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Discussion Starter · #1 ·
Hi,
I have a 2001 K12RS.
When I close the throttle slightly and the revs drop, the power cuts abruptly at 5000rpm. If I continue to decellerate the power comes back on at about 4700rpm. If I open the throttle the power cuts back in sharply at 5000rpm. It feels like the fuel is completely cut off.
It does eactly the same in every gear at exactly the same revs, irrespective of the throttle setting.

As you can imagine, this is a bit unsettling when adjusting the power in a corner in second gear - its like slamming the throttle shut.

The dealer doesnt know what the fault is. He replaced the lambda sensor (which was out of spec) but it made no difference. I have a feeling I'm going to be throwing money at him while he guesses which expensive part needs replacing.

Has anyone had the same problem?
Does anyone know why?

Thanks
Matt
 

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ecu

matthassock said:
Hi,
I have a 2001 K12RS.
When I close the throttle slightly and the revs drop, the power cuts abruptly at 5000rpm. If I continue to decellerate the power comes back on at about 4700rpm. If I open the throttle the power cuts back in sharply at 5000rpm. It feels like the fuel is completely cut off.
It does eactly the same in every gear at exactly the same revs, irrespective of the throttle setting.

As you can imagine, this is a bit unsettling when adjusting the power in a corner in second gear - its like slamming the throttle shut.

The dealer doesnt know what the fault is. He replaced the lambda sensor (which was out of spec) but it made no difference. I have a feeling I'm going to be throwing money at him while he guesses which expensive part needs replacing.

Has anyone had the same problem?
Does anyone know why?

Thanks
Matt
Matt:
It is a known problem. My 02 does it very repeatably. An informal poll at last May's RR Rally showed that it happens on RS and LT bikes. It will definitely cause you to soil your shorts under the right circumstances.

One person on this forum (cabnfvr) replaced the ecu on his 02 and it fixed the problem but that is an expensive proposition.

The 03/04 guys got ecu upgrades to fix other problems so I'm not sure if they ever saw the problem or if the new ecu fixes it. Us 02 guys are just so lucky!

Why does it do it? I believe it is a problem with the engine map in the ecu. For whatever reason at 5k rpm rolling off the throttle to nearly-closed the ecu cuts too much fuel out (or maybe all fuel) and the engine effectively dies. Once the rpm's drop a bit below 5k rpm the ecu gets to a point in the engine map where it is told to increase fuel. Just a theory, but else why do replaced ecu's fix the problem, as opposed to replacing O2 sensors, tps sensors, yada yada.

Mark
 

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Why the sudden fuel cutoff upon deceleration

Matt, the reason the sudden cutoff occurrs is related to a limitation of the linear range of the fuel injectors and the emissions legal engine calibration strategy of your model. In other words the fuel injectors cannot deliver repeatable flow below a minimum pulsewidth that would be required to continue delivering fuel under near closed throttle when manifold pressures drop and mass flow entering the cylinder is below the minimum fuel delivery threshold. The problem can be reduced with a reprogrammed performance chip from rhinewest and others. There is little your dealer can do with oem parts to resolve decel cutoff except verify all adjustments of the throttle slack and tps or to trade it for a newer model.

Hope this helps, Turbo
 

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turbocohen said:
The problem can be reduced with a reprogrammed performance chip from rhinewest and others.
San Jose BMW has been installing Power Commanders on our bikes for a few years now and I'm wondering if anyone out there has been able to correct similar problems that you and I are having with one of them?
I've been chasing down the same problem on my 98 KRS and so far I've replaced the O2 & Air sensors that have helped out alot but the problem is still there when I closed down the throttle slightly, usually while I'm going downhill in the Mt's setting up for a turn.
I'm not sure what else I can do at this point other than go with a P.C. and put it on a Dyno and make a new map for it.
The price for a new chip or a P.C. are about the same but I'd still have to pay the for the Dyno time if I choose to make a custom map.
 

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matthassock said:
Has anyone had the same problem?
Matt, check out this thread from the old board. Sometimes the TPS (Throttle Position Sensor) needs to be adjusted, as "turbocohen" has stated above. Specifically, Message No. 63527 in the thread. HTH
 

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turbocohen said:
Matt, the reason the sudden cutoff occurrs is related to a limitation of the linear range of the fuel injectors and the emissions legal engine calibration strategy of your model. In other words the fuel injectors cannot deliver repeatable flow below a minimum pulsewidth that would be required to continue delivering fuel under near closed throttle when manifold pressures drop and mass flow entering the cylinder is below the minimum fuel delivery threshold. The problem can be reduced with a reprogrammed performance chip from rhinewest and others. There is little your dealer can do with oem parts to resolve decel cutoff except verify all adjustments of the throttle slack and tps or to trade it for a newer model.

