFR ECU is not a ďlearningĒ ECU.

    I get the impression from your posts on VFRD that you might believe the O2 sensors are enabled (i.e. closed loop) much more often than is the case (as is the case with modern auto engines.

    First let me say Hi and thanks for the reply.
    A little bit about myself, I have been a tech, working for BMW (cars) for the past 35 years. I have owned this 05 VFR for just over a year This year I got to thinking that I should be able to get the thing to be a bit more smooth on take off than it is. It is awesome on the highway etc but it really is hard work around town. Anyway this is why I am experimenting and asking questions.
    I was not aware that the o2 sensors only work in closed loop at certain times.
    I have never heard of this on any ECU cat system that I have come across before as for the cat to function properly the engine has to run in closed loop all the time. I will monitor the o2 sensors while riding to see what happens!
    Today I got out and tried the bike for a good long ride with the pair valve blocked. The response from closed throttle at slow speeds is a lot better however the throttle is still jerky at say 3000 in second when riding along on a steady throttle (if that makes sense)
    Also I thought that on deceleration without the pair valve that the mixture would be rich in the cat and I verified that as I get a sulphur smell when going down hill with throttle closed.
    From this you can say that if the pair valve is to be disabled for any length
    of time the cat would have to be removed. If not I can't see it lasting too long. Honda it looks like add additional air from the pair system to pass emisions on deceleration. To me right now it looks like we would have to remove the cat, add the resistors, remove the pair, sync the starter valves and remap using a pc III. It looks like you are almost at that point anyway
    I am going to install a lot of test equipment and try to see whats happening?
    I don't see why it's the way it is, alright the vstrom I had was not as highly tuned, the Ducati ST3 is a v twin, but the speed triple is highly tuned and passes emisions AND the mapping is spot on!

  8. #21
    Registered User Array Chumly's Avatar
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    Nice to make your acquaintance!

    I assure you the engine management system does not run in closed loop unless it’s steady-state-cruise-steady-throttle. The rest of time the ECU runs in open loop and the O2 sensors are not used, the ECU and then relies on the various other "inputs" such as TPS and of course the OEM map. Note the PCIII does not change the OEM map as the PCIII is after the ECU.

    A lot of people on VFRD have done a cat-ectomy, also FWIW I have not heard of people with failed or overheating cats from PAIR disabling.

    I have talked extensively with Honda Canada and the top whizzes on VFRD I own the shop manual and have an OK background in this stuff but I don't make a living at it like you, alas. BTW the reason Honda did this silly stuff was to meet emissions regulations not in place yet (I cannot recall the standard but it's CARB 2010 compliant or some such).

    I truly welcome any ideas and input you have on making the throttle action more linear.
    Last edited by Chumly; 03-18-2007 at 08:41 PM.

  9. #22
    steve tech
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    Quote Originally Posted by Chumly View Post
    Nice to make your acquaintance!

    I assure you the engine management system does not run in closed loop unless itís steady-state-cruise-steady-throttle. The rest of time the ECU runs in open loop and the O2 sensors are not used, the ECU and then relies on the various other "inputs" such as TPS and of course the OEM map. Note the PCIII does not change the OEM map as the PCIII is after the ECU.

    A lot of people on VFRD have done a cat-ectomy, also FWIW I have not heard of people with failed or overheating cats from PAIR disabling.

    I have talked extensively with Honda Canada and the top whizzes on VFRD I own the shop manual and have an OK background in this stuff but I don't make a living at it like you, alas. BTW the reason Honda did this silly stuff was to meet emissions regulations not in place yet (I cannot recall the standard but it's CARB 2010 compliant or some such).

    I truly welcome any ideas and input you have on making the throttle action more linear.

    Maybe let me know where you heard about the closed/open loop steady throttle deal. I have never heard of this, especially if they are trying to meet CARB standards. If this was the case then disconnecting the PAIR system or removing the o2 sensor connections would not make the slightest difference as the only time the bike would be in closed loop would be when none of these issues we are having are taking place.

