Ok, a little history.. 2010 sportster 48, running hi-flow a/c and bassani pro street exhaust. Been tuning with a Dynojet PowerVsion, the bike ran fine on the supplied map, but I've been tweaking it trying to get it optimal.

I've had a routine of data logging the bike, checking the plugs, altering the tune, then repeat. Well after my last tune, things went wrong... I had a lot backfiring, sputtering, hiccups, and seemed very hesitant at low rpm when the bike was fisrt started and the whole time I was riding it but cleared up if i twisted the throttle, until it was at operating temps, then it seemed to run fine.

I blamed this on a rich condition associated with the warmup enrichment values. So after altering the last tune, I tried it again today on my way to work. I loaded the newest tune, fired up the bike, it was doing the same thing, hiccuping, backfiring and sputtering, barely limped it out of town... I didn't understand how it hadn't improved at all after my recent changes. So I stopped, killed the bike, loaded an old original FuelMoto tune and it was still doing it! Which the bike ran fine on initially.

It almost feels if the bike idles, but one cylinder is missing, fills up with fuel, ignites, bang bang bang... From what I could see it looked like the flames were only shooting out of the rear exhaust pipe, just an assumption though.

No check engine light.

So now I'm stumped... Ended up taking the truck to work. What the hell could be causing this. Only thing I've touched on the bike since it ran good, was the PV, and the spark plugs.

I filled up again yesterday, so I doubt it's bad fuel. Both plugs are gapped to .40, I do recall dropping one of the plugs the other day. Had to regap it, is there anyway this could of done damage to the pluf that would cause this?

What seems the most strange to me is, yesterday it only did this until it was hot... What problem could be temperature related?

Any help would be appreciated, I'm kind of freaked out here, 2010 sportster with only 3000kms running like junk!

 

This sounds IDENTICAL to what mine did a while back. I ended up bringing it to the dealership and they said the ECM was shot. No matter what tune they loaded it ran EXACTLY the same. Mine had the exact characteristics, word for word.

 

For some reason it sounds like a plug, or a wire arching out. Id change the plugs and get a set of wires. Atleast thats wht it sounds like to me.

 

No offence, but I hope you're wrong. I cant imagine thats a cheap fix...

 

Mine was under warranty when it happened, thankfully. Hope for your sake I'm wrong.


Here's the link to the thread I had posted about it. I deleted the pics of my plugs from my photobucket long ago but they were in bad shape. It was originally suspected to be a Power Commander issue but after trying a new Power Commander and also trying a Super Tuner with the exact same results it was eventually traced back to the ECM.

https://www.hdforums.com/forum/sport...nder-junk.html

 

Had that happen once to me. The power to the tuner had gotten pinched in a riser change. Taking care of that made the bike run as it should.

 

Thanks for the feedback, I'm wondering if it's maybe a bad connection at the plug wire... But wouldnt it run crappy the entire time? I'm confused why it's only running like this until the engine reaches normal operating temp.

I'll swap out the plugs anyways and ensure there's no pinch points on the PV data cable. I'll also check for any stored DTC's in the ECM.

Hopefully it's that easy of a fix... I'm not sure if there's any warranty on my bike, the PO didnt mention any sort of trasnsferable warranty when I bought the bike. It has under 5000km's, 2yrs old, is there some sort of base factroy warranty?

 

Doesn't sound like anything with the tune. I've read your posts in the PV thread on XL and you seem to have a good handle on it.

I'd check/replace the plugs and plug wires and go from there.

 

I picked up a set of plugs on my way from work... double checked the plug cables. Gaped them, popped em' in, loaded the initial FuelMoto tune just to be sure... fired her up and she purrr'd like a kitten. Went for a quick ride and all is well. Thank God it was that simple, must of been a cracked insulator on a plug or something, nothing I can see with my eye though.

Regardless it's running again, and thats all that matters!

 

My 883 started doing that to me a couple days ago and after I killed the ignition it wouldn't start back up. Since it was an old battery I purchased a new battery and cleaned all connections before installing it. It fired right up but is still sluggish and hiccuping. The difference between my problem and yours is that mine did not go away after the bike warmed up.

Do you think new spark plugs could fix this problem as well or is it something more major?