Cuts out when opening throttle - BMW Luxury Touring Community
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post #1 of 7 Old Feb 18th, 2017, 11:14 am Thread Starter
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Question Cuts out when opening throttle

Hey folks. I'm wondering if any of the LT experts here could give me some advice.

Following some work (see below), my bike idles ok, and if I open the throttle a good amount it revs/accelerates ok, but when the throttle is open just a small amount, the engine dies (in neutral) or all power is lost and the bike coasts until I either open or close the throttle a bit.
The first time, this started happening about 5 minutes into a ride, when I gunned the throttle to pick the bike up after I nearly dropped it doing a u-turn (!) and continued for the remainder of the 20 minutes or so I rode. I then left it for a week, fiddled with the cables and tried again, and it was fine for the 20-minute trip to the shops, but the fault was back when I started the bike up again for the return journey, so maybe it is linked to the engine being warm?

The GS911 shows the following 3 faults:

1285: Idle Regulator, Signal implausible
This fault occurred 160 times.
The fault is currently present.
5381: Idle Switch, Short-circuit to Positive or Open-circuit.
This fault occurred 17 times.
The fault is currently present.
5382: Idle Switch, open circuit since ignition ON.
This fault occurred 0 times.
The fault is currently present.
I wondered whether a dead-spot in the TPS might be to blame, but I watched the readout on the 911 whilst smoothly opening and closing the throttle, and it registered perfectly, from about 2.5 to 80something degrees.

Any clues as to what I should look at first?

Many thanks in advance.

Nick


--

The full story of the work done - The ABS unit failed, and whilst that was out and being repaired, I thought I'd take the opportunity to fit Spiegler brake lines. I guess I must have routed the new cable differently to the old one down the handlebar, as once everything was back together the cruise control wouldn't engage. I traced this to the throttle close line permanently holding the cruise control disconnect microswitch open. I initially attempted to loosen of the cable tension, but the cable sleeve itself was pulling on the microswitch housing, so instead I removed one of the small bolts holding the switch and rotated it back slightly more than the holes allowed. Now the cruise control engaged ok, and I could still disengage it by closing the throttle slightly. However, now the bike wouldn't start or idle when cold without me cracking open the throttle a bit. So I tightened up the cable tension again to where I thought it was before. Things were better, although it still needed a bit of throttle to start when cold, and it was at this point I went out for a test ride and the cutting-out issue started. Now I have removed the handlebar plastic, re-routed both cables around the brake line (though I'm not sure whether they are supposed to go under, over or whatever), cleaned up the adjuster nuts and set a couple of mm freeplay in the cables. For the ride to the shops this afternoon, I removed the ECU fuse for 15 minutes, then did the reset procedure (ign on, open/close x3, ign off, pause, on, start engine). I still needed to open the throttle slightly to get the engine to start, but then it ran ok, and for the 20 minute ride, all was silky smooth LT riding at its best, with cruise control engaging and disengaging ok, and no throttle dead-spots. Then, as I said, when I got back on the bike 20 minutes later, it was cutting out again, and I struggled home like a kangaroo.
Sadly, this bike has become one of those 'projects', where every bit of work to fix one thing seems to lead to another failure, and the bike never quite gets back to being fully serviceable. I hope I don't end up having to scrap it...
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post #2 of 7 Old Feb 18th, 2017, 7:40 pm
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Re: Cuts out when opening throttle

FWIW the throttle cables go over the brake line. Just changing the brake lines should not have caused an issue with the throttle cables so re-check your routing, making sure there is some slack in the cables and that they are not bound up by the brake lines. John (sailor) should chime in soon with his thoughts as he can interpret the GS-911 faults better than I can.

