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Norge stalling at low idle

Discussion in 'BNS12 Chat & Tech' started by Zipster, Aug 1, 2009.

  1. RJVB

    RJVB GT Reference

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    No ethanol mention doesn't mean there's none :S I don't know where you live, but I think 5% is common throughout Europe, 10% is becoming the norm here in France ... and apparently 15% in the US. Most marques have only tested up to 5%.

    Ethanol has less energy than gasoline. I'm not exactly sure how this works out, but I suspect that bumping up the ethanol percentage gives a leaner mixture, unless the ECU somehow has a way of compensating (just injecting more would work, or?)
     
  2. Herb

    Herb Just got it firing!

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    Point taken re: ethanol. I am in the US, Georgia to be specific, and ethanol has been creeping into the fuel here. Also I travel a good bit, in fact the trouble started on a road trip.

    Wouldn't the Lambda probe give the ECU the info it needed to detect a too lean condition?

    I tried both enrichening and leaning the idle mixture using the VDST, but could not detect any change either way. I dont have a CO analyzer, so don't know if the mixture was actually changed by the VDST; but suspect that the Lambda would have overruled any change regardless.

    The injectors passed the VDST test. Could a partially clogged fuel filter be playing a part in this? I don't note any maintenance schedule for replacing it; but I know from previous BMW experience that they can clog in as few as 25k miles. Of course, seems like that would manifest itself first at larger throttle openings and this bike runs very well,only exhibiting problems on closed throttle including the popping and banging in the exhaust that so many others have complained about.


    Going back to your earlier question about the speed of the stall....... If I close the throttle and squeeze the clutch, RPMs fall rapidly and apparently the ECU fails to halt the fall ( or responds too slowly?) when they reach 1100. Only at about 800-900 rpm do I feel it try to recover, usually unsuccessfully.

    Could one of the other sensors; ie: ambient air temp, intake air temp, oil temp;
    be supplying faulty data? They tested ok on the VDST, both hot and cold.
     
  3. RJVB

    RJVB GT Reference

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    This is getting beyond my level of expertise ;)

    The engine temp sensor is known to be installed clumsily, resulting in an under-estimated temperature reading. But that would cause a richer mixture, so it should not be the culprit here.

    Do you have an aftermarket muffler? I have noticed indeed that since I installed my Agostini, I must be a bit more careful closing the throttle rapidly with the clutch in (and I like to freewheel... ;) ). Often, when doing that, the engine feels like it will or might stall, just the way you describe.

    Others who bypassed the stepper motor reported a quicker return to idle after releasing the throttle. Did you also? You may indeed want to put it back into the loop, possibly with a valve on the intake as I forget who here also did.
     
  4. Herb

    Herb Just got it firing!

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    It's clearly past my level as well.

    Yes, I put a Mistral on it about 17K ago; but the stalling has only started recently.

    I am going to ask the dealer to supply me with a new stepper under warranty and see what effect that has. As it is now, the bike is unrideable if I am going to be in slow traffic. I must have pushed the starter button a hundred times during a slow crawl through downtown Atlanta this past weekend. That can't have been good for the starter or motor. And stalling in traffic is dangerous!!!

    What about Todd's ECU swap and PC-V ? Might that be a good way to go on this?


    Herb
     
  5. GrahamNZ

    GrahamNZ High Miler

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    Zipster

    My reason for asking is that there are only two ways I know of to vary the idling speed manually. One is to adjust the throttle opening cable so that the throttle is always slightly open - in which case the idle speed will increase at full lock. The other way is to move the throttle stop screw (known here as "the sacred screw") on the left throttle body. That is a No! No! so it's important to determine if that's what was done. If it is, then all is not lost, as I posted about a while back. Call out if you need more help with that.
     
  6. Zipster

    Zipster Tuned and Synch'ed

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    Graham-
    Talked with the mech today. He did not touch the sacred screw, in fact he commented on the sacredness of it. He did slightly back out the mixture screws on the throttle bodies just to keep some more fuel flowing. Not the best solution, so I'm going to restore them to their previous setting and he's ordering a new throttle position sensor for me. I'll tolerate the stalling from the out of control TPS (until we can replace it) rather than run an overly rich mixture all the time.
    At this point, they're not willing to swap out the stepper motor until they see if the new TPS cures it. Good news it won't take long to tell since this bad girl will stall out in no time if they're wrong.
    I'll let you all know how it goes, I appreciate the suggestions.
    Rob
     
  7. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Zipster wrote:
    Sorry to say but by backing out the air bypass screws he has leaned out the mixture. Both bypass screws should be closed, or one just slightly open to have a sync at idle. Idle speed is to be controlled by the stepper motor. At lease he hasn't messed with the "sacred screw." Do you have the latest map installed on your Norge (see https://www.guzzitech.com/index.php?op ... 0&id=16501). The latest maps set the new desired idle at about 1200 RPM.
     
  8. Zipster

    Zipster Tuned and Synch'ed

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    John-
    Yes, Moto Nexus installed the latest map before they started the troubleshooting on my stalling problem. Interesting that he leaned the mixture as I seemed to lack power and the fuel consumption nearly doubled (worse!) on the 100 mile trip home. What's your opinion of the likely root cause of stalling at low idle? He sees wild voltage fluctuations on the TPS so he thinks it is bad and that the stepper motor is probably OK.
    Thanks-
    Rob
     
  9. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Rob,

    If he is seeing the TPS vary that much, I'd correct that issue first. If the problem persists then it is time for a close look at the stepper motor operation.