  10. #23
    Registered User Array Chumly's Avatar
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    There are six main things that can exacerbate VFR throttle problems:

    1) At very low throttle openings if the SV's are not synced.

    2) At steady state when the ECU goes into closed loop the EFI fuel ratio wants to go stoichiometric and thus you can have lean surging.

    3) While spinning up through the VTEC transition @ 6,800 RPM (this changed on the ‘05’s but I’ll not bother talking about that here) there is a stumble then a hit due to the abrupt opening of the extra valves. This is most notable at smaller throttle openings at lower engine loads when transitioning slowly up and down repeatedly through the VTEC transition.

    4) At some throttle openings and gear positions etc the EFI maps too lean for smoothest performance (this one is somewhat contentious but if you look at the maps of people’s VFR's before and after proper dyno tuning the end results are most often a higher F/A at some given settings, so I give it credence and hey Dynojet thinks most modern bike EFI's are too lean at certain operational points).

    5) There is some argument that the VFR VTEC’s engine management system does not work as well as some other bikes, and if you check the 05’s on up they have made some changes such as a different (finer) injector, altered the VTEC engagement RPM, staggered the VTEC engagement/disengagement RPM's, and altered the EFI map - maybe other stuff too but that’s all I know of related to the engine management system. Understandably this one is also somewhat contentious and I do not give it as much credence as the general map leanness viewpoint because some other brands of bikes appear to have EFI systems no more (and perhaps less sophisticated) than the 6th gen on up to the ‘04’s, but OTOH you would need to ask why Honda made these tuning changes if there were no issues related to this argument. There have not been a lot of 05’s on up sold as of yet to get a picture, but the consensus so far seems to be that the engines are more tractable and more predictable.

    6) Throttle cable slack.

    In answer to your question about my sources I have already listed them in my first post and in subsequent posts to you and others as discussed.

    Honda Canada
    VFRD (there was big crash so older data is gone)
    The Honda shop manual
    and http://www.bikersoracle.com/vfr/foru...3&page=1&pp=15

    I forgot to mention I also had a number of chats with the fine people at Dynojet. I would not say they were experts with the VFR VTEC’s idiosyncrasies but they are a wealth of general tuning information. Remember I said I cannot recall the future emissions standard the VFR was targeted for........I could find out. You sound about the same age as me; perhaps we can meet up and go for a spin and a beverage sometime.

    Cheers,
    Dan
    Last edited by Chumly; 03-19-2007 at 03:39 PM.

  11. #24
    steve tech
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    Quote Originally Posted by Chumly View Post
    There are six main things that can exacerbate VFR throttle problems:

    1) At very low throttle openings if the SV's are not synced.

    2) At steady state when the ECU goes into closed loop the EFI fuel ratio wants to go stoichiometric and thus you can have lean surging.

    3) While spinning up through the VTEC transition @ 6,800 RPM (this changed on the Ď05ís but Iíll not bother talking about that here) there is a stumble then a hit due to the abrupt opening of the extra valves. This is most notable at smaller throttle openings at lower engine loads when transitioning slowly up and down repeatedly through the VTEC transition.

    4) At some throttle openings and gear positions etc the EFI maps too lean for smoothest performance (this one is somewhat contentious but if you look at the maps of peopleís VFR's before and after proper dyno tuning the end results are most often a higher F/A at some given settings, so I give it credence and hey Dynojet thinks most modern bike EFI's are too lean at certain operational points).

    5) There is some argument that the VFR VTECís engine management system does not work as well as some other bikes, and if you check the 05ís on up they have made some changes such as a different (finer) injector, altered the VTEC engagement RPM, staggered the VTEC engagement/disengagement RPM's, and altered the EFI map - maybe other stuff too but thatís all I know of related to the engine management system. Understandably this one is also somewhat contentious and I do not give it as much credence as the general map leanness viewpoint because some other brands of bikes appear to have EFI systems no more (and perhaps less sophisticated) than the 6th gen on up to the Ď04ís, but OTOH you would need to ask why Honda made these tuning changes if there were no issues related to this argument. There have not been a lot of 05ís on up sold as of yet to get a picture, but the consensus so far seems to be that the engines are more tractable and more predictable.

