SteveST1300
Vendor
I hope that was it Jeff good luck.
Ignition Problem?
- Thread starter wjbertrand
- Start date
Wow, lets hope you have found the problem.
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wjbertrand
Ventura Highway
It's not the fuel pump. I would have been very happy to be wrong. The symptoms made no sense but I replaced it as a means to eliminate it and several folks have suggested it might be the issue. It's also the only issue that has lead to the bucking and misfiring I am experiencing that's described, though not exactly, in other posts on various forums. On to the FPR then, which also doesn't make a lot of sense to me either, but since I have a perfectly good one on the bench...
hey Jeff, sorry to hear this is still unresolved. I lost track over the dozens of posts, have you scrutinized the fuse block for a flaky connection or even an intermittent fuse? perhaps the 4250 RPM creates a buzzing that opens some small mechanical failure in the electrics.
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wjbertrand
Ventura Highway
Thanks Doug for the continued support. I did pull and examine the fuses that seemed relevant. Trying to remember, I think they were labeled EFI and Ignition? They looked fine and the connections were clean. I put them back in the other way 'round, just to force a new contact but alas, like everything else I've tried, it made no difference. I did have a car once where the fuse link inside actually fractured. No visible burning at all, I had to hold it up to the light just right to see the crack. In this case it tested open with my meter though. I do agree that there may be a sympathetic vibration related issue. That's one reason I swapped out the fuel cut relay. There's half a dozen identical ones used all over the bike. The only other reason I could think that there's such a specific RPM would be ECM related, but of course we've eliminated that early on a while back.
BTW, I looked up NGK plug caps based on your comment in the post about re-building them, but they don't have a part for the ST1300.
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My bike has developed a similar hic-up. Last year once or twice the bike just shut-off and restarted while cruising the highway. Maybe happened two or three times the whole summer.
Now.. it happened a couple of times this month, three times this morning on the way to work. I would say mine is just over the 4250 rpm, but just as I was thinking that it happened when I was clearly over the 4500 rpm line. So it was probably at that particular rpm just because I spend most of my time cruising there in the morning with little traffic.
Maybe it's similar to yours, maybe not... but I don't seem to have any other symptoms of bucking or mis-firing. Just bike engine is off, then on and my cheeks are a little tighter.
Now.. it happened a couple of times this month, three times this morning on the way to work. I would say mine is just over the 4250 rpm, but just as I was thinking that it happened when I was clearly over the 4500 rpm line. So it was probably at that particular rpm just because I spend most of my time cruising there in the morning with little traffic.
Maybe it's similar to yours, maybe not... but I don't seem to have any other symptoms of bucking or mis-firing. Just bike engine is off, then on and my cheeks are a little tighter.
How about swapping like-amperage fuses around between sockets (regardless of function, do as many as you can)? its easy, free, and if it doesn't help there's nothing that needs to be undone. Also, is there anything on the fuse block itself that could be losing contact? The severe bucking still sounds like it could be a power delivery issue
If I was evil I'd suggest a crank shaft bolt loose that hasn't broken yet but I wouldn't do that 
Seriously though why it only happens when the bike is warmed up at a specific and reproducible rpm leave me with no guesses. Blrfls though of a scope and looking at what really changes when it happens makes me wish you had one to sniff around.
Seriously though why it only happens when the bike is warmed up at a specific and reproducible rpm leave me with no guesses. Blrfls though of a scope and looking at what really changes when it happens makes me wish you had one to sniff around.
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wjbertrand
Ventura Highway
This does sound similar. It's like someone is flicking the kill switch on and off quickly. My bike does not completely quit running though. Is that what's happening to you when you say it shut off? You have to hit the starter to get going again? Does your tach needle bounce when this happens?
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wjbertrand
Ventura Highway
That makes two of us - on both counts.
Blrfl
Natural Rider Enhancement
This is why I keep thinking power, and it's reinforced by the the fact that the FI light isn't illuminating. If it were a sensor problem and the ECM was still running, there'd be a complaint about it.
Some of the reading I've done about car ECMs says that watchdog resets, when the software hangs up and the whole ECM has to be reset, are pretty common enough and recovery happens quickly enough (< 10 milliseconds) that drivers don't even notice it happening. If that kind of design carries over to motorcycles, it fits your situation pretty well: power goes, fueling and ignition stops, the engine runs a few revolutions on inertia, power returns, the ECM sees indication that the engine is being turned over and starts fueling it. The difference between a watchdog reset and a power drop is that you lose the engine long enough to be visible.
For what it's worth, you can pick up a headless 'scope that plugs into the USB port on a laptop for under $150. It doesn't have to be a laboratory-precise, high-bandwidth unit, just something that can capture and store a couple of seconds on either side of the event.
--Mark
Yep, just like someone flipped my engine stop switch off and right back on. Don't have to hit the starter as the bike is just pop-started into running again. Never happened when sitting still or going slow, just when I am cruising on the highway. Don't know about the tach, would assume it stays measuring engine RPM, it happens so quick by the time I move the eyeballs the engine is running again at full speed. Not losing full electric power, my dash (fuel gauge, clock, etc..) does not reset and my phone does not beep like it lost and regained power. But the FI light comes on like the bike was just started, after five seconds it goes out. No error codes.
This sounds like an interesting theory because it would also explain the lack of error codes (can't throw a code while the software is being reset) but I think Jeff swapped ECM units with Hal's bike and the problem stayed with Jeff's bike.
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wjbertrand
Ventura Highway
OK, that's a key difference, my check engine light never comes on when this happens. It will come on like you describe when I purposefully turn it off and on as quickly as possible using the kill switch though. In your case I would suspect a dirty connection in the kill switch housing.
Tip over sensor?
there's your solution Jeff. To test it out you should tip the bike over, hard, and then call the insurance company.
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wjbertrand
Ventura Highway
So Mark are you saying there's a loss of 12V power only to the ECU somehow? There certainly does not seem to be a global loss of power. I've watched my Datel meter during the misfire event and it's rock steady. Also no clock resetting events, or if riding at night, dimming of the head or dash lights.
This is true, not only did the problem stay with my bike, Hal's bike ran perfectly with my ECM installed. I rode them both back to back. I think what Mark is saying is that something external is interrupting power to the ECM or causing it to hang and re-set??? If that's the case it wouldn't matter which ECM was installed. The head spins trying to think what would cause that!
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wjbertrand
Ventura Highway
Thought about that, but once triggered the TOS requires a key off cycle to reset. Had one go bad on my ST1100 and I learned to cycle the ignition key whilst underway. Made for some pretty healthy backfires too!
That's right. REALLY want to fix this for you.
What Mark was describing is a watchdog timer expiring, causing the ECM to reset the s/w execution. Its common in real-time s/w applications to have a hardware timer that needs to be reset periodically by the s/w. The reason is if the s/w somehow hangs up for an unexpected reason, since it can't reset the hardware timer the timer will expire and the s/w will get reset as a result. This prevents the s/w from just stopping altogether if it somehow misbehaves.
If you have some kind of internal ECM s/w problem, then it would seem likely that it would have followed your ECM to Hal's bike, which didn't happen. And by removing the ECM entirely you have probably removed all power from the unit, so if it has somehow stored some weird setting or sensor value internally that hopefully would get cleared by removing the power (unless it has a keep-alive battery internally).
One other possibility is that the ECM is sensing something weird on your bike, which then causes the s/w glitch regardless of which ECM you have installed (yours or Hal's). Like you say, diagnosing that kind of failure mode isn't going to be easy.