    By having the bypass screws open too much it may be impacting the lambda causing the drop in power an efficiency. These new bikes are particular to how they are set up. If everything isn't just right, performance and mileage suffers.
     
  10. Zipster

    Zipster Tuned and Synch'ed

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    Update...

    Picked up the Norge today after finally getting the TPS replaced under warranty. Mech also redialed TBs and test rode for 15 miles, ran great with no stalling or "SERVICE" warnings. I headed out and got 15 miles from the shop when it stalled again the first time I had to stop at an intersection. Unfortunately, my other lift home is gone and the shop is closed so I've got to take her home (100 miles). Every time I let it idle it would stall and give the SERVICE light. Then restart, and it ran sluggishly or stalled again. Finally restarts and runs. Runs fine at higher RPMs and mpg is back up to 46+. Got her into the driveway at home, stalled again and could safely check the diagnostics: got the ECU error code 11.
    Although I do believe the TPS was bad as it runs better now than before the replacement, I think the stepper is bad and "choking" the engine when the RPMs are allowed to drop after it is warmed up. Does that make sense?
    What is ECU error code 11?
    Warranty expires in 28 days so I need to figure this out. I haven't got the time to keep running her 100 miles each way to the dealer. If I'm confident it's just the stepper, I'll wait for Todd's cutoff kit. Maybe isolate it temporarily.
    Rob
     
  11. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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  12. Zipster

    Zipster Tuned and Synch'ed

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    Another note...checked the valves tonight and they're spot on. ECU fault code 11 is a throttle ground. Modular connection for the TPS, so the mech didn't wire it wrong.
    ??
     
  13. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Zipster wrote:
    Can't wire it wrong, It's a plug in deal. Only the factory that makes the wire harness can get it wrong, which is doubtful.
     
  14. RJVB

    RJVB GT Reference

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    A well-conceived plug will not allow wrong connections, but it opens the door to all sorts of other connection problems that are hard to trace! Someone might have unseated it by pulling on the cable instead of on the plug, for instance...
     
  15. Zipster

    Zipster Tuned and Synch'ed

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    Still struggling with this issue and just don't have time to run it 100 miles to the dealer. I've taken the TPS connector off, checked the connector for bent pins or closed channels, sprayed it and cable end with contact cleaner, reseated the plug very firmly, removed the charcoal canister, checked the valves, and it is still stalling out once it gets warm. When it stalls, it doesn't want to restart for a minute or two and it won't take any throttle. Some of the times it stalls, it leaves an ECU error code 11 which is a throttle valve ground fault. Wondering if it is that the bike is warm or that riding for awhile is causing a ground to pop loose? Where is the ground for the TPS? Not sure what to try next. May have to get over to MotoNexus next Saturday but they're not really sure what to do either. Bad ECU?
     
  16. GTM®

    GTM® Administrator Staff Member GT di Razza Pura

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    Sure sounds like a faulty TPS. I'll be curious to hear how it's replaced, as it's buried in the throttle body, and not bolted on like the old style. Keep us posted.
     
  17. Zipster

    Zipster Tuned and Synch'ed

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    The TPS was just replaced last week with a brand new one and didn't help the problem. Mech said it was a pain to get off since the mounting screws are close to the frame.
     
  18. crswa

    crswa Tuned and Synch'ed

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    I think my Breva 1100 is having a milder form of this same problem. Engine slows and stumbles and sometimes stalls when closing the throttle with the clutch in. I've taken to keeping just a bit of throttle on while I pull the clutch lever and then close it completely after a couple of seconds. That seems to help, but it's just a band aid. I'm very interested to find out what the final resolution to your problem is. I haven't bothered to pull out the emissions canister yet because I didn't think it was worth the trouble. After reading this thread, I'm going to yank that sucker this weekend and see if it helps.

    Also, don't worry about your warranty running out. If you identify a problem during the warranty period, they have to keep working on it until it's fixed even if the warranty expires before they finish. It's the law.
     
  19. Zipster

    Zipster Tuned and Synch'ed

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    Does anyone suggest valve clearances other than those in the service manual? I set mine at 0.10/0.15mm.

    I will also be taking her back to Moto Nexus next week to reset TPS again. After cleaning and reseating the TPS cable connection several times, I'm no longer getting the ECU error 11 (TPS ground fault). Unfortunately, the bike still doesn't want to start cold and idle unless I hold in throttle. Good news is that it doesn't stall once warmed up, at least for now.
     
  20. Zipster

    Zipster Tuned and Synch'ed

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    Got her back from Moto Nexus today. Steve had her for 2 weeks and looks like we got the problems resolved. This was a pretty complex troubleshooting situation.
    1. He found a fried wire in the wiring harness lead from the alternator. Wasn't charging properly and was shorting out. Apparently this was causing the ground faults with the TPS. There may not have actually been a problem with the TPS itself, just may have been getting some voltage through the ground due to the short that screwed up the TPS output.
    2. He also found water in the gas tank. The vent valve was stuck open and letting water vapor in. Fuel filter was nasty so he pulled it and replaced it with the all-metal variety. Unfortunately, I didn't get to see it to check the condition of the plastic half.
    She runs great now and all appears to be well. I haven't had a chance to talk directly with Steve yet but plan to do so to get the full detail on the tank vent and the wiring. Rob
     

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