High Idle/Unintentional Throttle whoas

Discussion in 'Mechanics Garage' started by MotorBikeMike, Mar 12, 2018.

  1. MotorBikeMike

    MotorBikeMike New Member

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    Hey there fellow riders,

    I have a 2009 VFR800VTEC wABS. Mods are full exhaust with cat delete, flapper, snorkel and pair, PC5 .

    What I am getting is a very high cold idle which varies from 2500-4000rpm when cold which will settle down around 2000-2200RPM when warm.

    Another symptom is that when I am in first gear, stopped, and want to start moving, (without any throttle application) the revs climb all on their own to around 4000RPM when i start releasing the clutch lever. Does it cold and warm.

    I tried searching and have come up with a possible Fast Idle Wax Unit that could be the culprit. Either its defective or requires adjusting.

    Can anyone shed some light on this issue? Is it a common thing with this bike?
     
  2. Allyance

    Allyance Insider

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    I will leave the cold idle issue to others, but the slight increase in RPM is normal (built into ECU) when you start out. Probably more noticeable with higher idle.
     
  3. MotorBikeMike

    MotorBikeMike New Member

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    Its definitely not normal. The bike did not do this last year. Its actually applying a decent amount of throttle all on its own to get the bike to rev up to 4000RPM. The Idle when warm is around 2000RPM. I would blame this symptom on the high idle, if the revs wanted to stay at 2000RPM. But that's not the case. Its such a odd sensation.

    Thanks for your input and help though. Much appreciated
     
  4. OOTV

    OOTV Member

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    Regardless of whether it's warm or cold, your idle is still too high. When warmed up the idle should be about 1200 RPM +/-100. I would suggest letting the bike warm up and set the idle closer to 12k and then let the bike cool down and see what the bike idles at cold. If you did do any of these mods yourself, double check that you didn't leave any vacuum hoses disconnected or have an air leak somewhere.
     
  5. Lint

    Lint Member

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    Fuel Pressure Regulator. Third or fourth VTEC I've heard of with these symptoms. Including one I was going to buy. So of them were fixed with a new pressure regulator.
     
  6. Allyance

    Allyance Insider

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    I know the rpms on my 14 increase slightly went I pull in my clutch to start, I read somewhere this was a feature to improve starting out. If your problem is more pronounced, then you have other issues, hope you get fixed and get back on the road soon.
     
  7. Terry Smith

    Terry Smith Member

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    That high idle when you release the clutch has to be an unintended air leak through the flapper solenoid. Make sure the hose is blocked properly.
     
  8. Lint

    Lint Member

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    I left it uncapped on accident on the 05 I used to own I don't remember it affecting anything.
     
  9. MotorBikeMike

    MotorBikeMike New Member

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    You guys are awesome. The help you guys offer is astonishing. Thanks to all that replied. I think it has something to do with a faulty wax unit. I will be looking at that first as well as vacuum test all the hoses and fittings. Also will check the boots to make sure the clamps are tight for the throttle bodies.

    Anyone know of a decent parts place in Canada to order from? If I am in there inspecting the wax unit, I mind as well replace it. It is after all a consumable part (wears and tears over time)
     
  10. Terry Smith

    Terry Smith Member

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    I gave up supporting my local Honda parts supplier; the guys who work there are great, but the support from the importer (Blue Wing Honda) is hopeless as they carry very few parts and rely heavily on indent ordering from Japan. For me, ordering direct from Partzilla in the US works out faster and significantly cheaper.
     
  11. 34468 Randy

    34468 Randy Member

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    Hold off on that wax sending unit. They are expensive and you need to be quite competent mechanically speaking to replace that unit. When you get that high RPM up towards the 4K mark, is that a very sudden increase? Does it only do this when you are at a stop and about to let out the clutch lever? Does it so this just once or twice then the bike resume normal operation?

    If all this is true, it would appear that you are having the same issue I had recently. I did replace the wax sending unit (well I had the shop do it) but it made absolutely no difference.

    Have a read of this thread. It may be of assistance to you http://vfrworld.com/threads/sudden-high-revs-when-cold-starting-in-traffic.54261/#post-573694

    My problem has all but disappeared now. But I am not sure it is totally gone. I have a new tech now. He used to work at the dealership I dealt with but moved on because he did not like the way the dealership was financially screwing its customers. He is suggesting that I look for a used throttle body. I found one recently but was not in the position to buy it at that time. I am now so I will get it, then post up in the above thread the results when I get it changed over.
     
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  12. MotorBikeMike

    MotorBikeMike New Member

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    Really? Huh! So in the end, it was a couple of incorrectly routed lines and most of the problem laid within the starter valves not being synced?
    What is the Wax unit worth?
     
  13. 34468 Randy

    34468 Randy Member

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    I would have to dig into my records and find it. I will try to do that tonight and post up. Here is Canada, we pay far more than you would down there even taking into consideration the exchange rate.
     
  14. Terry Smith

    Terry Smith Member

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  15. MotorBikeMike

    MotorBikeMike New Member

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  16. MotorBikeMike

    MotorBikeMike New Member

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    So I fixed the issue. Its odd that a faulty Wax Unit could be the cause of all these symptoms. Its a bit of a stupid design. This could hurt or even kill someone with the unintended throttle application.

    But that was what was wrong the whole time. Just a faulty Wax Unit.
     
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