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Message |
    
Xb9sbear
| | Posted on Thursday, August 14, 2008 - 01:41 am: | 
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Just had my ecm fry for the second time. The first time it took the coil with it. This time the coil is ok, but will probably still replace. The first time I rode it about 3 miles to a gas station b4 she completely gave up the ghost. That's what blew the coil. This time (a little smarter) I pulled her off the road immediately.
Same symptoms. She suddenly overheats and drops a cylinder. Almost no power.
I don't want to make another temp fix. Hoping someone out there recognizes this issue. Since the first issue, I switched to the Jardine Titanium Exhaust but have been holding out on opening the airbox until I got a race ecm. So, I may upgrade this time 'round, but there's that nagging suspicion that this may be a symptom of a larger problem and that it may come back and bite me again.
Maybe a short of some sort? Causing the ecm to overheat and fry, taking the coil with it? The coil runs hot when you fire her up. They told me last time that I cracked the coil.
Anyone got any ideas?
I should mention she's an '03XB9S Lightning with close to 50k in miles. There was a short issue way back 'round 20k that took a couple attempts to fix. Will have to look up the receipts to remember just what the issue was, but I know it had something to do with the ignition.
Robtk! a.k.a. "Special K" |
Court
| | Posted on Thursday, August 14, 2008 - 06:56 am: |
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Your dealer should be able to fix this pronto. |
Reepicheep
| | Posted on Thursday, August 14, 2008 - 10:06 am: |
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Hopefully they check the voltage regulator (IMHO). |
Xb9sbear
| | Posted on Thursday, August 14, 2008 - 12:55 pm: |
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Just like pretty much everyone else in the Buell world, my dealer is the last place I wanna take this bike. So, I've taken it to this new place where they just hired a Former Buell Race Mechanic. He and I are pretty much on the same page so far.
Previous issues turned out to be a faulty Temp Sensor that took a couple tries to fix b/c of chafed wires that had to be replaced first and also a loose stator that was shorting out but HD thought it was a leaky oil line that was spittin' on some contacts. Both of those probs seemed to be fixed. Suspect some sort of short in the wiring harness but will check on the voltage regulator as well.
Robtk! a.k.a. "Special K" |
Id073897
| | Posted on Thursday, August 14, 2008 - 02:41 pm: |
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This all seems a bit dubious to me. To fry a coil, you usually need to ground the primary wire, so that after charging the coil only the ohmic resistance will limit the current.
To fry the ECM, just the opposite would be required - if ever this would reason enough for a failure. Usually the chips are adapted to this and the ECM is (somehow) monitoring coil current.
It's imaginable that a faulty chip inside the ECM would make this possible, but not twice in sequence.
Regards,
Gunter |
Xb9sbear
| | Posted on Friday, August 15, 2008 - 02:50 pm: |
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It seems that when the ecm went the coil suddenly overheated. Right now, with the bad ecm in the bike the right side of the coil gets incredibly hot just seconds after you fire her up. She's runnin' on just the front cylinder, and there is no spark to the back one. But take out the ecm and swap it with a good one and no prob with the coil. Leave the ecm in and trade out the coil and it overheats too.
The first time, the coil actually cracked from excessive heat caused by me foolishly trying to get her further down the road.
No doubt that the two are possibly and probably related. Its just a question of what caused it then, and what caused it now. So I'm looking for the common denominator. That being a short or maybe the voltage regular?
This is where we stand. So far haven't been able to duplicate a short. Was hoping someone might have other ideas.
Robtk! a.k.a. "Special K" |
Sparky
| | Posted on Friday, August 15, 2008 - 09:41 pm: |
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The only way I can think that a coil can overheat is when a constant +12VDC is applied with full current drawing through the coil regardless of the normal ignition signals from the cam position sensor that should be present.
So I would think that if there were a short-to-ground in the signal wire circuit that goes from the suspect coil to the cam position sensor, the coil would overheat because there is no normal interruption of the abnormal constant current being applied. I would double-check all the wiring involved with the ignition circuit very, verry carefully, looking for chafing spots in places where the wire harness might touch ground potential areas. |
Xb9sbear
| | Posted on Saturday, August 16, 2008 - 04:21 pm: |
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Hey Sparky!
Now that sounded like you know what your talkin' about! LOL
I'm forwarding that to my mechanic as we speak.
Thank you very much...
Robtk! a.k.a. "Special K" |
Id073897
| | Posted on Saturday, August 16, 2008 - 04:58 pm: |
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The CPS is not connected to the coil but to the ECM, as is the coil's signal wire.
Your description of the errors in various combinations clearly shows that the ECM is the culprit, as it doesn't terminate the signal wire correctly (after maximum dwell). I have no idea how this can happen, but obviously the chip controlling the coil primary is broken (or something around this chip), providing full ground connection and therefore destroying the coil. Perhaps it's a good idea to check all ground wires connected to the ECM to exclude some weird side effects - even if this might be no more than a shot in the dark.
System Ground is pin 1 / black plug
Coil Ground is pin 11 / black plug
Sensor Ground is pin 7 / gray plug
The pin number is printed at the back side of the plug.
Regards,
Gunter |
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Fried ECM and coil