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Hi all. This is the first time I am using this forum.  After very little use I decided to clean around the Carbs and do a general tidy up to my 2003 vfr 800. Now it responds very poorly (chucking) in low reves.  However when I disconnect the map sensor the bike appears to run fine.

Any advise is appreciated.

 

Thanks

Mark 

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Hi Mark.

Welcome to the forum, we will need to see a good picture of your bike.

 

Carbs!! Did you clean the Throttle Bodies? If so were you aware of the Warning not to use commercial cleaners?

Are you disconnecting the MAP sensor electrically or removing the vacumm input? Did you remove the intake funnels and place them back into the same position? Did you disturb any of the linkages, or alter any of the Starter Valves? Did you remove any of the Vaccum hoses are there any damaged vac hoses or any vac hoses not connected? Did you have an Fi MAP fail code indication, prior to disconnecting it?

 

 

 

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Hi Grum, and thank you for your email.  You have given me lots to consider. 

 

Carbs!!  I did use this but only after the I noticed the problem!

Are you disconnecting the MAP sensor electrically or removing the vacumm input? Just disconnecting the electrical part!

Did you remove the intake funnels and place them back into the same position? It is possible the intake funnels are in the wrong place - I will have to double check this!

Did you disturb any of the linkages, or alter any of the Starter Valves? I may have disturbed one of the starter valve - does this need re-synchronizing ?

Did you remove any of the Vaccum hoses are there any damaged vac hoses or any vac hoses not connected? I believe these to be fine.

Did you have an Fi MAP fail code indication, prior to disconnecting it? No - the bike appeared to be only running on 3 carbs, periodically but as soon as I disconnected the map sensor it runs fine!

 

Lower picture shows damaged Molybdenum coating allowing air to bypass causing fast idle. The picture attached is what I am also seeing!

 

I will start with the intake funnels but what would you advise otherwise and many thanks again for your help.

 

Mark

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M8. There's no doubt that somehow you've induced the problem. Go back and thoroughly check Everything you did.

There are no "Carbs" on a 2003 VFR!

- Intake funnels - You will have two short and two long. The short ones belong in intake 2 and 3, longs to 1 and 4. Cylinder layout is FRONT 2=left 4=right, REAR 1=left 3=right. (Shouldn't greatly effect things if you have them wrong)

- If you've disturbed the Starter Valves then yes they will need re-synching. This will help Idle and smoother slightly open throttle control.

- In cleaning the intakes do you feel you've damaged the Molybdenum coating? That could upset the idle air balance between cylinders, you could be looking at a new set of throttle bodies!

- Is there any chance you've  gotten the cleaner into the vac hoses and into the MAP sensor, damaging it?

- Suggest you clear ECM fault codes reconnect the MAP sensor then re run your bike, see if the ECM flags up a MAP Sensor fail code.

- Just confirming, the vac hose on the MAP Sensor is going to the 5 way joiner right

 

Good Luck.

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Hi again and thanks for the advice. It is definitely my fault and I have learned from it.  

 

Thanks again

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Hi again, I just want to give you an update. The problem was very simple in the end. I had the map sensor incorrectly connected. 

 

Thanks again for your help

 

Mark

 

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12 hours ago, MG800 said:

Hi again, I just want to give you an update. The problem was very simple in the end. I had the map sensor incorrectly connected. 

 

Thanks again for your help

 

Mark

 

Thanks for the update. Glad it was a simple fix.  Enjoy your ride.:wheel:

Cheers

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