Is it the lambda sensor?

[denny]

For info here's a little background...my '03 1150 has been stored in a garage with battery removed (on optimate) for the past couple of months. Prior to this the bike was running perfectly (standard) with nothing other than an Akrap can.

I picked up a Remus y piece in the meantime and got round to fitting it last week, which is when I also slotted the battery back in. Tried it with the Akrap...was nice but not for me, so removed it the next day. I noted the throttle cable thing had slipped out after lifting the tank so I slotted that back in place. Anyway...since then I've used the old girl half a dozen times & have noticed that she stalls every so often. Sometimes after starting her up while putting gloves/lid/case on and sometimes when pulling up somewhere and pulling in the clutch. It's like she's running fine, but all of a sudden the idle drops a little and she stalls...sometimes she managed to pick herself up again though.

I've read through previous posts, like water in the tank...yes I washed her thoroughly last week, but that wasn't the first time for her. Checked that throttle cable...was in place. Did the motronics (sp?) ECU reset, despite Steptoe's advice not to bother...no change. Don't know where any of the other sensor are. I'm guessing it's the lambda sensor? I fecked a sensor on my 306gti many moons ago & had similar problems. Must say though I was very careful when removing and fitting the sensor when changing to y piece & back again.

Grateful for any feedback

 

[Uncle Crumpet]

every fault or issue I have had with any bike AFTER I have changed or modified something has always been due to something I did or didnt do.They dont catch a disease while your not looking, retrace your steps and you'll find it.

 

[uncle dick]

Very unlikely to be lambda sensor as the engine will be running open loop under the conditions you describe.

Dick

 

[uncle dick]

Has it had fresh petrol since being laid up?

 

[DrAlf]

Agreed. 03 could be twin spark and therefore far more likely to be coil packs – known point of failure. Could also be ECU or air leaks around the throttle bodies – check the little rubber balance caps. Why do you think it’s the lamda that’s failed?

 

[denny]

Has it had fresh petrol since being laid up?

It had less than 1/4 tank while sat in the garage. Filled her up the other day.

Agreed. 03 could be twin spark and therefore far more likely to be coil packs – known point of failure. Could also be ECU or air leaks around the throttle bodies – check the little rubber balance caps. Why do you think it’s the lamda that’s failed?

ECU's scare me!! I had one go on my XT660X last year...was not a cheap fix! I initially thought it was the lambda sensor as that was the only part of the bike that I fiddled with prior to her going silly on me...that and removing the battery of course. Are the throttle bodies/rubber balance caps easy to access?

 

[MattW]

It had less than 1/4 tank while sat in the garage. Filled her up the other day.



ECU's scare me!! I had one go on my XT660X last year...was not a cheap fix! I initially thought it was the lambda sensor as that was the only part of the bike that I fiddled with prior to her going silly on me...that and removing the battery of course. Are the throttle bodies/rubber balance caps easy to access?

The throttle bodies (TB's) are sticking out in the fresh air on the inlet side of each cylinder (the bunch of stuff on the other side of the cylinder to the exhausts). Look on the underneath of the TB's and you should see a little rubber cap on a 3mm or so diameter brass stub (used to connect vacuum gauges for balancing). If you see a little brass stub rather than a rubber 'nipple' (for want of a better word) then the cap is missing. If you do find one missing, they are cheap to buy from a dealer or other BMW parts supplier but in the meantime you could bodge something to fit (I used a short length of PVC tube that was a good fit on the stub with its open end sealed with a suitable screw).

You can test for other air leaks by spraying carb cleaner around each TB with the engine running. If it speeds up there's an air leak. However be careful you don't spray it into the airbox air inlet (the black plastic snorkel under the left lobe of the fuel tank) - this will also make the engine speed up and might confuse the issue.

 

[denny]

MattW, nipples are present and pert! I've not got any carb cleaner...is it anything like brake cleaner?

Thanks
denny

 

[MattW]

MattW, nipples are present and pert! I've not got any carb cleaner...is it anything like brake cleaner?

Thanks
denny

Glad your nipples are present and correct!

Brake cleaner is just fine

 

[monkeyboy]

Could be the lambda - I'd rode my 1150GSA for 20k on a trip abroad, all fine, road it back from the freighters, all fine. Left it in the garage for 3 months then started riding it regularly again and it was an absolute BITCH. Stalling, stuttering, really flat and horrible especially about 3k, revs would just drop to nothing on clutch in. It was a really inconsistent though and an absolute pain. I changed the lambda (for the third time!) and it was a different bike. Not to say it definately is in your case but when they start fecking about they really make the bike act strangely in my experience. Others are probably right though - it usually is something to do with something you've done. I'm not sure if the electronics are in any way capable of 'learning' and adjusting for a change (like the exhaust) and it might just sort itself out after a bit more riding.

 

[Steptoe]

Agreed. 03 could be twin spark and therefore far more likely to be coil packs – known point of failure.

+1 main plug coil caps

Easy to check - Plenty of threads on how to check them.

