I moved a 2008 KP from Virginia to Canada. My Bike has a VFC –III and Vic Swept pipes. I’m getting a lot of backfiring when letting off on the throttle and/or down shifting. Real backfires – not pops. This seems to happen more when the engine is warm and not when it is cold. I’ve also had it die on me twice while slowing down to stop or while rolling to avoid a pothole. Could my VFC require readjustment because of the change in air temp – Now running too lean? Should I disconnect the battery to reset any adaptive settings in computer?
I checked my spark plugs and they look fine. I also unhooked my O2 sensors with no change. Should I try bumping up the VFC settings?
Guess I’ll have to install an IAV at some point? Exhaust gaskets?
It sounds like it may be running pretty lean. It runs good cold because the startup gets an extra rich mixture for a short period.
You may need a different map or TPS adjustment. Or it could be a vacuum leak ,like maybe a cracked intake boot
Could be lots of things and I'm sure youre about to hear every suggestion in the book and some that arent.
You say you havent got an IAV?
Id be fitting one and trying to adjust it to its best.
Ive had no experience with the VFC3 , I went the PCV dyno route
VFC3 required manual tuning I take it?
You could try richening it up down low.
Doubt moving to Canada would make your exhaust gaskets suddenly start leaking.
If all else fails you could try riding south
I would contact Loyd, Rylan, KevinX, or Kyle and ask for VFC settings to start with. You basically have no idea where it's set and if it has run good since the mods were installed if I understand correctly. Your issue may be as simple as a good base for the VFC3.
with bike warmed up pull both cheese wedges and spraying some carb cleaner up at the throttle bodys WD-40 will work to.
If idle picks up or bike dies you have a air leak. Air leak will cause back firing.
DO THE FIRST THING CHECK BATTERY BOLTS FOR BEING TIGHT
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OK, Tried adjusting the "green light only" function of my VFC-III. Originally in Virginia this was set to 4. I made adjustment to the VFC, see pics below. It helped with the “popping” but how do the plugs look?
Here's a picture of new spark plugs after 50 miles of city driving at with green function set to 4.5.
Here’s after 50 miles with green only function set to 5.