Ignition coils

[TheFemaleBiker]

So I was on my way to work yesterday and after about 5 minutes or less of riding I suddenly lost cylinders 1 and 4, the whole bike then cut out about 20 feet after that which I think was due to the ignition fuse blowing.

I got the bike home and took it all apart and started testing wires etc, I checked all the wires and everything seemed ok, I changed the spark plugs and the fuse that blew. I turned the ignition on, the fuse blew again so I put a 20amp fuse in and tried again, except when the fuel pump primed I heard a pop (not sure where from, I did have the tank lifted and the air box slightly off) it started up but still only running on two cylinders. I then looked closer at the ignition coil to find this:

I'm not sure if the pop was this breaking or if it cracked whilst I was riding, I'm assuming whilst riding. I've ordered a used coil off eBay. it should arrive this week, which I'm hoping will fix this issue. I thought it was just a little odd is all, the bike has never felt sluggish or anything like that, the engine has always seemed fine whilst riding, for it to just die was rather odd for me. I'm assuming coils just die eventually/burn out or whatever, but my bike is only an 08 model. I was just wondering if anyone else has ever had this at all?

 

[FinalImpact]

Re: Ignition coils // Its Dead Jim!

So, I've seen several forms of electrical carnage but blowing the end from potted ignition coil, that takes the cake there!

When is the last time the spark plugs were inspected?
I'm sure they are mostly OK but damages like that are most often caused when the load (spark plugs) have to big of gap so the coils energy is released internally to itself. This creates heat inside which leads to electrical breakdown of the coils internal wires. Hint: internally there are two copper wires wrapped around a core perhaps a hundred times. When the dielectric coating on the wires fail, it shorts internally and over heats.

That fuse swap may have been the final stray and I'd guess it was the sound you heard as the potting split.

I have a thread you should read when putting this back. It involves verifying the plug caps are snug to the wires.

Can you do me a favor and see if the wires unscrew from the coils? Turn them counter clockwise. You may have to undo that keeper.

Also, if you end up having to reuse the plug caps, it would be wise to verify the ceramic resistor inside measures 10K ohms.

Glad your OK and the shut down didnt leave you in a bad way. I can imagine riding a 2 cylinder I4 was not pleasant.

That SAID; the exhaust may be full of fuel and this could be hazardous when spark is applied. Also an oil change might not be a bad idea. How far was it ridden that way?

 

[ChevyFazer]

Re: Ignition coils // Its Dead Jim!

That SAID; the exhaust may be full of fuel and this could be hazardous when spark is applied. Also an oil change might not be a bad idea. How far was it ridden that way?

Or could make for one awesome start up and a flame thrower exhaust lol

 

[TheFemaleBiker]

It's had an oil change just before winter and I'll be doing another very soo. I checked the spark plugs after this happened, the gaps were only off ever so slightly, by like 0.1/0.2, they seemed ok other than that. Since then I've changed the spark plugs and fitted a new/used coil for cylinders 1 and 4, came with new caps too but it's still only running on two cylinders. I'm going to try swapping the coils over later and see if the issue moves to the other cylinders, but I doubt it will. I'm running out of ideas, only other thing I can think of is the cylinders have too much fuel in and it won't fire.

 

[FinalImpact]

@TheFemaleBiker Are you saying its still misfiring? ((EDIT LOL but it's still only running on two cylinders.)) Im not clear when you said, "I'm running out of ideas". << DERP!
The basic operation is the ignition on, ign fuse powered, run stop switch powered, and with the R/S on, the coils have battery voltage. The others wires to coils are from the ECU and when plugs need fired, the ECU takes those leads to ground.

Have you pulled #4 wire out and checked for spark? Pull plug cap, insert a sparkplug and lay the plug on the exhaust header so the body of the plug makes contact w/the header. Crank engine with run switch on. As you know it can start and run on 2 or even 3 cylinders. You want to see a blue purple arc jump the plugs gap. If there is no spark, now some testing.

Use a 12v test lamp, verify the coils have power on the Red wires. The Run stop switch and fuse are suspect.
To test the ecu: connect your test lamp to battery plus on one side and the orange 1-4, Grey 2-3. Crank engine with run stop switch on, light should blink faintly.

Obviously used parts are also suspect... Verify polarity of coil installed; and I really suggest you test the caps and continuity of Replacement coil. Do you have an FSM? You can verify coil works by quickly supplying it with 12V - and detach. Just brush a test lead over its terminals and it should spark. You have to have the plugs grounded to the Negative side of the battery for this test to work. That said, there is a slim chance the ECU is damaged. But that can be verified.