Hope this helps, Turbo
Turbo:
If that is the case, why does it not happen at all at 6k rpm or 4k rpm, only at 5k rpm? If it were an injector open-time resolution problem it would always happen, certainly at rpms just above and just below the magic 5k. Also, since the pulse width is a minimum at idle and the bikes idle fine, I would assume any pulse width greater than that should be achieveable and certainly such a pulse width at 5k would keep the engine running when the throttle is suddenly closed.
Mark
 

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Discussion Starter · #7 ·
Thanks for the good advice. The bike goes in for its 36000 in a couple of weeks.
I'll let you know what transpires
Cheers
Matt
 

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Discussion Starter · #8 ·
Problem Fixed!

Hi
I said I'd come back when the bike had been serviced.
The bike came back from the shop yesterday. They had replaced the TPS and the throttle cables during the service. The problem was exactly the same.

They took it back and kept it for a week (I think they may have had a guy from BMW UK look at it). They finally replaced the ECU which fixed the problem. BMW would not do a warranty replacement so the unit cost around £550 (uk pounds). The shop cut me a good deal on the labour charge though so it wasn't as bad as it could have been.

I gotta say - the bike goes GREAT now. It had been bad for so long I had forgotten how good it used to be. I can use the whole rev range now and it's like a rocketship. So I'm glad I got it done. I don't want a K1200GT so bad now.

Cheers

Matt
 

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new ecu

Matt:

I'm glad your bike is running the way it should. It must be awesome.

I have to say that it is unfortunate that BMW is profiting from a defective ECU installed on pre-03 bikes. I don't understand rewarding their incompetence by purchasing a new ECU for $958, or for that matter, for any amount.


Mark
 

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Why does my '97 go like a train and not seem to suffer any of these problems? Am I just lucky or perhaps I don't give it enough stick?

The only problem I've encountered was after a long high speed sustained cruise, then slow urban ride, the idle rpm was running a bit higher and slightly erratic. Didn't come back when the bike was parked up and run again. Since the 150mile cruise went like a dream, I didn't worry much about the last few miles.



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voxmagna said:
Why does my '97 go like a train and not seem to suffer any of these problems? Am I just lucky or perhaps I don't give it enough stick? .
Your just lucky. This problem is not just in our heads, it's a real f#$k up by BMW and could easily cause a fatal accident in a turn at speed if you didn't know about it and do the right thing to overcome it when it happens.
 

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Discussion Starter · #12 ·
I agree with jerry, this could be a really dangerous fault - its at its worst when getting it on in a second gear corner at about 80mph. When the power cuts off, the engine braking comes on hard and then the power kicks back in when the revs drop to 4700. It was after nearly being pitched into the armco (with the missus on the back) that I decided I either had to fix it or sell the bike.

And Mark, rewarding BMW is the farthest thing from my mind. If someone from BMW would make themselves available I would readily stuff the old ECU up where the sun doesn't shine....

Audi have just had the grace to admit they have a production problem and refund the £879 I paid for a replacement TT dashpod. I think BMW should do the same - its clear from this forum that I am not alone with this problem.

Ok I feel better now. Thanks for listening.
 

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Decellerating Update

After trying to solve this same problem as Matthassock had by replacing various sensors with limited help, I decided to search for a Motronic to replace my orginal one. Fortunately one of the vendors here, www.beemerboneyard.com had one that he picked up from a dealer that went out of business and was selling it for a fraction of the BMW price.
I installed it yesterday and took the bike out for a ride today up into the Mt's, 4,000 ft from sea level. The bike now has no injection problems like it did before and it's as smooth as the rest of the KRS's without this problem.
The bummer of this story is, that I have the dreaded clutch slave fluid leak and have to go through that whole hassel of splitting the tranny from the motor as others have to correct it. I'm not looking forward to this one but I'm glad that the other problem is solved.
 

