Engine cutting out

[Standby diver]

Long time no talk fellow S10 people. I need some help with my bike, I've been having some issues with the engine cutting out.

2012 S10 with 56k miles that occasionally idles very low at stops <900rpms and has died completely when shifting gears. The engine has died completely while up shifting at highway speeds about 3 times and is able to be bump started immediatly after. Recently the bike died while going slower, downshifting from 3rd to 2rd, bump started again and ran fine.
Put the bike in diagnostic mode.
D:01- 09
D:14 - low 17 high 101
D:15 - low 17 high 100
While on the stand I was running the bike and notice that if i gave a super small throttle input the RPMs would drop below 1K and lug really bad. If I continued to give throttle the engine would increase RPM and run fine. However, if I gave a couple small inputs in a row I could get the engine to cut out.

I run high octane fuel only and dont use a fuel additive often enough (I am starting now maybe help with the issue.)
The bike is my commuter and does 46 miles of highway riding a day.
@ 47k Gen II CCT install, new plugs (OEM), valves checked and adjusted, oil and filter changed, air filter changed (OEM)
@ 49k New battery (OEM)
@ 52k Oil changed, final drive oil changed
@ 55k throttle body sync

any help troubleshooting this issue would be greatly appreciated.

 

[BaldKnob]

Has this machine had the wiring harness recall performed? Low, hanging idle or randomly shutting off seems like it may be related to a shorting of the system.

 

[Jlq1969]

D14 and D15, are the 2 throttle position sensors, one for the wire, the other for the accelerated idle in cold start / cruise control .... through the electric engine.

but first check that the synchronization plugs are well placed

 

[Standby diver]

I was searching my VIN on the NHTSA website which said my bike wasn't part of any recall, hence reaching out on the forum. But I just searched my VIN on yamaha and sure enough it is part of the wire harness recall and it has not been completed.
I was tinkering around with the bike again and was unable to get the low throttle input and drop in RPM issue to occur again. The intermittent nature of this problem to me suggests electrical. So fingers crossed a new wire harness solves the issue.

 

[HeliMark]

In addition the getting the recall done, I would also go through the electrical connections and make make sure they are clean. As you know, the bike is sensitive to the electrical system.

 

[EricV]

We often create our own problems. Look hard at that last thing done, the throttle body sync. Did you do this yourself, or have it done?

If you had it done, a lot of things could have been altered. Check that the vacuum cap is in place on the throttle side TB and that the hose is in place on the clutch side TB.

If you did it yourself, did you do anything to the painted screw?

This bike has no idle adjustment. If it's off, that's often an indication that the idle air flow is off. Do a search on throttle body balancing or syncing and read through some of those posts. I think a good one is a sticky too, look for that first.

 

[Standby diver]

Before putting the bike back together last night I checked as many connections as possible, they all seemed to be in good shape. I grabbed every bit of wire harness I could and moved them to see if I could get the idle to dip down, nothing, idled at 1100 rpm the whole time. I have no idea why the bike would drop RPM's with a small throttle input yesterday and have not been able to replicate the issue since. I haven't changed anything, besides removing the air box to get at more electrical connections, and take a peek at the intake valves. Valves had some fouling but nothing crazy.

About 30k miles ago I backed the painted screw out 3/4 turn to help with the off idle stumble as recommended on this forum, which was helpful. The most recent throttle body sync was to verify sync in an effort to troubleshoot the idling issue. But they were still in sync so no changes made. vacuum caps are in good shape. So the throttle body sync was done after the problem arose.

I am aware the bike has no idle adjustment. 99% of the time the bike idles fine at 1100RPM, but every once in a while it dips down to <900 as i said before. Even more rare the bike dies when shifting.

Edit: to be clear I do all the work myself.

 

[OldRider]

I had some similar problem, especially the high idle. Start and die, idle high, pull up to a stop light and just die, etc, etc. My problem turned out to be the battery. It would start, but the battery was so weak that it was taking everything it had to turn the engine over and the low voltage was screwing with the ecm. I put a new battery in and all the problems went away instantly. JMO

 

[Jlq1969]

Before putting the bike back together last night I checked as many connections as possible, they all seemed to be in good shape. I grabbed every bit of wire harness I could and moved them to see if I could get the idle to dip down, nothing, idled at 1100 rpm the whole time. I have no idea why the bike would drop RPM's with a small throttle input yesterday and have not been able to replicate the issue since. I haven't changed anything, besides removing the air box to get at more electrical connections, and take a peek at the intake valves. Valves had some fouling but nothing crazy.

About 30k miles ago I backed the painted screw out 3/4 turn to help with the off idle stumble as recommended on this forum, which was helpful. The most recent throttle body sync was to verify sync in an effort to troubleshoot the idling issue. But they were still in sync so no changes made. vacuum caps are in good shape. So the throttle body sync was done after the problem arose.

I am aware the bike has no idle adjustment. 99% of the time the bike idles fine at 1100RPM, but every once in a while it dips down to <900 as i said before. Even more rare the bike dies when shifting.

Edit: to be clear I do all the work myself.

The position sensors, have a small slide, are not fixed. Maybe they are with little tightening. or you have wear / bad contact inside them and there is no good position reading. If you move a little, taking advantage of the slide, you can accelerate it a bit and see if the fault continues

That sometimes the idle is 900, and that other times it stops when you engage gear, they may not be part of the same cause, the idle is a problem, the stop is other such as a defective side stand switch or the wiring of this