    6) Throttle cable slack.

    In answer to your question about my sources I have already listed them in my first post and in subsequent posts to you and others as discussed.

    Honda Canada
    VFRD (there was big crash so older data is gone)
    The Honda shop manual
    and http://www.bikersoracle.com/vfr/foru...3&page=1&pp=15

    I forgot to mention I also had a number of chats with the fine people at Dynojet. I would not say they were experts with the VFR VTECís idiosyncrasies but they are a wealth of general tuning information. Remember I said I cannot recall the future emissions standard the VFR was targeted for........I could find out. You sound about the same age as me; perhaps we can meet up and go for a spin and a beverage sometime.

    Cheers,
    Dan
    Sounds good, I will take you up on that!
    My bike is an 05, so I don't think they have achieved much.
    I'm originally from the UK so I always pick up BIKE magazine, its ironic but this months tests the VFR against the BMW 800. They really pick fault with the "snatchy" throttle the VFR has and even write an article about what happened to your wonderful engine Honda?
    I will bring my bike into the shop at work one day and measure the emissions and do some experimenting with the o2 sensors.
    If you pm me your email I will scan the article and send it you if you wish.

  12. #25
    Registered User Array Chumly's Avatar
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    I would like to read that article sure! Iíve pmíd you

    Does your bike have the clear turn signal lenses? If so that hopefully will confirm it has the latest changes I talked about such as the different (finer) injectors, altered VTEC engagement RPM, staggered VTEC engagement/disengagement RPM's, and altered the EFI map.

    Donít get me wrong I still think itís a nice bike. I was going to sell mine but after all the farting around getting it running decently I canít really find anything I like that much more to warrant all the hassles of selling and buying.

    Iíll say this: Honda sometimes has wacky ideas about how to apply technologies, OTOH Honda sometimes gets it amazingly right too.

  13. #26
    steve tech
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    My bike has amber signal lenses, its an 05. The 06 has clear.

  14. #27
    Registered User Array Chumly's Avatar
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    Then I made a mistake in that the most recent engine management changes I talked about start with the '06 model year. Sometimes it’s hard to remember all the trivia associated with VFR’s. Back to watching South Park!

  15. #28
    Registered User Array Chumly's Avatar
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    Hi-yah Steve,

    You might be interested in what’s happening with the 2nd generation Yamaha FZ1. It too is plagued with EFI problems, but because it’s a much better supported bike in the after-market (Ivan etc) there are now solutions which we cannot get for our VFR VTEC’s. In particular a Fuel Cutoff Eliminator is unavailable for the VFR VTEC.

    My prediction is that the next 5 years are going to see more and more bikes with emissions regulations EFI issues.

    http://www.bikemagazine.co.uk/nav?pa...source=5289716


    On an efi engine, tickover fuelling is handled by injectors, but the engineers turn them off on closed-throttle coasting. Nobody should notice because the throttle is shut – so the rider won’t care – and there’s less fuel, unburned or otherwise, in the exhaust mixture.

    But if you cut off fuel to an engine spinning at, say, 5000rpm (with pistons whizzing up and down 40 times per half second), the motor purges itself of fuel (in fact an efi motor purges itself of everything – with the throttle closed there’s no air either, which creates a vacuum, a problem in itself).

    So now the inlet tracts and combustion chamber of the efi engine are ‘dry’. Which is okay if you keep the throttle closed and run the engine down to tickover – the injectors just switch back on again to keep the motor running. But what happens if the rider opens the throttle again before that point?

    Engineers call this process ‘fuel reinstatement’. The rider twists the throttle and the bike’s ECU reads this, telling the injectors to deliver fuel into the air-stream in the throttle bodies.