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post #3 of 7 Old Feb 18th, 2017, 9:03 pm
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Re: Cuts out when opening throttle

John is right about Sailor and interpreting the GS911 output. I do have a question. Did you unplug any of the cables on the left side around the throttle body? The idle regulator is likely the TVA and with the faults reporting as still present, Something is currently wrong. There is also a switch inside the TVA so that might account for the second fault. I would check the TVA plug to make sure it is seated properly. They don't go bad very often but there are a few reports of some failing. Your bike should start with no hand on the throttle if all is working properly.
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Gordon
Sugar Hill, GA
2001 K1200LTI – Champagne (current ride) Lazy Susan
1998 R1100RT – Never should have sold it
1974 Yamaha TX 750 Twin. Omni Phase Balanced


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post #4 of 7 Old Feb 19th, 2017, 7:38 am
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Re: Cuts out when opening throttle

Quote:
Originally Posted by jzeiler View Post
FWIW the throttle cables go over the brake line. Just changing the brake lines should not have caused an issue with the throttle cables so re-check your routing, making sure there is some slack in the cables and that they are not bound up by the brake lines. John (sailor) should chime in soon with his thoughts as he can interpret the GS-911 faults better than I can.
Quote:
Originally Posted by bmwcoolk1200 View Post
John is right about Sailor and interpreting the GS911 output. I do have a question. Did you unplug any of the cables on the left side around the throttle body? The idle regulator is likely the TVA and with the faults reporting as still present, Something is currently wrong. There is also a switch inside the TVA so that might account for the second fault. I would check the TVA plug to make sure it is seated properly. They don't go bad very often but there are a few reports of some failing. Your bike should start with no hand on the throttle if all is working properly.
In my opinion, John and Gordon are both correct in their message above... AND it also shows that these SPECIFICS GS911 faults (and engine behavior you saw) can have multiple "potential" causes.

FIRST... ALL THESE GS911 faults are both related to TVA (idle Actuator) and in this case I suspect it is only the messenger (symptoms) to something else - I doubt VERY MUCH the TVA is defective. These TVA are quite reliable and it would a fluke that is broke just after your recent maintenance.

These problems are VERY difficult to troubleshoot AT A DISTANCE without seeing the bike and using measurements tools (including GS911, Voltmeter...).

Let me explain further what I think are the 4 potential causes:
(1) While working on recent maintenance, you unplugged the TVA connector (or failed to seat the connector fully in). This would cause fault 5381.

(2) While working on recent maintenance, you remove OR loosen the 3 Torx screw holding the TVA , BUT later failed to seat/tighten the TVA completely flat onto its bracket. This can cause fault 1285 as the EFI system is expecting a direct response increase of TPS (measured in thottle opening degree) if TVA is able to push correctly onto the TB assy when needed (TVA will help maintain correct idle RPM in ALL conditions warm or cold).

(3) IF the free play in the main "pulling" throttle cable is incorrect, when the throttle is closed ,manually or with help of throttle-bodies (TB) springs, the butterflies of TB do not close completely (to normal idle stop). This confuses the EFI system as the TPS (Throttle-Position-sensor at end of TB) is expecting a specific very tight range of values at idle stop. When ignition is turned ON, just before start, the EFI system needs the TPS and TB to be at idle stop range.

(4) The TPS position (rotation) has been upset / moved either on purpose of accidently. Unless both TORX screws holding the TPS were loose (not common) it is very difficult to change the TPS position accidentely. I am including this as the LAST and LEAST possible cause, so we really need to make sure all previous items are correct before we go into this one.


To check item (3) or (4) above, you can use the "TPS check-adjust" routine screens in GS911. Their multi screens procedure is not very friendly (even confusing), AND you need to unscrew the TVA during certain part of the procedure. The reason for all this is the fact the base TPS setting needs to be checked when the TVA (idle actuator) is NOT pushing/holding in Throttle-bodies in fast-idle mode.

