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Discussion Starter · #1 ·
hello everyone, I am new here and I know this has been covered a bunch of times however the issues I am having dont seem to match anything ive read so far.....
To start off the bike is a 2007 R6(s) it currently has a little over 6,000 miles, coffmans shorty exhaust, BMC air intake, and, Bauce Racing ECU flash.
the problem im having is the bike is stuttering/hiccuping/misfiring call it what you will at around 9,800-10,000 rpm WOT when I roll of the throttle and ease back onto it the bike passes 10,000rpms and then instantly pulls hard again now this only happens in 4th, 5th, and, 6th gear not 1st and 2nd and 3rc those gears pulls strong all the way to redline.
recently ive changed the spark plugs and coils ive tested the coils with an ohm reader and they are within spec and so are the spark plugs. I should mention I put the dual electrode plugs in and the coils are the mitsubishi ones.
can anyone please help me with this I am stumped I guess the next things I need to check are fuel pump and injectors but why isnt this happening in 1st 2nd and 3rd gear?? Ive been at this for months and cant figure it out.
 

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Dunno. Think it could be leaning-out ? Could be ECU programming. If that's the cause Bauce will have seen and recognize the issue. If you unplug and cap the vac line to the fuel pressure regulator, that will close off the return line. Fuel pressure can then be measured to check against spec.

On a hot engine, enter diag mode and verify that TPS is incrementing/decrementing smoothly with no jitter. Can't really simulate the vibrations experienced during engine operation but might be able to tap on it a little.
 

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Discussion Starter · #4 ·
Thank you for the reply!! I forgot to mention I did check tps in diag mode if I remember correctly tps was at 15 or 17 to 97 went smoothly up and back down no jitters there. I also had a few codes stored in diag but no active codes I also went ahead and cleared codes but no difference. I did contact Bauce and they said the only thing they can do is put the ecu back to stock to see if that does anything different so I felt that wasn't really worth it. It's just odd that the issue happens at around 9,800 and then is fine again once it passes.
 

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AFR gauge would let you know whether it's leaning out.
 

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Discussion Starter · #6 ·
AFR gauge would let you know whether it's leaning out.
You are right I could go that route the one shop I had the bike at locally swears that I need a power commander and that will make all my problems go away they think the problem is within the ecu but I find that hard to believe. Can say the old plugs I took out which to my knowledge are the stock ones looked perfect a light tan brown color not white or black.
 

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Watching my gauge on my completely stock setup, the ECU does appear to very liberal at 75% or greater of throttle. But I have the stock "slip on" which combines the resonator, catalytic converter and muffler in one unit. If you've replaced that, all you might have is just a muffler. I don't believe it'll hurt to pull vacuum from the FP regulator and do a test run; or play around with fueling a bit. It may help eliminate some possibilities.

Font Parallel Screenshot Number Document
 

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Discussion Starter · #8 ·
I have noticed recently that when I turn the key and fuel pump primes every no and then it will make 2 different noises so at first when I turn the key it will be a slightly higher pitched noise and then quickly change to its normal hum is that normal or is this an indication my fuel pump is on its way out?
 
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