New Engine- Misfires around 3k

[gobsoftorque89]

Hi All,
I put an 07 engine in my 05. 07 has 2,200mi on it.
It starts up nice, sounds like its running on two cylinders, but when I went for a test drive it only runs on one cylinder at about 3k if i try to keep a steady throttle. If I lay on the throttle, it starts running better at around 4k rpm. Any ideas? I don't understand why it only does it in the rpm range. I ordered an ecmspy cable so I'm gonna try a TPS reset and see if that helps. Any other ideas?

 

[gobsoftorque89]

xb12r if it makes a difference
old motor ran fine , just second gear would slip and then catch with 22,000 mi on it

 

[gobsoftorque89]

so i've been reading up on it and it might be going into spark skip mode for some reason. I cant wait until my ecmspy cable comes.

I have window 7 loaded on my mac i hope i can use the program with that.

 

[gobsoftorque89]

Nobody? Really....

 

[Oldgit]

Spark skip is usually an "oh ****, I better cool down" mode. Check the temps. Check the fan works. Get a cable on that bad boy!

I wouldn't ride it until you've sorted the issue.

 

[Liem]

I'm having similar problems after I completely torn down my XB9s to replace a main shaft bearing. After reinstalling everything, the bike was only running on one cylinder. I knew this because the exhaust pipe leading to the rear cylinder was only warm to the touch when the bike had been running for a while. Also, the O2 sensor registered 0.5v whether the throttle was open or closed while the bike was running. Upon further inspections, the rear fuel injector was stuck closed. Resistence test was within spec but when I applied 12v directly, the injector wouldn't click. After bathing the injector in my ultrasonic cleaner, it starting clicking but after a short while, it locked up again. A new fuel injector should be here today and if all goes well, the Buell should be back on the road.

Your best bet is to first find out which cylinder is not operating. From there, check to see if it is getting air, spark, fuel and whether it has good compression. If all checks out, your problem lies somewhere else.

Good luck..

 

[gobsoftorque89]

Thanks for the input everyone. Now I just have to check my mail everyday and wait till the cable comes in.

I still don't understand why its only in the 3k rpm range. It idles fine, then runs like **** at 3k then clears up at 4k.

I'll let everyone know what happens with the bike when I get the cable.

 

[Liem]

If the tps reset doesn't do the trick and there are no codes, I would start looking for sluggish input sensors such as the O2, TPS, IAT..ect.

If the problem happens at exactly the same rpm range every time, I would look into a tuning issue. If the problem can be replicated at different rpms while hold the throttle steady, I would look into the ignition system.

If it matters any, I just installed my new used injectors and now the bike runs fabulous!

 

[christianmb]

Sounds like maybe a timing issue, or tuning issue. I would datalog it and look at the logs to see if there are any inconsistencies. That's how I figured out I had an IAT that would only malfunction sometimes for a split second.

 

[gobsoftorque89]

so got the cable. Prior to using ecmspy it idled fine and ran ****** under light throttle arournd 2500-3500 rpm like it was on one cylinder.
tried doing the tps reset, started it up. ran like ****. wouldnt even stay running without me hitting the throttle to keep it going. So, blipping the throttle i went around the block, and once it was hot then it would idle but it would bounce from 800-1300 sounding like it was going to die out. Hopped on the highway, tried cruising at 2500-3000 rpm it felt like it was getting better, not bucking as bad, but it was still not firing on both cylinders. Finally threw a code so i could get some lead on what was going on.

It threw 02 sensor always lean
short in tps sensor
short in fuel pump or always open

bike ran fine before the new engine. battery was disconnected for all repairs.pulled the airbox off and double checked all connections. going to try again tomorrow and go throw everything.

i'll redo the tps too i followed dave's instructions

 

[gobsoftorque89]

Ok so i finnally got the time to figure everything out. I took the airbox base out, and re-did the wiring. I had on of the cables routed the wrong way. Because of this it was pulling on the front injector wires. I took all connections apart and replugged them in just to make sure all connections were perfect. Switched the front and rear spark plug wires because the rear looked worn and i figured it coudn't hurt. So i put everything back on, did the tps reset one more time, this time i backed the idle out while the baseplate was off to make sure everything was perfect. I think i didn't snap the throttle enough times the last time i did it so it wasnt all the way closed. when i had the baseplate off it was easier to see when i was truely all backed out on the idle screw. reset, set to 5.5 degrees. and it fired right up perfectly. idled like a dream.

took it for a ride, and it ran like a top. I think at 3000rpm the throttle cables were pulling on the harness because i had the wires routed incorrectly was the problem in the first place, then when i reset the tps wrong it screwed it all up and cause bouncing idle.

i still have a sticky shifter but thats for another thread.

 

[gobsoftorque89]

Thanks for all your input guys. Its great that this place is just a bank of knowledge.

 

[gobsoftorque89]

What I learned from all this:
When you get frustrated when things don't go perfect the first time, retrace all your steps.

Take a break when you get annoyed, come back and look at things in a fresh light. Analyze the reference pictures you took and make sure everything is perfect. Check all plugs and wires. In my case I rushed re-wiring because I was excited to hear it run and routed the harness wrong- putting stress on the injector plugs.

And at the end do a TPS reset, pull off the airbox to make sure you are truely backed out on idle screw and make sure to flick the throttle multiple times. With the airbox baseplate off I could see why this was so important, even tho the computer stopped voltage changes, it still wasn't closing all the way without being flicked back with force. You will feel the throttle get a little stuck when it is fully closed, very slight feeling but it is definitely there.