So I've got a 2016 Iron 883, and I put on V&H Staggered Short Shots, a K&N Air charger intake, and an FP3 tuner. Did all the work myself, so I don't really have anyone to turn to for help.
Ran the canned map provided for my setup in the FP3 app for a day or two, and the bike ran like crap. Bogged down when taking off from a stop, making a coughing sneezing kind of noise out of the air filter. So I promptly began the autotune process. During the autotune, the bike ran even worse, but I stuck it out for about 2 weeks, as I read that this was par for the course. After autotune, the bike ran great, especially my top end. Where I used to feel like I was pushing the bike to maintain freeway speeds, now I basically live at about 70mph, and do it comfortably.
Everything has been great, except for one problem. When cold, the bike starts great. Occasionally it'll start to turn, make that sneezing noise out of the air filter, and then fire up, but most of the time it turns right over and runs great. However, if I get the engine good and hot, and not just riding a few blocks to the gas station, but riding 4 or 5 miles on the freeway, when I shut it off and try to restart it, it sputters and runs like crap. I have to sit there and give it a little gas to keep it running. Sometimes it sputters out a couple little poofs of smoke out the exhaust too, when it first starts. Then for the first couple miles of my ride it idles REALLY high. Like, 1500 rpm. Finally after a bit it settles down and runs fine, although I do feel like it doesn't have quite as much power after this second start up, until I stop and let the engine cool down for a couple hours.
All this leads me to believe it's running rich, but only after shutting off the bike, and restarting it before letting it cool down completely. It's almost like the ECM is going through its whole warm up enrichment process, even though the engine is already warm.
So, of course, I start tinkering in FP3, and I drop the cranking fuel by 2 ms across the board (a tip I read on this forum). Seems to help a bit, but didn't fix the problem. Drop it one more ms, and the bike won't even start when the engine is hot. I have to try a good 3-4 times to get it to start. Drop the warm up enrichment by .2 across the board, same thing. Won't start when the engine's hot.
What do I do?! Any ideas?? I feel like I'm running a pretty common setup here, someone else has to have experienced this before? I'm worried that if I tinker too much I'm going to blow the thing up!! Haha.
Thanks for reading, I look forward to your replies.

 

A quick install check is to verify the black connector O2 connector leads to the rear cylinder.
I know it is an issue with touring bikes and not sure you can get them backwards on current Sportsters due to where they are installed.
Worth a check, right?
Bob

 

Re Load the stock calibration disconnect FP3 and see how the bike will perform, if the problem stopped batter that you look for dyno tuner that aware/knowledgable how to work with FP.

 

I agree with Bob, sounds like the O2 sensors may be crossed. Easy to do and does exactly as you describe.

 

First of all, thank you everyone for your quick responses!
I'm not sure how I could've gotten the O2 sensors wrong though... I'm almost positive that the connection for the front O2 sensor was on the front of the bike, in front of the engine, and the connection for the rear O2 sensor was under the side panel, kind of by the battery under the seat. On top of that, if I remember right, the cord for the front O2 sensor was significantly longer, while the rear O2 sensor had a short cord. Therefore, each O2 sensor would only be able to reach the socket that it was intended to be plugged in to. Plus, I feel like my bike would be throwing codes for this, but there are no codes present in the FP3 app, nor has the check engine light been on at all. Of course, I could be wrong about this, so I'll check it out tomorrow.