'06 800 cold starting weird behaviour...

Discussion in '6th Generation 2002-2013' started by Sam99, Feb 14, 2017.

  1. Sam99

    Sam99 New Member

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  2. Expvet

    Expvet New Member

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    I had a similar issue on my 06 and while adjusting the throttle bodies found a vacuum hose with a small leak. Once I replaced it the idling returned to normal. If you can get a hold of a vacuum gauge check them (or have a mechanic check them). Going on 11 years old and high heat dries them out and small cracks are not uncommon.
     
  3. Sam99

    Sam99 New Member

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    Aha. Thank you. The hoses in the middle of the throttle body that run to the starter valves?
     
  4. Sam99

    Sam99 New Member

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    6.30pm this evening, 6 degrees C, having sat since 10.40am, I pressed the starter, straight to 2000 rpm, stayed there for 10 seconds, rose to 2500 rpm, stayed there till at running temperature. So it's intermittent now. Sigh.
     
  5. Sam99

    Sam99 New Member

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    Hi chaps, the other morning I disconnected the clutch switch and started up, revved immediately to 4500rpm without me touching the throttle. I reconnected the clutch switch, revs dropped immediately to 2500rpm. This morning, 6 degrees C the bike started, revs dropped to 900rpm, I gave it a little throttle to keep it going, (which it doesn't seem to enjoy, much) till the revs pick up to around 2500rpm... I put it in gear with the FIWU still doing its thing at 2000rpm and there was no rise in revs... aaargh!
     
  6. Sam99

    Sam99 New Member

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    I'm putting a new clutch switch on, see what happens... I've been doing 200 miles a day for the last three weeks, and it does seem to be starting better.
     
  7. Expvet

    Expvet New Member

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    Sorry for the delay, just came back from vacation. Snaking around the throttle bodies (no need to remove them) are a series of vacuum hoses, most of which are joined via plastic T couplers. It was on one of these hoses that I found a few small barely noticeable splits in the rubber. Once I replaced it with the easy to find auto part store equivelant all problems were resolved and it now revs up during cold morning starts and settles down once the proper idle temperature is achieved.
     
  8. Sam99

    Sam99 New Member

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    Update! So I had a full service done. All fluids, clutch, brakes, oil and filter, coolant, fork oil. All valves checked and all spot on at 37k miles, and not checked before. Rear linkage dismantled and greased. Replaced thermostat with OEM. Swapped throttle bodies for an unmolested (fast idle wax unit as set in the factory, unadjusted, paint mark on the thread unbroken) secondhand complete assembly that I picked up on eBay. Now it runs perfectly. Started today at 1 degree C, didn’t stall. No more weird revving in gear at temps below 60 C. I don’t know what voodoo Honda apply but the dealer I bought it from (Dobles) were unable to fine tune it, and gave me some BS about “they all do that sir”.
    £550 to do all the above by my local mechanic. Now I trust my VFR800.
     
  9. OCLandspeeder

    OCLandspeeder New Member

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    This sounds all too familiar for me. I realize this response is too late to help you but here goes anyway....

    I went through this whole saga of having a high idle and at first I worked on and replaced a few things and none worked. The issues began AFTER I did a Starter Valve Synchronization. As another knowledgeable VFR owner told me, I had a "Runaway Idle" issue. This issues is usually caused by excess air entering your cylinders from the Starter Valves and/or downstream of it. The vacuum hoses leading to the MAP sensor (located below each throttle body) reads this extra air entering your throttle bodies, so it compensates by telling the MAP sensor to increase the amount of fuel. This in turn raises your idle. This is why your spark plugs look "wet". They are getting way too much fuel at idle.

    In my case, the bike would start and rev up to 2,500 RPM, then VERY slowly come back down to a still-too-high 1,800 RPM at full operating temperature. Sometimes when the bike got really hot the idle dropped to 1,600 RPM but that was still too high. I replaced ALL the vacuum hoses to the Starter Valves with no effect. I replaced the Throttle Body air seal boots with new boots with no effect. I replaced the MAP sensor with no effect. I was quickly running out of options until I carefully looked at the Starter Valve mechanism, specifically, the plate that the Wax Idle Unit pushes up against. There is one small bolt that adjusts how far the Idle Unit can push against that SV plate. It has a factory white paint on it to indicate "DO NOT ADJUST". I realized after staring at this mechanism that the Idle Unit adjuster screw allowed the Idle Unit to push the SV plate just enough to pull the Starter Valves slightly more open enough to raise the idle. So I loosened the Idle Unit bolt just a notch to allow it to release the plate and allow the starter valves to "close" fully to their natural position (when properly synchronized). Viola! Runaway idle fixed!

    My bike's idle is now back to a normal 1,200 RPM at full operating temp. When cold, it will rev up to 1,800 RPM but slowly drops down to normal as coolant temp rises.

