3000 rpm hesitation and stumble

[bikenut]

Hi everyone,

I am new to the world of Buell having just purchased a 2006 XB12Ss with 7,000 kilometers on it. The bike has a drummer pipe installed and no other engine mods that I know of.

It is a bit hard to start on cold days and almost seems to be overchoked, but what is really annoying is that just around 2900 rpm lasting to about 3400 rpm, the bike goes completely flat, almost like it lost it's spark.

Other than that it seems to run fine. Any suggestions as to what may be causing this flat spot in this rev range?

I have just downloaded a copy of ecmspy and have just finished reading through the users guide but have to figure out how to hook my bike up to my lap top before I am able to glean any data from the ecm and frankly wouldn't really know what to look for in the fuel maps other than wide variances from one range to the other as noted in the users guide.

Thanks for any help given.

 

[anrkizm95]

might just need a tps reset and change plugs to ngks heres a link to reset tps tps reset and other diy

 

[dave_xb12r]

That's a common thing for buells. It can be tuned out. I've lived with my cough for over a year.

 

[Stevenc150]

A flat spot that lasts from 2900-3400 RPM ?!? Like anrkizm said, do a TPS reset and swap out to NGK Iridiums (DCPR9EIX) since you want to be sure you're tuning with clean plugs. Sounds like you're getting familiarized with ECMSpy - to really diagnose your problem, if the TPS reset doesn't help, you may need to do some datalogging to see exactly what's going on in that flat spot range. Click on my name to go to my Profile - scroll down to the ECMSpy/Tuning section and check out the Datalogging/tuning threads.

Good luck with everything - post up with any questions and welcome to the Family. [up]

 

[bikenut]

Thanks StevenC and to everyone else for the responses. Will get back to everyone with what I find.

I was googling for similar symptoms and found a similar problem on the badweather bikers forum. His turned out to be poor electrical connections so will have a check on that as well.
http://www.badweatherbikers.com/buell/messages/3842/461161.html?1279045400

 

[Mike Van V]

Jeeeeze...the TPS is a cure for the common freaken cold....
It's JUST a starting point for a good tuneup..period.

Just like most exhaust modified XB's...it needs more fuel and normally some ignition timing in those RPM locations.

You need to get ahold of the latest greatest ECMSpy type program and start playing with adding more fuel.

Funny how someone with an exhaust modified XB can say how well it runs. When actually, it runs pretty bad at many rpm's. Sure...you can wack the throttle and go past the bad spot...!
BUT...if you open the throttle slowly, or very slowly...the engine runs like crap.
Been there..! More than a few times, on more than a coupla XB's.

Mike

 

[bikenut]

What you describe is just exactly what happens Mike. Running hard you don't notice it, but at normal riding or cruising it is a definate problem.

 

[dallasb]

You just need to do a datalog. That is exactly how my bike ran when I had the stock race ecm. Now i have a modified fuel map that added a lot of fuel in the trouble areas that you are describing. I still have a slight stutter at 3.5k but all in all the bikes runs so much better than before. The reason that so many people say start with a proper tps reset is because it can and will make the bike run poorly and its a simple 5 minute ordeal. One of the main problems with our FI system (unless you have a '10 model) is that you can only tune with the rear cylinder. This means that there is no way that you can do anything but guess what the front AFV's look like. I've tried adding about 10% more fuel to the problem areas of 2.5k-4k both front and rear. Its not 100% perfect yet but its a step forward. Do not try to do ignition timing unless you are VERY familiar with tuning engines. If done incorrectly it can grenade your motor. Btw I have an '06 xb9...so for your bike I would suggest to start out adding around 15% more fuel in the problem area. Go for a test ride and see if it feels better. Adjust one thing at a time...keeping the variables to a minimum. If you use tunerpro it will get you closer to perfect than ecmspy (the older version, I'm not familiar with the mono versions) since it pulls data from more sensors.

 

[lighting]

If you don't feel confident do yourself a favor and burn a cd with your current set up just in case that you loose your data, so you can always go back to your starting point. Believe me, it happens and I'm a living proof, if you still can't set it up properly you can always buy a race ecm from new Erik Buell website or you can datalog and go to xoptic.com and talk to Mike, he can configure a set up for specific bike as long you can email the results of your run...........good luck, hope this help.

 

[dallasb]

Always make a copy of the original maps and configuration. I helped a guy not to long ago bring his ecm back from extinction by pushing a known good map back into it. I don't think that xopti does much tuning anymore but it doesn't hurt to send him a message. I know that theoctopus has a tuning seminar that he is trying to get up and running...he knows his stuff and can help you with getting hesitation out.

 

[bikenut]

Thanks everybody, once I get my cable and drivers I will be able to have a look inside the ecm. Will keep you posted.