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I've been reading this tread and think that BMW should not be allowed to get away with this crap. Honestly, I think we are the only ones that can fix it. For instance, there is an active California based law suit against Volvo for a faulty throttle body on their S70 class vehicle that after several years has finally come to a settlement. They are now required to extend their warranty to ten years or 100k miles on this component to all owners. The issue was very similar to this whereas, the idle would just start fluctuating at times. The cost of the repair was $1500.00. This issue with the ECU is very simular to that. I believe we have enough collect evidence, strength and resources to get BMW to succumb to what is just. And that is pay for these damn repair cost. For crying out loud, they have virtually admitted there is a problem. It wouldn't be difficult to get a law office (maybe the same one that persuaded Volvo to do the right thing) to take on a suit.

The question is are you willing to commit to going forward. I'm willing to fight, but I can't do it myself.

Standing by........

Jeff

Blk 02' RS
 

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BMWorDuc said:
After trying to solve this same problem as Matthassock had by replacing various sensors with limited help, I decided to search for a Motronic to replace my orginal one. Fortunately one of the vendors here, www.beemerboneyard.com had one that he picked up from a dealer that went out of business and was selling it for a fraction of the BMW price.
I installed it yesterday and took the bike out for a ride today up into the Mt's, 4,000 ft from sea level. The bike now has no injection problems like it did before and it's as smooth as the rest of the KRS's without this problem.
The bummer of this story is, that I have the dreaded clutch slave fluid leak and have to go through that whole hassel of splitting the tranny from the motor as others have to correct it. I'm not looking forward to this one but I'm glad that the other problem is solved.
The problem it seems with the Motronic is nobody really knows what ECU firmware version they are riding on. If as I suspect, aftermarket chips don't have this problem, then firmware versions, not sensors is the first thing I'd look at. I wouldn't be surprised if the Moditec diagnostics reads the ECU firmware version. After all, it can't diagnose to a table it doesn't know about.

So, the next time they plug in their Moditec, Ask for the ECU firmware version and post it here. It will probably be dated.

Those that have the same problem, post your ECU firmware versions as well. Then when anybody considers buying a bike used, they can request the ECU firmware version and know before buying if they are going to get a problem without riding the bike. If dealers can't sell bikes used or otherwise to wise buyers with dodgy ECU firmware causing this problem, they'll have to do something about it. Suddenly a rash of K12 'working' ECU's will then appear cheap on Ebay!

If I'm wrong about Moditec reading out the firmware version, the company I read here or on the other board that rebuilds broken ECU's would almost certainly know how to read the embedded code to re-programme new chips where they have failed. They may even already have a few sets of firmware versions sitting on their hard drive.

It needs the riding community to try and identify the ECU firmware variations first. That is going to be the main thing which determines your oem ride characteristics and allows you to compare apples with apples, not do it just on year models alone. If this problem is responsible for causing accidents on this model and there is a link to the ECU firmware version possibly causing it, I wouldn't like to be the manufacturer with a service network letting the dodgy units just pass through.

In the past we've seen recalls for vehicle mechanical parts we understand, like braking systems, steering parts, wheels, tires, etc. But to be honest, the firmware code in your ABS and ECU systems is just as likely to be responsible for causing loss of control or an accident. In cases such as this, a rider cannot be expected to have the knowledge of a complex engine management system - so this responsibility fits squarely on the manufacturer to get it right and safe.

BMWorDuc, it's probably a bit late now, but it would have been useful to know if all the ECU label codes on the good and bad one were the same. If I had a spare ECU, I'd love to see if the embedded firmware code in their chipset is accessible. Motronics 2.4 is pretty old in chip terms and shouldn't be too fancy.



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voxmagna said:
BMWorDuc, it's probably a bit late now, but it would have been useful to know if all the ECU label codes on the good and bad one were the same. If I had a spare ECU, I'd love to see if the embedded firmware code in their chipset is accessible. Motronics 2.4 is pretty old in chip terms and shouldn't be too fancy.
http://us.st11.yimg.com/store1.yimg.com/I/yhst-15102260216258_1886_5946028

Orginal Motronic:98 KRS
BOSCH 980515 26SA5035

1 261 204 314 (810) 86515 17A 0429

1 465 232
...................................................................

Replacement Motronic:
BOSCH 030505 1039S01774

0 261 204 314 (810) 38505 1763 0676

7 673 166

Here's a site that sells a new chip for our bikes and has listed the Motronic #'s which allow you to find out what generation of Motoronic you have, http://www.rhinewestperformance.com/K1200RS.htm

It appears that my orginal one was the third generation Motoronic and the Replacement one is the fifth & last generation Motoronic.

I'd be willing to join in on a class action suit against BMW and use my old Motronic as evidence, if someone wants to pursue this.
 

