sorry if this new thread is already out there but i'm on day 4 of troubleshooting and i'm pulling my hair out. BTW i'm a new registered user here. been reading the posts for a year or two just never joined. anyway, i've got a 2008 ultra classic that won't idle correctly. bike has 19,640 miles stock 96" with hooker tuned flow slip on's, arlen ness big sucker II, PC III usb. bike was running fine then dropped to what seemed like 1 cylinder. limped home, no DTC. re-started and was fine for 10-12 sec then coughed, sputtered and died. re-started, same thing, seemed like it was coughing/sucking, rpm's were erratic, would dip down to around 800, cough, sputter then die. still no DTC. i removed the PC III and reconnected the O2 sensors, still had the issue. replaced the crank position sensor, still had the issue. replaced spark plugs and wires, still had the issue. reset throttle position, still had issue. cleaned MAP sensor and all other sensors/connectors, still had issue. checked all fuses, drained fuel and replaced with fresh, still had issue. re-installed PC III and re-loaded map, still won't idle. my local HD dealer has no new MAP sensors in stock. i have checked all wiring and grounds. any assistance would be greatly appreciated. thanks.

 

Battery connections?

 

What voltage is your battery giving? There are a couple of stickies in the Tech Electrical section you should refer to, to check the state of your battery and charging system. If you are down on volts then all manner of strange things can happen, also if you are getting very high volts.

 

Not sure on 08's but my 07 occasionally has idle issue, its the IAC motor, there's a thread or two on this issue. Most times you can clean it by removing AC, look up into the throttle body and on inside top about 1/2" in is a hole, turn on ignition and while spraying carb cleaner into the hole turn run/stop switch off/on several times. Make sure to place towel or other cloth under throttle body to catch carb spray run off so it doesn't get on motor and other parts. Worth a try.. BTW, IAC is Idle Air Control solenoid, worst case is replacement.

 

Funny now that you mention it grbrown, the battery voltage was high. Metered at 15.5-16.8 volts with the bike off and ignition off. nevets61, 08's have a MAP sensor in place of the IAC on top of the throttle body, or as HD calls it the fuel induction module. i removed it and cleaned it thoroughly with sensor cleaner.

 

My 07 got to where it would not idle. After eliminating all possible problems I talked to the service writer at the dealership. He said it was likely the throttle position sensor. I got the book out and did the test. It checked out good. But in order to attach the test leads to the wires I had to unplug the wires from the sensor. After plugging the wires back in and performing the test the bike runs and idles perfect. The only conclusion I could come up with was a bad connection.

 

07 and 08 have iac and tps issues.there is an older very long thread in here "07 idol issues".

 

My 08 classic did it several times over the summer, the solution is to cycle the power switch and the on off switch 3 times without starting it, puts it right into proper idle.