Engine sputtering and backfiring

[grampi]

Three weeks ago I bought a 2013 Roadster that I'm having an issue with. The bike has ram air, and TORS exhaust with a crossover pipe (the one from Australia). The bike also has been professionally dyno tuned. Shortly after buying the bike I noticed it was doing two things. Originally I thought they were separate issues, but now I believe they may be related. When accelerating slowly, the engine sputters and misses (and sometimes even backfires) with the throttle position just above idle. It's most noticeable when shifting, but yesterday I was able to hold the throttle position right at the spot it occurs for a good 2-3 seconds and the engine was missing like crazy, and it backfired. The other thing it's doing is sputtering, pretty much in any gear from 2nd on up, when holding the throttle in a steady position with the RPMs between about 2500 and 3000. The engine seems to run fine at idle, and at any other throttle position other than just above idle. WOT it runs fine. The person that tuned it made a new map as he saw an area of the old one that was a little lean, but the new map didn't fix the problem. Any idea what could be causing this? Thanks.

 

[Mittzy]

Maybe make a copy of your tune (using TuneECU) and ask @HansO if he would look at it

 

[grampi]

Maybe make a copy of your tune (using TuneECU) and ask @HansO if he would look at it

I really don't think it's an issue with the tune, since the new one made no difference...

 

[idk]

Check simple things like the vacuum hoses and ignition coil leads. Also check the TPS settings.

 

[R3Tex]

+1 on what Ian said ^^^

 

[grampi]

I can check the coil leads, but I have no idea where all the vacuum lines are located, and I have absolutely no idea how to check the TPS...

 

[R3Tex]

Lift the tank and you will find several vacuum lines near the fuel rail. You need to check both ends of each tube that comes off the throttle bodies, etc. Are you getting a check engine light? Usually when there is a vacuum line loose the bike will throw a code that you can read in TuneECU. There is a sensor under the tank that has three lines going to it that has come loose on me twice...each time causing similar issues to what you are describing. When checking coil leads remember the one up front. It's a little difficult to get to, but worth checking.

 

[grampi]

Lift the tank and you will find several vacuum lines near the fuel rail. You need to check both ends of each tube that comes off the throttle bodies, etc. Are you getting a check engine light? Usually when there is a vacuum line loose the bike will throw a code that you can read in TuneECU. There is a sensor under the tank that has three lines going to it that has come loose on me twice...each time causing similar issues to what you are describing. When checking coil leads remember the one up front. It's a little difficult to get to, but worth checking.

No check engine light...and I can't read anything using tune ECU as I don't have the program or a laptop...I will check the vacuum lines and coil leads after work today...

 

[Busaboy]

No check engine light...and I can't read anything using tune ECU as I don't have the program or a laptop...I will check the vacuum lines and coil leads after work today...

$20 for a TuneECU compatible adapter. Will work with any PC with a USB port, even a desktop. The program runs out of the folder it is put in. It does not need to be installed so it will not make changes to the PC. It does not get any cheaper or easier than this......

 

[idk]

You can also get it for Droid.