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BMWorDuc, That's useful. Talking 'generations' can be a bit nebulus so other owners with a similar problem need to post their ECU label information to correctly identify a pattern of problems.

I'd still like to know from anybody putting their bike in soon for a Moditec, if the ECU firmware version can be read out and has any relevance to the label codes. Remember bikes may have had ECU's swapped out and it's easier (particularly if buying a bike) to get a Diagnostics readout. I'd insist on this anyway on a bike or cage I might buy in future. If this can be done without removing plastic you can pay the 1/2 hour charge for diags and choose to walk away from the deal if you want.

The more you know before buying, the harder it becomes for a dealer to fob you off. A pattern of ECU labels/Firware versions with good/bad rider feedback on this problem builds a strong case which dealers can't ignore. I doubt they would wash their hands of older bike sales either, as it's their livelihood. Let the dealers beat the path to BMW's door, they have more to lose.

I knew about the Rhinewest firm, but it was a recent post here or elsewhere referring to a firm repairing oem ECUs that intrigued me most. The bike you buy and its characteristics are down to the ECU firmware, that's the same with any 'fly by wire' electronically managed system.

For now I think you are saying the early ECU gave the problem but the one you think is much later does not, correct?



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NHTSA-Throttle Response

I have an 02 RS and have not been happy with the throttle response coming off idle at high rpm. It may be related to the same ecu related problem. At high rpms, 7000 or so, the throttle acts almost like an on off switch, with the power coming on abruptly. This makes it next to impossible to apply smooth linear power while exiting out of a corner.
This has forced me to come out of the corner in one gear higher than optimum, to keep the rear end from breaking loose.

I had thought that this problem might be issolated to my bike, but now I suspect it might be more widespread.

A few years ago, I and many other Harley riders had a problem with the ignition suddenly cutting out while under way on our FLHTs. We felt that this was a safety issue. Harley would not voluntarilly replace the ignition switch which was causing the problem. After replacing two igniton switches, I had had enough. I found other riders on the internet, and we each bonded together and wrote to the NHTSA. They in turn asked for more information and my old ignition switch. Within a relatively short time the NHTSA forced Harley to do a recall on all the effected switches. They also reimbursed me for the two previously replaced switches, and installed a new upgraded unit.

If the ecu problem is sufficiently widespread, I have no doubt that the NHTSA will step in and force BMW to fix the problem at no cost to the affected owners. Incidently, almost of the bikes were out of warranty.
 

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voxmagna said:
For now I think you are saying the early ECU gave the problem but the one you think is much later does not, correct?
From what I've read about this, I'd have to say YES. The older ones seem to have the problem whereas the newer generations of the Motoronic seem to be OK, but I don't know that as a fact. There may be others out there with newer bikes that have the same problem.

One of the problems with this whole deal is that my dealer told me when I first took my bike to him to get it check with their diagnostic set up, is that they can only check the sensors and they CAN NOT check to see if the Motoronic itself is faulty. The only way they can truly see if it's bad is to change it out with a different one.

RSrider-
Your ECU problem sounds like the same one I had.
 

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Yes they may be right up to a point. But what we're trying to find out is when they connect the Moditec, is there a header telling them the ECU serial number, build date etc. like on the label. 'cos if I had a bike with or without problems, rather than take off plastic and search out the ECU label, I'd rather get it clean off their diags.

There's 2 strands to this. 1. The dealerships can't ignore a connection between an ECU safety fault and your bike or one they sell if the ECU build data is shown in the diagnostics, and 2. anybody looking at buying has an easy job to check up. If anybody refers this to the safety administration, I guess BMW would have to come clean on the ECU Firmware variations, what bikes had them, what the the changes were and for what reason. In those sort of investigations, commercial confidentiality doesn't usually hold much water for witholding information - no hiding place. Who knows whether riders may already have been injured or killed. Apart from the usual checks on a bike post accident, whose going to check the ECU? It'll just be put down to wet road, rider error etc.

Until then, the more information gathered from the community on their particular ECU version, bike year etc, the better it may be to see a pattern. Just because something changes and is newer doesn't mean a problem is eliminated, often it brings new one's!

Maybe we need a form here to post basic bike details, how to get to the ECU label, the info it carries, and whether the rider has suffered this problem or anything similar. I'm nervous that we say how to check the problem, unless a real safe way can be found. We want to keep our community members riding!

I'm probably not the sort of rider that pushes the rpm the way others do, If I have this problem I'd sure like some more certainty on what's controlling my life, when I think I'm in control.



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