Cylinder 2 Coil Circuit Error

Here be mechanigeeks. Anything technical that is not a teething problem.
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Grim Reaper
125cc
125cc
Posts: 5
Joined: Sun Nov 10, 2019 7:25 am
Country: United Kingdom
City: South Essex
Year: 2010
Colour: Black
Model: SMT

Cylinder 2 Coil Circuit Error

Post by Grim Reaper » Sun Nov 10, 2019 7:31 am

Okaaaayyyy....here goes, I put this on the KTM forum as well so hopefully someone here can offer some advice. Didn't realise this forum existed until I started my research into my problem but I'm glad I have found a forum dedicated to these bikes....the story so far, and I've left as is so you get the full picture. I'm still researching too......

1st post

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.

2nd post after reading how the spark is created at the coil.....

Soooooo, yesterday we did some more investigating. When the ignition is on there is voltage across both coils which at first seems odd. When the ignition turns on so does the feed to both coils, I'm assuming this is normal for the bike as cylinder 1 has it and it's still firing fine. We also checked the reading of the sensors on the exhaust for both cylinders and the reading is exactly the same to it can't be a sensor telling the cylinder to fire/not fire. Also checked the continuity of the common orange wire which feeds a few other sensors and things and that was good throughout the loom. This is what gives the voltage feed to the coils, sensors and so on (it's all on the wiring diagram). My next step is to either get my ECU tested (does anyone on here know where I can get this done ??) or try and borrow an ECU from a superduke, apparently they have less problems and do away with some of the function of the SMT one, I'm going to do some more research on this. Again, if anyone can shed light please do

thnaks

Update: I've read up that the coils are live feed and the spark is created with the ecu get a signal from the pickup and cuts the voltage, this causes the coil to dump power and cause the spark. So something is failing to tell my ECU to spark at the front cylinder. NOW i need to find out if there are two points that make it fire or one with a wasted spark. Does anyone know ?? this would help me with my investigation and where to look next or whether to get my ECU tested. If there are two firing points, i.e. the ECU gets two pulses from the pick up then one circuit is good and the other not, which is to the front cylinder. If it only gets one pulse and has a wasted spark then I could be looking more towards the ECU......I am continuing to research.....

Grim Reaper
125cc
125cc
Posts: 5
Joined: Sun Nov 10, 2019 7:25 am
Country: United Kingdom
City: South Essex
Year: 2010
Colour: Black
Model: SMT

Re: Cylinder 2 Coil Circuit Error

Post by Grim Reaper » Sat Nov 16, 2019 8:23 pm

Sussed. Lucky enough to acquire an ECU to rule it out and boom!! problem solved. I will leave all this on here just in case someone else gets the same problem, after all the continuity checking and so on and it turns out the ECU was the faulty component. Replaced and now starts on button and runs as it should. Thank fuck for that.
:twisted: :mrgreen:

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