Sluggish Idle after bike heats up...

KDog Bone

.040 Over
Joined
Jul 18, 2016
Messages
52
Location
Oakville, ON
Ride
2013 Triumph Rocket III Roadster
Hello,

I recently bought a 2013 R3R (used) and have been having a blast!

The other night I was out for a ride when very early on the check engine warning light came on (Engine Management System Malfunction Indicator Light).

I returned home quickly and turned the bike off and let it cool off. when I restarted it, the light came on again, but the third time I tried it did not come on. I tried going for a ride again, but I found that the idle was very sluggish, almost wanting to stall unless I gave it some throttle.

I tried again the next night, and things started fine, no warning light, and I went out for a ride, but I felt like the bike was not as powerful as I am used to. Once it heated up, the same issue started again with the idle. No other issues, other than that.

My question is: In the manual, it refers to a "Limp-home" mode that the bike goes into if the ECM MIL comes on. Could it be that this mode is still enabled, even though the fault has cleared from the system and the warning light is no longer coming on?

No mods except a K&N TB-2204, which has been on for a week (4 hours of riding) with no issues... until now.

Thanks!
 
Hang in there mate, the blokes with the knowledge will be here soon
 
Kdog, do you access to a OBD2 dongle or TuneECU cable? If not, you've got to find some way of reading the code that's been triggered.

Guessing you've got a bad TPS or IACV.
 
I have one on order from London Electric for Tune ECU, but it will be a couple of weeks before it gets here. I have the shop manual, but it is not much help without the cable!

I have an apt with a dealer late next week, but figured I would see if there was anything I could do in the meantime. Thanks for the message!
 
I wouldn't advise messing with any of the sensors without being able to read their voltages in TuneECU so you can verify they are installed correctly.

Very interested in what the dealer reports back!
 
The dealer will probably change the abs sensor, charge him a small fortune and send him on his way!!! Then tell him we have never seen a problem like this before!! After keeping it for two weeks to boot!!
 
So I borrowed a code reader and found out the error code is P0638. Second throttle aviator motor / wiring fault. I have done a quick check on this forum but need to look some more. The engine runs but once warmed the idle is still rough. Mil has NOT come on again, so maybe it is just a tune issue related to the air filter replacement? Fingers crossed. I will ride again today.
 
Well if it has to do with the "Second throttle aviator motor / wiring fault" I would guess what is happening is the secondary throttle plates are closing and opening incorrectly. Just a wild guess. I've completely removed the secondary plates on my bike so if you do that I bet it will run heck of lot better.
 

Thanks. What was involved with that fix? I found a video on this forum talking about it but was not clear on how big a job it is? I rode today and still have the same performance. Runs like a 450 nota 2300...
 
I'd not remove secondaries. I just put mine back in today after a long time without them, zero change in the 3600-7000 full throttle fueling requires to ride the perfect AFR, meaning they aren't a significant restriction when fully open.

Your problem isn't a tune issue or ecu issue, it'll be something with the stepper motor or the secondary throttle position sensor, until those are fixed, it may be running sluggish, because it may just be leaving the secondary throttles closed (it still lets some air by, 0% secondary setting still has a healthy crack to allow some air to flow).

I DID find at lower RPM, sub 2400, having them at a partially open position helped throttle response. Something similar to the below, but I use Tuneboy:

 
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