M1100 Evo Very High Idle after Flat Battery

[Nokka18]

Hi all,

I know there are many posts regarding high idle speeds but I haven't been able to find anything that matches my situation.
I have a 2013 Monster 1100 Evo with about 16000 kms on the clock. I replaced the original battery with a LiFePo battery about two years ago which worked fine until I left the bike un-ridden for a couple of months without a trickle charger. I charged the battery using a Victron charger (set to Li mode) and it started and ran with no problems. After a short ride and a few minutes with the bike turned off, I tried to start it and the battery was pretty much dead - the engine would basically turn a single revolution and not start. I couldn't bump start it due to the high compression and the location (no hills & no-one to push) so I persisted cranking and, after a half-dozen or so attempts, surprisingly it started. The problem was that the idle went straight to about 3000 rpm and stayed there. I suspected some sort of ECU issue due to the state of the battery and the multiple start attempts. I rode it home and did some Googling and the only suggestion I could find was to turn the ignition on, wait until the instruments go through their initialisation sequence, turn it off without attempting to start the bike and repeat this process several times (presumably to 'reset' the ECU). I did this, along with replacing the Li battery with an OEM-equivalent sealed lead acid battery, but the problem remains. When I start the bike it immediately idles at 3000+ rpm.
I know there are many potential causes of a high idle speed but the fact that it had been perfect until the battery/starting issue and then immediately went and stayed super high seems to suggest some sort of ECU or other electrical issue.
Any ideas? Any help would be greatly appreciated. Thanks.

[ducpainter]

I agree your high idle issue isn't from the typical causes, ie a vacuum leak.

Low voltage can wreak havoc on electronics. It's possible the ecu was damaged, the software corrupted, or a sensor failed.

If you don't have some sort of diagnostic equipment you're going to need to get it to someone that does.

[Howie]

Or you could use the shogun method if you like wasted work and money.  Check for vacuum leaks. then adjust idle speed, set CO and synch.  Still no good, most likely the idle speed motor