Recently took a trip from the Oakland Ca Bay Area to Street vibrations. Upon arriving in Reno my 98 ultra classic with fuel injection and a power commander started running strange (idle would drop down to say 500 rpms and then I would turn it off and restart it and it would race at say 1700 rpm. Through all this it ran really good but idled strange. Upon returning home I put the bike away, and attempted to start it the next day and it had a hard time starting and once it started it was running on what seemed to be one cylinder at times then both cylinders very erratically. I tried new plug wires and checked battery connections as well as inspecting the spark plugs but still having the same problems. Any ideas what this could be?

 

Remove the power commander and go directly to the stock ECM and see if it works right. If so you may have a bad PC III.

 

Had that happen to my '00 and it was bad fuel. Seems my M-M EFI doesn't like the blend of BP gas around here.

Not saying that's it, just been my experience

 

Tried removing the power commander and no change.

 

A friend had a similar problem. turns out it was the TBI position sensor

 

Check your headers for tight fit or cracks. Block the exhaust at the back of the bike and check for leaks.