    My suggestion to you is to first make sure all your Throttle Body Air Seal boot bolts are tight per factory spec. All 8 of them. You will need a very long screw driver and the airbox needs to be off the bike. Once you have verified these are tight, make sure all your vacuum hoses are secure & leak free. If the high idle persists, inspect the Idle Unit mechanism actuation against the Starter Valve plates. Make sure the Idle Unit is NOT pushing against the SV plate at full operating temperature. It should only push against that plate when engine is cold. If the Idle Unit is putting even a little pressure on that plate at full operating temp, the SV's are being forced open,which causes your high idle. If this is the case, adjust the Idle Unit adjusting screw just a tad to ease the pressure off the plate. Remember to do this at full operating temp so that you can verify the idle settles at 1,200 RPM. Also do NOT loosen that screw too far because you still want the Idle Unit to push against the plate when the engine is cold.

    Good luck. Don't let the dealership touch your bike anymore.
     
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  10. MotorBikeMike

    MotorBikeMike New Member

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    Hey man. I have the exact same case as what you experienced. Very high idle, revs climb on their own to 4000RPM when releasing the clutch slightly from a stop in first gear. Or runaway idle as some call it. Very sketchy to ride like that in a corner. Using the clutch as the throttle is never a good idea...lol

    So I have also been racking my brain.....until I found your thread here. So in your case, if I have it correctly, was the wax idle adjustment? Is that all it was in your case?

    My bikes symptom's are: Super high idle 2500-3400 rpm sometimes even as high as 4000rpm. Only drops to 2000 rpm at warm idle. Runaway throttle in first gear when slightly releasing the clutch.

    Thanks in advance
     
  11. GreginDenver

    GreginDenver New Member

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    The most important part of your question is this statement: "My bikes symptom's are: Super high idle 2500-3400 rpm sometimes even as high as 4000rpm. Only drops to 2000 rpm at warm idle. Runaway throttle in first gear when slightly releasing the clutch."

    This statement indicates that your VFR's wax-core fast idle unit isn't working properly. This will be happening due to 1. age-hardening of the wax-core itself and/or 2. a blockage in the two small coolant lines that allow engine coolant to flow into and through the base of the wax-core.

    If coolant does not flow through the base of the wax-core the "wax" will not heat up and expand. When the wax-core heats up and expands this will "release" the wax-core unit's pulling force on the throttle body starter valves (this pulling force exerted by the wax-core when cold overrides the idle normally controlled by the throttle body starter valves).

    Your first move should be to replace the bike's wax-core fast idle unit. These wax-core units lose their ability to work properly over time and your VFR is more than 10 years old now. Honda views the wax-core fast idle unit as a "consumable item" that needs to be replaced every so often. Also, when you remove the wax-core unit to replace it you should also verify that the two small coolant lines leading into and out of the base of the wax-core unit are clear, properly connected and capable of flowing coolant as they are designed/intended to do.

    If you're unwilling to replace the wax-core fast idle unit there's no sense in asking any other questions about your VFR's idle problems.


    How much do you know/understand about the VFR's wax-core fast idle (automatic warm up)? Have you disassembled the bike to have a look at the VFR's throttle body assembly? If you have a good long look at the mechanism you will probably be able to understand how it works.

    Also, there is no "adjustment" available on the VFR's wax-core fast idle mechanism. There are several areas on the VFR throttle body that come from the factory marked with WHITE PAINT. Any area that has a dab of WHITE PAINT on it is considered Off-Limits, do not touch.
     
    Last edited: Mar 12, 2018
  12. Sam99

    Sam99 New Member

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    Hi Mike, thanks for your message. In my case I replaced the entire throttle body unit with a nice one I found on eBay. My mechanic also reported that the clips around the throttle body rubbers (holding it onto the four intakes were LOOSE) so he felt there could’ve been a little air leaking in, too. Either way, the clutch out/revs shoot up problem is totally GONE. I’ve read that some people give the FIWU a little tweak, only 1/4 or 1/2 turn but that’s usually because they aren’t getting a high enough idle. I think it’s a good idea to check the rubber boot clips are tightly done up, and that the quite small bore that the coolant passes into and out of the FIWU is clear. Sounds to me like your idle when warm is a little high at 2000rpm... I keep mine at around 1400. Bringing that down a little may help. Good luck, let us know what you find!
     
  13. Terry Smith

    Terry Smith Member

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    Glad to say my 99 model has NO wax unit; if I don't like the fast idle, I can adjust a lever on the bars!

    The idle speed is controlled by air flow into the engine, and that can come from the throttle butterflies, the starter valves or any other air leak, specifically the vacuum lines (unplugged or holed) or the inlet rubbers/clamps.

    When the engine is warm, the idle speed SHOULD only be controlled by the idle adjuster screw bearing on the starter valve plate. If the FIWU is exerting any control over the starter valve plate when warm then there is your root cause.

    When cold, the idle speed is set by the FIWU bearing on the starter plate.

    The movement of the FIWU needs to be in conjunction with coolant temperature. If the flowing coolant cannot reach the FIWU, then the unit cannot respond as the temperature climbs. If the coolant can flow freely through the unit, then the unit itself would be suspect.

