Hey everyone. A friend of mine started having problems with his 05 Ultra. When you start the bike it will idle fine for about 15 seconds and then the rpms will start to drop to around 600 rpms, then jump back up, then go down again. Changed plugs, but it didn't help. Sprayed carb cleaner in the IAC, and that didn't help. The strange thing is when the rpms are above 2500 the bike runs fine, and it's not throwing any codes. Will be changing gas tomorrow, but if anyone can point me in the right direction it would be appreciated. Thanks

 

check out the TPS

 

possible intake leak

 

Had the same problem with my 09FLHTP,

dealer could not get me in for two weeks, indy's all said that it needed to be plugged into "digital tech" to find out.

I reset the ECM twice, second time solved the problem.

Turn ign. on for 10 seconds, off for 10 seconds, do this 5 times, 6th time start it up.

Try it and see if it helps, if not try it again later, could be I was too quick on the sequence.

Hope that this helps.

Dan B,
Central Ks.

 

Could be the IAC motor, TPS, or a fuel leak inside the tank--among other possibilities. This is hard to diagnose, but I would start by replacing the TPS. That the was cause of my idling problems as well as intermittent misfiring. There are a number of threads about this here, so do a search on "TPS" and then "IAC".

 

this is a throttle reset for fbw bikes won't help the early bikes

 

crank position sensor

 

All good possibilities...I'll throw one more possibility in there...fuel filter. Clogged fuel filters can cause some strange runability issues not only at idle, but also well above idle. Hope you find the problem. I would look at that TPS as well.

 

Is this happening when HOT? The first time my 06 dropped the idle down to 550-600, I was riding on a super hot day, and stuck in traffic. I found out the 06 models has HMS, a Heat Management System.

I did not stall, but it freaked me out. Here is info from the service manual

 

Just an up date, drained the gas tank and added injector cleaner, and swapped out the TPS. no help. Checked for air-intake leaks and found no problems there. I'm in the process of draining the tank again and will replace the hoses. Hope this does it cause I'm running out of ideas.