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Searching for a gremlin?


I have a 2013 C 14, and I’ve done some recent upgrades to you. The bike has picked up a weird habit of idling extremely low when cold. It will start up and barely idle at 600 or so RPM. After a few miles of riding in a come to a stop, the idle is about 1200 RPM. I am wondering if anyone has any insight as to why it would idle low, after sitting overnight, then after it warms up it idles normally. Looking for some insight as to where I start looking for the potential cause. Thank you all for your insights and feedback, this is a great group with extensive knowledge.


The factory service manual states the following:
"Much of the DFI system troubleshooting work consists of confirming continuity of the wiring"
It goes on - later - to list at least 10 possible sources (components) that should be checked as a possible cause of unstable or rough idling. The list includes air & water temp sensors, fuel and atmosphere pressure sensors and various mechanical (position) sensors.
I'd start with the manual.
Or, you could reverse each of the recent upgrades to see if any are the culprit.


Justin what upgrades have you done - anything recently that would muck with vacuum? How many miles on the bike? Ever change the fuel filter? Last air filter change? Any other changes or performance issues?

Bagger John

How many miles on the bike since the last valve adjustment/throttle body sync performed?


When did you begin to notice the issue? Did it come on gradually or start all at once?

FWIW, my '12 (15k mi) does this when cold but after a warmup period that gets 1 bar showing on the temp gauge, the idle speed picks up to 1k.


I'd bet a fiver it's the water temp sensor.
When mine firsts starts it smells a bit rich, does yours? Then goes away as it should.
2014 C-14