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Steve
Steve, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 6880
Experience:  30+ yrs. experience, MMI, HD technician, HD early, engine rebuild/performance, bike builder, kit bike program manager, CCI 2001-2004
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I have an EFI issue with a 98 Ultra Classic. When warm it shoots

Customer Question

I have an EFI issue with a 98 Ultra Classic. When warm it shoots flames out the right side on decel. Engine light comes on when throttle is released. The fuel ignition in the exhaust sounds like a very loud backfire. I bought a power commander, but it doesn't work with the replacement ecm that is in the bike. I tried buying a used ecm for the same bike and it doesn't fire with or without the power commander hooked up. After putting that ecm in and reinstalling the first one, it doesn't want to stay running and the engine light is on when im not on the throttle. Ideas? Could I have messed up the ecms by not disconnecting the battery when i put them in?
Submitted: 1 year ago.
Category: Motorcycle
Expert:  Steve replied 1 year ago.
first, everything comes out the right side. the left side is for show.- flames and/or popping out the exhaust during decel can be caused by loose or leaking exhaust gaskets.- if your exhaust gaskets are good and tight, it indicates the IDLE portion of your fuel map being too rich......HOT, unburned fuel from combustion travels down the exhaust pipe at super sonic speeds and when it contacts fresh air, it utilizes the O2 in the air to complete the combustion process......BANG.- you should have your ECM diagnostic codes read by a HD dealership with a scanalyzer.- that said......if everything was good and then this just started happening, it is most likely due to low compression or a failing engine temperature sensor.let me know if you need more help.Steve