ANOTHER METHOD: To check TPS base setting (and if cable are holding TB opened), you can also use the "voltmeter method", but since you have a GS911, it is NOT normally required to use this alternate method. See attached PDF document...
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File Type: pdf BMW_K1200_Throttle-Position-Sensor TPS (version 1-2).pdf (381.6 KB, 496 views)
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K1200RS (2002 IceBlue/Red - 95,000 miles)
-------------------------------------------------
Think twice before you hit [SUBMIT REPLY] - famous quote by another member:
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Last edited by sailor; Feb 19th, 2017 at 11:37 am.
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post #5 of 7 Old Feb 19th, 2017, 2:48 pm Thread Starter
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Thumbs up Re: Cuts out when opening throttle

Yep - as always you guys homed in straight away on the problem. Whilst adjusting the cruise disconnect microswitch, I disconnected the plug highlighted in Gordon's image, and just forgot to reconnect it the last time when I put the bike back together. What a dullard!

It took me 30 minutes to remove the Tupperware and tank, 10 seconds to identify and rectify the problem, and 40 minutes to put it all back together again. I didn't have time to check with the GS911 or go for a test ride, but the engine fired up straight away without any throttle input required, so I reckon it's good now.

Thanks for the excellent response, yet again!

Nick
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post #6 of 7 Old Feb 19th, 2017, 6:11 pm
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Re: Cuts out when opening throttle

Quote:
Originally Posted by nickelliott View Post
Yep - as always you guys homed in straight away on the problem. Whilst adjusting the cruise disconnect microswitch, I disconnected the plug highlighted in Gordon's image, and just forgot to reconnect it the last time when I put the bike back together. What a dullard!

It took me 30 minutes to remove the Tupperware and tank, 10 seconds to identify and rectify the problem, and 40 minutes to put it all back together again. I didn't have time to check with the GS911 or go for a test ride, but the engine fired up straight away without any throttle input required, so I reckon it's good now.

Thanks for the excellent response, yet again!

Nick
Very glad it was that simple, Tupperware excluded

Gordon
Sugar Hill, GA
2001 K1200LTI – Champagne (current ride) Lazy Susan
1998 R1100RT – Never should have sold it
1974 Yamaha TX 750 Twin. Omni Phase Balanced


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post #7 of 7 Old Feb 19th, 2017, 6:20 pm
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Re: Cuts out when opening throttle

Quote:
Originally Posted by nickelliott View Post
Yep - as always you guys homed in straight away on the problem. Whilst adjusting the cruise disconnect microswitch, I disconnected the plug highlighted in Gordon's image, and just forgot to reconnect it the last time when I put the bike back together. What a dullard!

It took me 30 minutes to remove the Tupperware and tank, 10 seconds to identify and rectify the problem, and 40 minutes to put it all back together again. I didn't have time to check with the GS911 or go for a test ride, but the engine fired up straight away without any throttle input required, so I reckon it's good now.

Thanks for the excellent response, yet again!

Nick
Glad it was easy this time around - not all of these strange "my engine cuts out" are easy to troubleshoot at a distance.
AS it is most of the time, 65% of these cases are caused by the last items that were worked on (or in same area).

IMPORTANT: to reset the Motronic-EFI memory, so the engine can "re-learn" adaptations with TVA plugged/installed, I would suggest you remove the Motronic-EFI fuse for 15+ minutes (with ignition OFF of course). Check your manual or CLYMER as the fuse-boxes ave very different in 1999-2004 compare to later models.

This memory reset only need to be done ONCE.
You do NOT need to do the TPS reset dance with 3 throttle opens-closes as long as:
(1) memory is cleared (fuse removal for 15+ minutes OR battery Negative removed for same time)
(2) you make sure throttle hand-grip is fully close at idle stop before you turn ignition ON for 1st engine start (next ride after you put fuse back)
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John (Montreal, CANADA)
K1200RS (2002 IceBlue/Red - 95,000 miles)
-------------------------------------------------
Think twice before you hit [SUBMIT REPLY] - famous quote by another member:
"The value of this board is not founded on dismissing the ideas of others, but by posting to share our experiences and what we've learned from them."
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