    If the FIWU is moving freely with temperature change (and I guess you could test this with by immersing it in hot or cold water like a thermostat) and it is holding the starter valves open when hot, then I would suggest you need to break the special Honda paint and adjust the nut and allow the starter plate to rest on the idle screw instead.

    Now as to why revs would shoot up when the clutch is released is a bit of a mystery. I do know from experience that the flapper valve in the airbox is held open when the clutch is pulled in (in gear), and closes when the clutch is released. When the clutch switch gets a bit dirty you can get some intermittent flapper operation which can be heard at idle. The flapper is driven by vacuum, so my guess is that when the flapper solenoid opens, a new air leakage path is created. The most logical place for the leak would then be between the solenoid and the flapper actuator, maybe the hose is damaged or unplugged (the flapper actuator is the round brass device on the airbox lid).
     
  14. MotorBikeMike

    MotorBikeMike New Member

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    Amazing help....Thanks a bunch man. This seems the most logical part failure to me too. If I am going in there to inspect it, and since it is a consumable part, it doesn't hurt to replace it regardless if this is the source of the problem or not. Thanks again
     
  15. MotorBikeMike

    MotorBikeMike New Member

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    I cant believe how supportive you all are. Thanks again for adding input to my issue. Much appreciated and am very grateful. I will replace the FIWU and let you all know if this resolved my issue. Its probably going to be in a week or so. No rush to get this fixed as its still cold out.
     
  16. GreginDenver

    GreginDenver New Member

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    While you're making the effort to dig deep into the cramped and crowded "V" of your bike's engine you should also remove and replace the thermostat. The thermostats on VFRs don't age well and can fail (get stuck or developing a sticking point in its range of motion) in just about any position (full open, full closed or anywhere in between).

    Here's something else you should know about replacing the FIWU wax-core unit. In October of last year I replaced the FIWU wax-core unit on my '01 5th Gen as part of a general refurbishment effort on the bike (the '00 and '01 5th Gen also has a FIWU wax-core unit, it's arranged on the throttle body assembly slightly differently, but overall it operates exactly the same as the 6th Gen unit).

    The first time I started the bike up after doing all of my refurbishment work, which included draining and replacing the coolant and replacing the 16 year old thermostat, it was obvious that after the coolant refill there was air in the coolant lines to and from the FIWU wax-core unit. On its first start up my '01 5th Gen acted very similar to your described problem in this thread, idling very high for the first few minutes of operation. Then as the coolant in the engine heated up something happened (I guess the cooling system "burped" out the air in the FIWU lines) and the FIWU unit suddenly started working, controlling (reducing) the idle speed to normal levels. After the first post-replacement start up my '01 5th Gen has idled perfectly on every cold start up.
     
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  17. MotorBikeMike

    MotorBikeMike New Member

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    Hmmm good to know. I looked up the burping procedure on this bike, and its pretty basic. Not a fan on how they want you to burp the air out. I will make sure all the air is out by attaching a large funnel to the rad cap and let it idle. Similar to the automotive way with rad caps. I think that would be better. The wax unit appears that it can be replaced while keeping the throttle bodies in place. But to do the thermostat, they will need to be removed. I don't know if I really want to remove the TB's from the bike. Looks like a can of worms to me
     
  18. GreginDenver

    GreginDenver New Member

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    It is a can of worms, it had to be. Honda built an amazing motorcycle when it created the VFR, unfortunately a good bit of complexity was one (slightly negative) side-effect.

    But, you can do it if you use a methodical approach. I took a lot of pictures before and during disassembly to document where things were plugged in and the proper routing of all the electrical lines and vacuum lines so I could guarantee proper reassembly. I read forum posts and watched various "how-to" videos on Youtube to determine the best way to remove the throttle body assembly. I settled on the method that directs you to use heat, like from a hand-held hair drier, to soften up the connector rubbers and then do the prying upward of the throttle body assembly out from the connectors by using a cargo strap looped under one corner of the aluminum alloy casting of the throttle body assembly and up over your own shoulders so you can use your arm strength pressing down on the bike's frame for leverage to pop it out of the connectors. This worked well for me.

    It felt good (an accomplishment) to successfully disassemble and reassemble the VFR.
     
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  19. OOTV

    OOTV Member

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    I'm with you there! I think the Honda mechanics must have very small hands! Getting to some of the hoses and screws is near impossible at times. I will say though, if you're going to pop off the TBs, might as well change out the tstat, especially of you haven't changed it before. When I had to replace my water pump on the 6Gen, I figured since I was draining the coolant and both the tstat and water pump were the same age, I did a preemptive strike and replaced the tstat while I was at it. Similarly with the 5 Gen, I pulled the injectors to get them professionally cleaned and since I was changing out the water pump, I went with new hoses while I was at it, plus the tstat. An ounce of prevention is worth a pound of cure, or something like that.
     
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