 

[denny]

Thanks for the replys, will check the coilpacks tmrw hopefully.

Bit more info, early this morning 20minute ride to drop the Mrs off bike was sweet...filled the near empty tank & 15 minute ride later alls still good. Meet up with pals & we're off. 15 minutes into ride (motorway) the revs totally drop but engine keeps running...I could hear the engine possibly misfiring kind of like a bupbupbupbup noise (revs still at zero though). All of a sudden revs back on and engine running fine. This happend once again about 30kms later. Started to get worried at this point.

Anyway...the problem didn't happen again until about 300kms later. Just the once, but quite worrying as it was just after I came out of a mountain pass giving it beans! Didn't happen again & the bike didn't stall all day.

So I initially thought it was dodgy fuel, but seeing as I filled the tank at a station I always use it must be something else. Do these signs also point in coil pack direction?

Cheers
Denny

 

[denny]

Found threads which recommending checks on the coil packs, but none of them actually detailed how it's done. Grateful if someone could give a quick rundown on how it's done.

Thanks
Denny

 

[MattW]

the revs totally drop but engine keeps running...I could hear the engine possibly misfiring kind of like a bupbupbupbup noise (revs still at zero though). All of a sudden revs back on and engine running fine. This happend once again about 30kms later.

Tacho misbehaving and running problems when hot can be a symptom of hall sensor failure.

 

[denny]

Tacho misbehaving and running problems when hot can be a symptom of hall sensor failure.

Previous posts give me the impression that the hall sensor is linked to the coil packs?

If either of these were to blame what are the chances that they would leave me stranded roadside? I'm planning on riding approx 2000kms next week down to the south coast & back with the Mrs over the easter break, really don't want to be fidling around with tow trucks & the like!

 

[MattW]

Previous posts give me the impression that the hall sensor is linked to the coil packs?

If either of these were to blame what are the chances that they would leave me stranded roadside? I'm planning on riding approx 2000kms next week down to the south coast & back with the Mrs over the easter break, really don't want to be fidling around with tow trucks & the like!

Coil packs and the hall sensor are both ignition related. The hall sensor provides the timing pulse that the ECU uses to trigger the ignition and fuel injection. It sits behind the pulley on the front of the crankshaft (behind the plastic cover at the front of the engine).

I've not got a twin spark bike so I've no experience of diagnosing problems with them but I'd guess that a coil failure could strand you. Hall sensor failure definitely would... It's not hard to change a hall sensor plate but I wouldn't fancy doing it at the side of the road - it takes a a bit of getting to and you'd need the right tools with you. I'd imagine a coil is easy. Unfortunately the hall sensor plate is not cheap (not sure about the coil).

That said, your problem might not be the hall sensor at all but some of the symptoms you post suggest it as a 'possible'. Hopefully someone will post with some ideas about how you can diagnose it properly.

 

[Steptoe]

Previous posts give me the impression that the hall sensor is linked to the coil packs?

If either of these were to blame what are the chances that they would leave me stranded roadside? I'm planning on riding approx 2000kms next week down to the south coast & back with the Mrs over the easter break, really don't want to be fidling around with tow trucks & the like!

Hall sensor and main plug coil caps problems are not linked.


To check the coil cap (main spark plug cap), pull off the lower secondary spark plug caps from the spark plugs, then see if the bike runs on just the main plugs. If it only fires on one side or doesn't run at all you've found the problem.

 

[denny]

Steptoe, do you mean these caps (circled)? The manual states a special puller is needed. I've not checked them close up, is it possible to improvise?

 

[Steptoe]

Steptoe, do you mean these caps (circled)? The manual states a special puller is needed. I've not checked them close up, is it possible to improvise?

The puller should be in your tool kit. If not use two flat bladed screwdrivers. But for testing you don't need to remove the main caps, just the lower caps...

If you can't figure out how to pull the spark plug caps off, put the tools down and step away from the bike....

 

[foxy2000]

Thanks for the replys, will check the coilpacks tmrw hopefully.

Bit more info, early this morning 20minute ride to drop the Mrs off bike was sweet...filled the near empty tank & 15 minute ride later alls still good. Meet up with pals & we're off. 15 minutes into ride (motorway) the revs totally drop but engine keeps running...I could hear the engine possibly misfiring kind of like a bupbupbupbup noise (revs still at zero though). All of a sudden revs back on and engine running fine. This happend once again about 30kms later. Started to get worried at this point.

Anyway...the problem didn't happen again until about 300kms later. Just the once, but quite worrying as it was just after I came out of a mountain pass giving it beans! Didn't happen again & the bike didn't stall all day.

So I initially thought it was dodgy fuel, but seeing as I filled the tank at a station I always use it must be something else. Do these signs also point in coil pack direction?

Cheers
Denny

Had a similar problem with general misfire and dying under load on motorway for a few seconds. Was faulty coil and Lambda sensor on one side. Took plug out and it was sooty on the dodgy side. Coil didnt look corroded. Sensor was sooty. Changed both - new sensor and used coil. Sorted.
Foxy