I have a 2001 fatboy fuel injected twin cam 88b...... I just installed a set of badlands saber digital mirrors when I did this I did not hook the wire from the speed sensor going back to ecm up will it affect how the bike runs? the rear jug is miss firing now and it is dropping to 600 rpms when coming to a stop a has died once. Should I start with the wire or look at something else?

 

Maybe I'm missing something....

The bike ran fine, you disconnected the speed sensor, it is now running poorly, and you wonder if you should wire it back the way it was?????

 

Yes and no the bike had other problems when I bought it causing vibrations and poor handling..... the miss developed after about 700 miles of riding after I fixed the other issues.... the low idle did just happen immediately it strated after a 100 miles of riding

 

Sounds like you have several issues.... I thought you made a change, and then a new problem appeared.

Generally speaking, if something new pops up after I have worked on my bikes, I suspect it's because of something related to what I just touched, changed, "fixed" or disturbed... I always start there...

But to answer part of your first question:

The fuel injected bikes depend heavily on the ECM AND sensor feedback for the bike to run well. I would make sure all sensors are hooked up and operating properly. A bad/disconnected sensor can cause many issues.. The caveat being some tunes/tuners will allow the removal of the exhaust O2 sensors.

Good luck..