[JamieTheGiraffe]

I have a very similar problem on my '05 with a short pipe. Runs very nicely throughout the range on a slightly richened TOD for early model S3's, but the idle often drops when you pull the clutch in after decelerating in gear to a stop sign/light. Happens at seemingly random times whether hot or cold.
It doesn't normally stall, but the idle will fall to 800-1000rpm then slowly climb its way up to ~1300 where it's supposed to be.
Just like Tilt here, my TB's are clean and balanced, TPS adjusted, properly adapted, plugs in good shape, cables adjusted properly, even cleaned up the stepper motor shaft and the TB's little roller arm thingy... not sure what else to try.

Oh, and my bike also used to surge/miss between 3500-4000 at steady throttle in low gears. Adding points to the F-trim table in that rev range under 15% throttle using tune ECU richened the mixture (as i understand it) and helped smooth that out.

 

[JamieTheGiraffe]

Thought I'd weigh in here again real quick for anyone experiencing similar idle woes on otherwise well sorted 1050's.
The solution to this specific "idle drops real low after rolling to a stop then climbs back up" problem for me was to pull the tank and airbox & clean the crap out of the stepper motor and it's little actuator arm. Parts cleaner/brake cleaner to get all the grime out, then re-lubricate with a dry teflon based lube.
This should totally be on the 12k service, but since it isn't us triumph slaves have to figure it out ourselves.
Hope this helps anyone with the same issue!

 

[JamieTheGiraffe]

Hey ya'll, wanted to report back in on this as the problem has returned. It was better for a while, but now it seems to randomly go through periods where the idle drops super low and almost stalls when you pull in the clutch. After a few seconds of idling low, it slowly climbs its way back up to normal idle rpm.

As far as I can tell, this issue is related to the throttle position sensor. I set mine to .60V, it does great for a while, then the problem returns, I check again, and the TPS voltage has usually gone up to something around .68V and that causes it to bike to idle low.
So the question is- why the **** does my TPS voltage keep changing? Obviously i'm tightening the sensor itself down well, and no it isn't cracked from being overtightened. Already learned about that the hard way...

Any help or suggestions would be appreciated.

Might be worth mentioning that this a well maintained 05 speedy that runs beautifully except for the intermittent sketchy idle.

 

[JamieTheGiraffe]

Yep, sounds like we are in the same boat for sure. For whatever it's worth, I did a full head gasket job a few months ago and set all valves to dead middle of the spec range upon reassembly, so I doubt it's that.
I too have fresh oil, clean air filter, clean throttle bodies, good plugs, etc.
If the damn TPS voltage would just stay put the bike would be perfect!

 

[JamieTheGiraffe]

Yesterday I reset the TPS and double checked the clearance between the stepper arm and throttle cable pulley thing. All good. I adjust the TPS with the tank and air box removed as per the instructions.
After reassembly and readaptation, the low idle intermittently persists. Seems like the bikes prefers to have the TPS voltage set when it's completely assembled (using a 7mm box wrench for the screw behind the frame). But that solution still doesn't tell me why the TPS baseline voltage keeps changing on its own. I'm getting really frustrated with this shit. It's been going on for months now and it makes me want to throw my speedy in the drink. Or just sell it.