TuneaBuell???????????
Hello! XB12S here with a K&N and Torquehammer (originally D&D) exhaust, but no other mods. I have the dreaded XB stumble up to about 4000 RPM, most noticeable in the 2000-3500 range and at part throttle. Cruising in the city and parking lot riding are no fun at all. Full throttle operation is great, and I hear occasional misfires at idle but without any other DDFI Buells around, I don't know if that part is abnormal or if it's supposed to have a skippy idle like a Harley. I have pored over many forum threads with solutions that have worked for others that have barely changed how mine behaves.
Any other diagnostic ideas or items I am forgetting? My next move is to get Megalogviewer HD and do some ECMDroid datalogging when the weather breaks. Thanks in advance for any help!
See below for what has been tried without a noticeable change in behavior.
-new intake seals
-many TPS resets
-Buell "race" tune
-new plugs
-new wires
-breather bypass
-subframe grounding points cleaned
-new ground braid
-redundant ground from subframe to coil bracket
-D&D-specific tune from Buelltooth
-Switch from D&D to Torquehammer exhaust (heard D&D is hard to tune for)
-Back to Buell "race" tune
-static timing adjustment
All sensors appear to behave normally in ECMDroid (i.e. IAT,CLT,TPS), and AFV is always within 10% of 100. There is no obvious wiring damage. I've eliminated the fuel pump as a suspect since it performs well at full throttle, but I could be wrong in that assessment. I may have forgotten a couple of items that I checked.
yugo keep us posted in what you find. I have been trying to sort the same problem on my 04 model Buell. Was able to improve idle stumble when cracking throttle open but low load/rpm cruising is still a bit jacked.
Search for my story How I Tuned My XB12 The Old Fashioned Way then look at the timing map. Mine was 0 degrees at idle and low rpm and throttle range which is too retarded. The bike smoothed out and started behaving when I advanced it in those areas a couple of degrees at a time.
Here are my maps. I cannot remember which points i changed but I think they were all in the 800, 1000 and 1350 rpm's maybe 10 to 45 throttle pos. so you can see I didn't advance them much but it sure made it smoother. I'd be curious to see your timing maps before you change them.
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Thanks everyone, I appreciate the input! I did deep-down suspect something might be ignition-related since the different tunes changed nothing about that particular behavior. I was looking at the Tuneabuell modules too but figured I'd better start small with some narrow-band datalogging and trying to get a handle on the different software packages before I spend the $. I have ECMdroid and just downloaded the trial copy of MegalogViewer HD. I think now first and foremost I'll see where my timing maps sit.
Here are my tables. Looks like I'm little bit more aggressive with idle advance. I'm actually thinking raising it up few degrees because it runs so much better.
Cossack84, I forgot to mention that mine is an '04 as well! Did you do a static timing adjustment before settling on those timing table values? Did you install a second bung or get a different header to monitor both cylinders?
I can't wait to get this thing sorted out. It's a blast to get on the throttle but that cruising/low-speed stumble really sucks the fun out of riding it, especially going around corners.