Who knows about BMW K1300S idle issues?

[waddycall]

Anyone on here familiar with this bike and it’s idle issues? A mate of mine has one. He loves it to bits but it’s been back to the BMW dealer many times to try and cure an intermittent rough idle/stalling issue. They’ve interrogated all the electronics and found no sensor issues, replaced the idle air control valve and hoses and done a few other bits and pieces but mainly head scratching. They suggested last time that the coils might be the issue but now believe it’s not as it’s now Idling faster although it’s not been adjusted. I reckon they may have trapped a cable when putting it back together.
Anyway if anyone has in depth knowledge of these it would be good to hear from you

Oh and my mate has tried numerous BMW forums/facebook but not got anywhere

 

[ajlelectronics]

The air intake flexibles after the throttle bodies are known for gently cracking up and admitting air. It needs a bit of work to get to them and dismantling to see their actual condition.

 

[waddycall]

The air intake flexibles after the throttle bodies are known for gently cracking up and admitting air. It needs a bit of work to get to them and dismantling to see their actual condition.

That’s interesting - maybe them breaking down could account for an increase in idle speed?

 

[Nomad]

Idle related but not BMW, I've had a problem with my 90s Alfa come back 3 times since I got it 3 years ago. At tickover the revs drop under 1k then it revs up to 2+ then drops back under 1k .. and repeat. Sounds like a boy racer blipping the throttle when your're stopped at the lights.

First time it happened just after I hit a pothole at walking pace and grounded the exhaust so I removed the exhaust and resealed the leaking joint - problem went away which made me think exhaust leak or lambda related. Next time that didn't work so I removed all the intake pipes and sensors - found no problems - cleaned everything - called a local mechanic who repeated what I'd just done then apologised saying he couldn't find the fault. The car started working before he left my driveway ! This time I checked the wiring to all the intake sensors (MAF, vacuum sensor, idle control valve / ICV) removed sensors and used lots of brake cleaner - I'm still not 100% sure but cleaning the manifold after removing the ICV seemed to be the thing that got it working again - maybe some build up on the seat for the ICV ??

BMW (car) specific: I had a 2007 325i and they are notorious for using a thin wall plastic breather pipe that runs in the space between the manifold and the engine block, they go brittle over time and often fail out of sight, they often snap if the manifold needs to be removed..

Hope you find the fault, I'm now confident I can fix mine in minutes if the fault comes back but I'm still not sure what's causing it

 

[Keithmac]

Sometimes it's worth letting a good independent garage have a look, they work on a far greater number of different bikes and can add some ideas that the main dealers may not have thought of.

 

[ajlelectronics]

Sometimes it's worth letting a good independent garage have a look, they work on a far greater number of different bikes and can add some ideas that the main dealers may not have thought of.

Another excellent technical resource is here... https://www.bmwlt.com/forums/k1200lt.11/ although that is the LT section, the engines are very similar across the range. This cracked plastic coupler problem is often discussed.

 

[ajlelectronics]

That’s interesting - maybe them breaking down could account for an increase in idle speed?

Yes because any air admitted after the throttle bodies will not be controllable by them, leading to fast and or erratic idle speeds, as well as weak mixture throughout the range. I can't imagine that it would throw up a fault code, so the "spotty yoof wiv laptop" would be clueless.

 

[Guzrik]

Yes because any air admitted after the throttle bodies will not be controllable by them, leading to fast and or erratic idle speeds, as well as weak mixture throughout the range. I can't imagine that it would throw up a fault code, so the "spotty yoof wiv laptop" would be clueless.

Spraying it with brakecleaner while monitoring the idle speed should confirm it, I think?

 

[ajlelectronics]

Spraying it with brakecleaner while monitoring the idle speed should confirm it, I think?

Yes, that is my go to test on Scimitars.

 

[Ian X]

I only met leakage to air with idle problems not caused by gummed components, outside of failing sensors or servos. I spray the connections with ether, Easy Start or just lab ether in a spray bottle.
If the motor suddenly sounds keen to rev you have a leak. I own several Rotax engines, the "rubbers" on all of them are crap and do not like light, heat, cold, anything, probably even fuel.

 

[waddycall]

So it turns out that the dealers tried spraying brake cleaner around the throttle bodies and inlet rubbers but not found any leaks.

 

[Blobber]

Might be worth spending on something like this

Pardon our interruption...