PS 1 & 4 have the longest leads and should have the Orange wire connected to the coil. IDR which coil is which but on one picture i have the red wire + voltage is on the top. Ground wires from the ecu are on the bottom. IDR if the coils are marked for polarity.

 

[FinalImpact]

Only stuff I have if the coils are not marked...

 

[TheFemaleBiker]

So I fitted the new(used) coil the other day, cylinders 1 and 4 are still not firing. I've swapped the coils over as well to double check the new coil wasn't faulty, it works fine. I have checked the wires going to the coil for 1 and 4, they seem fine. I've cleaned the connections on the ECU with contact cleaner, all the pins on the ECU seem fine too. I starting to think my ECU might be faulty. I have ran the diagnostic thing on the dash, just comes up with the code that indicates cylinders 1 and 4 aren't working/faulty ECU.

Does anyone have any other ideas of what the problem could be? I honestly think my ECU is buggered.

 

[FinalImpact]

- Key on, coils connected, confirm BATTERY voltage at red wires to both coils.
- Key off, ECU connected, Orange & Grey coil wires disconnected from coils, OHM between chassis ground (batt Neg term) and Orange and then chassis ground and red. Tell us the values.
- Key off, ECU disconnected, OHM from Orange and Grey back to ECUs wire connector. Both colors should read the same. Tell us the values.

Off hand sounds like this fried your ECU. That will help point fingers at the fault condition.

 

[FinalImpact]

A quick should out to Martin @Cloggy
Much Appreciated! :thumbup:
http://www.600riders.com/forum/fz6-electrical/member.php?u=673

 

[Motogiro]

That coil looks so bad that there may have been an arc over from the high tension secondary to the low voltage primary side. This may have damaged the switching transistor in the ECU for that coil. Since you've swapped the coils and the replacement is working, the wire should be tested,As FI suggested, to see if it hasn't been pinched and shorted somewhere between the coil and the ECU. Don't run any coil on the failed coil circuit until you've confirmed the wire is not grounded/shorted or open circuit. If that wire is pinched or grounded it could be the reason that coil had such a catastrophic failure where the casing actually burst open. That coil was hot! Rule out a pinched wire that may have started this mess and if that's it repairing the wire may get you back to motoring.

 

[TheFemaleBiker]

I have checked the wiring for that coil, the wiring showed continuity, so I don't think the wire is the issue. If I can find some similar gauge wire, I might try bypassing that wire just to double check but I have a feeling that when the old coil blew it possibly damaged the Ecu.

 

[Motogiro]

I have checked the wiring for that coil, the wiring showed continuity, so I don't think the wire is the issue. If I can find some similar gauge wire, I might try bypassing that wire just to double check but I have a feeling that when the old coil blew it possibly damaged the Ecu.

Make sure that wire has no continuity to ground. The wire could show good from end to end as far as continuity and still be shorted to ground. Disconnect at both ends and check against ground so that you know the wire is not shorting. Do not run a coil on this circuit until you're sure there's no short.
Good idea running your own wire to do a test but if your running the wire parallel and haven't confirmed the original wire is not shorted to ground you will have the same result. I've seen wires burn through insulation inside harnesses and short to a ground or other circuit in the bundle of wires.

Sent from Moto's Motorola

 

[TheFemaleBiker]

Make sure that wire has no continuity to ground. The wire could show good from end to end as far as continuity and still be shorted to ground. Disconnect at both ends and check against ground so that you know the wire is not shorting. Do not run a coil on this circuit until you're sure there's no short.
Good idea running your own wire to do a test but if your running the wire parallel and haven't confirmed the original wire is not shorted to ground you will have the same result. I've seen wires burn through insulation inside harnesses and short to a ground or other circuit in the bundle of wires.

Sent from Moto's Motorola

Yeah, I checked the ground too, it was fine. Did all these checks a couple days ago, so I can't remember the exact figures, but i know there wasn't a problem with the wiring.

 

[FinalImpact]

Make sure that wire has no continuity to ground. The wire could show good from end to end as far as continuity and still be shorted to ground. Disconnect at both ends and check against ground so that you know the wire is not shorting. Do not run a coil on this circuit until you're sure there's no short.
Good idea running your own wire to do a test but if your running the wire parallel and haven't confirmed the original wire is not shorted to ground you will have the same result. I've seen wires burn through insulation inside harnesses and short to a ground or other circuit in the bundle of wires.

Sent from Moto's Motorola

Yeah, I checked the ground too, it was fine. Did all these checks a couple days ago, so I can't remember the exact figures, but i know there wasn't a problem with the wiring.

If you meant to say, "I checked that the wire shows NO continuity to ground," great.

