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I have a 2009 KFX 450r with cp 98mm piston, +3 hot rod, fuel custom intake, open air box, NGK jeep coil, full fmf power bomb Ti 4.1 exhaust, PCv and auto tune. Low to mid throttle it starts to shit and pop then clears up. Once in a while I'll go thru the gears and runs clear. Thanks in advance!
 

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I have a 2009 KFX 450r with cp 98mm piston, +3 hot rod, fuel custom intake, open air box, NGK jeep coil, full fmf power bomb Ti 4.1 exhaust, PCv and auto tune. Low to mid throttle it starts to shit and pop then clears up. Once in a while I'll go thru the gears and runs clear. Thanks in advance!
What does your spark plug look like...sooty black, coffee brown or white...???

Also what octane fuel are you running...105~112 octane is recommended 13.5:1+ piston compression
 

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I have just built a kfx with +3 hot rod, stage 2 cam, dasa exhaust, PVC autotune, fci intake, jeep coil, and dasa has the head porting it right now. I havent quite got it back together yet. I'm wondering have you had the chance to ride yours for a while with the current mods, and it was running correctly?

And cutting out is usually lack of fuel. What kind are you running?

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Im running 110 VP ....I checked the screen and fuel pump. Appear to be ok and working. Don't have a fuel pressure gauge so not sure if it's up to pressure. I did order a rebuild kit anyway. The roll over sensor has been glued already. Made sure the map sensor vacuum is intact. Im really hoping the pump rebuild does it
 

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I would take a peek at the harness ground wire on the frame right behind the gas tank just to make sure.
Widebands die over time. It will stop reading clearly at low rpm before it doesnt read well at high rpm.
Do you know your map is correct?

Spark plug color is right. But if it just started this than it would look right.

Make sure the wire from the coil to the plug is not coming lose/out of the coil.

At high rpm the spark plug is almost lit constantly so if there were a misfire, here and there, then you would notice in low rpm far more than at high rpm.



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If your fuel is leaded it destroys wideband sensors and that's what your pcv autotune uses. If its leaded I'd switch the wideband out first. I'll be using sunoco unleaded 260GT fuel.

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I’ve had a failing ignition coil and low fuel pressure cause the exact same issue

If your not running an upgraded coil it’s a good time to pick one up
 

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I agree...! check your O2 sensor...!

Check your fuel pressure 43 psi...Also check your injector is misting the fuel properly or starting dribble...

Also check your map in your software to be correct..also check for the latest firmware update from dynojet...

If everything checkout to be good...

Check your compression ratio
 
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