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Discussion Starter #1
Okay, sitting comfortably with a beer and ready for a short read? Here goes...
last year my 2010 990smt cut out on me. Did this randomly until I realised that the fault code was in fact flashing up cylinder 2 coil circuit error. This is 3 long and 8 short flashes. The bike would often restart after turning it off and on again. It would then randomly cut out on my, outside lane of the A13 was one partucularly memorable one as I cut 3 cars up getting over to the hard shoulder. Right so here are the facts so far. Got a new coil and (assuming the rear was cylinder 2) put a new one in the front (yep|) and moved that to the rear. Problem persisted, random cutting out. No pattern, it would run for days and cut out would sometimes be just after starting or riding for an hour....absolutely no regular pattern. Now I got new plugs, known good coils (checked for spark etc) and problem still existed. Got it plugged in, faults reset, ran once....boom. Problem back but now a hard fault, it won't run and only fires on rear cylinder. Got a friend to come over, plug in, checked TPS, cleared faults...now it still has no spark on the front cylinder, which is cylinder 2. This weekend did the coil/plug check by turning it over and rear cylinder sparks with either coil/plug combo. Then did a continuity test from the ECU to the plug....both good. Checked the loom plug on the side of the tank and all clean with no corrosion. So this is where I am so far.
1. wiring from ECU to plugs good
2. known good working stick coils and plugs in both cylinders
3. hard fault saying cylinder 2 coil circuit error
4. not fuel related, this is definitely spark related and a hard fault now on cylinder two, the front one.
5. The fault exists either at ECU level or circuit leading to it.
6. Someone else had the same fault and spent 3 months in a garage with them replacing loads of parts (fuel pump etc).

Soooooo.......moving on from here to try and get my 990 running I need to know the following and hopefully someone can maybe have had the same/similar and solved it.
1. is the spark pickup operated by one point or two, i.e. does this bike have a wasted spark in that it will fire both plugs (one at compression and the other between exhaust/intake at BDC) or are there two firing points (magnets/whatever) which means each plug will only fire when at TDC for each cylinder? I can't see seperate wiring for this according to the diagram...
2. Being a V twin I can only see the pick up on the wiring diagram as a single unit and it then feeds the ECU small plug. The two wires going to the coils have the common orange and then two different colours to the second terminal of the coils. Both all look good and have connection, so the problem is pre-ecu or the ECU itself.
3. Has anyone had a fault like this with the ECU?
4. Do the cylinders rotate together (I.E. both at TDC together, or opposite, one TDC one BDC, to confirm the wasted spark theory. If they rotate one TDC one BDC then there may be two pick ups to fire the cylinders....if they rotate together then the wasted spark theory would be more common....being a V twin with alternating fire??, it's fire, fire, suck/squeeze/suck/squeeze...hence the v twin burble??).
Any help appreciated here, bike is now currently round my mates garage who is a forklift mechanic and taken apart. Thanks to another friend on here who ruled out the rest of the bike like TPS etc after plugging it in. Advice appreciated.
Cheers.
 

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Discussion Starter #2
my problem turned out to be the ECU itself, I had the chance of borrowing a unit (which is now sourced) and boom!! Problem solved.
 

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Discussion Starter #4
Thanks for letting us know the outcome. It may help some poor shmuck with the same problem.
yeah was a headache this one, the continuity to the coils was all fine, the pulse drops the voltage to the coils and that then dumps the 12v in coil to earth creating the spark. It's a live 12v circuit all the time the coils but my ECU was not sending the signal to the front cylinder, no.2. Interestingly noboby commented on some of my questions which being on a forum full of guru's....well, I'm sure you'll get what I mean. I could have done some more research like look at the crank diagram and that would have given away the piston rotation etc, but sometimes there's someone that can anwer it all in a moment. At long last the bike is running and now just need some time to go and enjoy it.
cheers Seagoon.
 
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