    At the same time, a butterfly valve in the throttle bodies opens, allowing air into the inlet tracts (the ECU also opens secondary butterfly valves – slowly – using a servo, to control the transition from closed throttle to open throttle).

    So fuel is squirted from the injectors and the butterfly valves are partly open to let air into the engine.

    But because the motor is completely fuel-less, the new fuel has to travel the length of the inlet tracts and into the combustion chamber before it can burn. It’s not a big distance, but it’s far enough to introduce a delay between opening the throttle and getting a response.

    Also, some fuel from the initial injection is drawn out of the fuel/air mixture and re-lines, or ‘wets’, the walls of the inlet tracts, adding further delay in the petrol reaching the cylinder.

    The cumulative effect is called the ‘fuel transport time’ – and the longer that is, the worse the throttle snatch.
    Last edited by Chumly; 03-24-2007 at 02:45 AM.

  16. #29
    steve tech
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    Quote Originally Posted by Chumly View Post
    Hi-yah Steve,

    You might be interested in whatís happening with the 2nd generation Yamaha FZ1. It too is plagued with EFI problems, but because itís a much better supported bike in the after-market (Ivan etc) there are now solutions which we cannot get for our VFR VTECís. In particular a Fuel Cutoff Eliminator is unavailable for the VFR VTEC.

    My prediction is that the next 5 years are going to see more and more bikes with emissions regulations EFI issues.

    http://www.bikemagazine.co.uk/nav?pa...source=5289716

    Yeh thats the same mag. I got the VFR issue out of I sent you.
    Just finished syncing my starter valves. I also adjusted the chain at the same time (never done it yet so figured it's about time)
    By the way I checked the pair valve while I was at it, its open unless powered closed on throttle shut off. I did some experiments with the pair on and off while monitoring the mercury tubes. There is quite a difference between the measurements with the pair plugged or not. If you are running the pair I would sync the starter valves with it connected. If your going to plug it then sync the starter valves with it plugged. I know thats not the "Honda" way but there is quite a difference in the back pressure between the front 2 and the rear cyls. With regard to the throttle switch I am experimenting also to find when fuel cut off takes place on the Honda. The VFR has a potentiometer for a tp sensor so it would be easy enough to build iin a circuit so it never sees idle at throttle shut off at higher rpm or road speed. Thats all the guy did to fix the Yam. Ive done it before on cars.
    By the way the tp sensor is part of the throttle assembly so you dont want to Fxxx it up!! Right now I have the pair valve working again and will try the bike when the rain stops (if ever). It dosn't take very long to do the starter valves so I will see what has transpired with this adjustment first.
    Steve
    .

  17. #30
    Registered User Array Chumly's Avatar
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    I synced the SV’s the way Honda recommends in the shop manual, I can’t remember if that meant with the PAIR disabled or enabled, as that was two years ago now.

    I would really like to know the exact RPM fuel cutoff takes place, and also if it matters what gear it’s in, and also if it matters what speed you are going.

    I know the TPS is a pot and you could add or subtract resistance by either putting a resistor in series or one in parallel (whichever is required I’m not sure). I am an Electrician so I know RLC resistance / inductance / capacitance circuits.

    What I’m wondering though, is that by changing the effective overall TPS resistance so the ECU never thinks the bike has the throttle fully closed, you are in essence throwing the TPS out of sync. That would mean the EFI pulse width would be longer at all throttle positions (expect full throttle) and would make all F/A settings a bit richer. Wouldn’t it?

    I brought this up on VFRD http://www.vfrdiscussion.com/forum/index.php? but no one seemed to know and no one I have ever talked anywhere else has tested for fuel cutoff or tried to defeat fuel cutoff. AFAICT you are the first to look into VFR fuel cutoff. I did ask Ivan's Rockland County Motorcycle and he said he did not know and has no plans for the VFR.

    Great stuff man, and it sounds like you could get cool results that would make the VFR easier to operate. The question is: does the VFR use fuel cutoff to minimize emissions?

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