That is what I wanted you to test for and why I asked for the test values. Those resistance values would help us understand the CONDITION OF THE ECU and HARNESS.
​

If not, then its NOT the same thing. With the ECU disconnected and the COIL disconnected, the suspect wire should show INFINITE RESISTANCE TO EVERYTHING ELSE you touch. All wires, all grounds, the battery positive, AND the battery negative. It should have ZERO connection to anything else.


Cliff, in the context that the ECU output only conducts to "ground" and IF, the ignition coil driver wire was shorted to "ground" as we suspect; well if that is the case, I'd almost think the ECU's switching circuit could survive this??? Possible? Well until you add high voltage to its input from the defective coil! Thus making collateral damage!

 

[Motogiro]

Cliff, in the context that the ECU output only conducts to "ground" and IF, the ignition coil driver wire was shorted to "ground" as we suspect; well if that is the case, I'd almost think the ECU's switching circuit could survive this??? Possible? Well until you add high voltage to its input from the defective coil! Thus making collateral damage!

Exactly!!!^^^^ This is exactly why I want to get a cheepo lil scope for my laptop. That way if I suspect this type of damage I can watch the ECU control of the coil/s. But I think I remember reading you suggested a test with a test light. Maybe do the test with an LED because it'll switch really fast and you'll better see (at low crank, the hi-lo state of the ECU coil control. It won't tell us if it's passing intended current needed but still a good go/no go test.

 

[FinalImpact]

Exactly!!!^^^^ This is exactly why I want to get a cheepo lil scope for my laptop. That way if I suspect this type of damage I can watch the ECU control of the coil/s. But I think I remember reading you suggested a test with a test light. Maybe do the test with an LED because it'll switch really fast and you'll better see (at low crank, the hi-lo state of the ECU coil control. It won't tell us if it's passing intended current needed but still a good go/no go test.

Dude, I'm bad as my recent acquisition has a very nice dual rail power supply with +/- supplies to 32V but only a 2A. And 3 scopes! lol None are the greatest but usable...

Ancient CRT 100Mhz Tek Scope 4 ch, a flat panel Tek 200Mhz 4 ch digital storage, and a Fluke portable DMM/Scope Meter battery powered LCD 2 ch scope... It just eats batteries for lunch tho so I'm working on an alternate source/external battery that can feed its hunger! Its also high end DMM Meter! :thumbup:

CRT is the most most user friendly trigger and setup, but not great for packing around!

PS - An LED would be a quick go/nogo test. Great Idea! :thumbup:

 

[TheFemaleBiker]

I'm not very knowledgeable at the electrical side of things as you can probably tell, but surely if the wire was the problem then wouldn't it be blowing the ignition fuse?

The fuse blew when I first broke down whilst riding, the fuse blew again when I tried to start it before changing the coil. But it hasn't blown since I have fitted the new coil.

 

[FinalImpact]

Do you have a hand held meter?

Options;
Buy a $20 meter and test it yourself; - we walk you through it.
Pay someone else to start over and figure it out by throwing parts at it.

The bad coil had a short and the fuse did its job. Mind you the Ignition fuse is between the battery and the coil NOT the Battery and the ECU. So it makes sense that with 2 functioning coils, the fuse lives (for now). I say for now, as it appears the fault which caused this, still exists....

i.e. one of two things likely happened. The ECU died and killed your coil by saturating it with energy non-stop (its not designed to be used that way and it overheated). OR, the wire from the ECU to the coil is shorted to ground and killed your coil by saturating it with energy non-stop.

Testing is needed to determine what is defective.

 

[TheFemaleBiker]

Do you have a hand held meter?

Options;
Buy a $20 meter and test it yourself; - we walk you through it.
Pay someone else to start over and figure it out by throwing parts at it.

The bad coil had a short and the fuse did its job. Mind you the Ignition fuse is between the battery and the coil NOT the Battery and the ECU. So it makes sense that with 2 functioning coils, the fuse lives (for now). I say for now, as it appears the fault which caused this, still exists....

i.e. one of two things likely happened. The ECU died and killed your coil by saturating it with energy non-stop (its not designed to be used that way and it overheated). OR, the wire from the ECU to the coil is shorted to ground and killed your coil by saturating it with energy non-stop.

Testing is needed to determine what is defective.

Yes I have a multi-meter, I checked the wiring once, but I would like to check them again properly at the weekend to determine what the problem is before forking out lots of money for a new ECU which may not solve the issue.

I'm assuming I would need to check voltage and resistance on the wires? Anything else to check? I do have a haynes manual so I can find out what the wires restistance should be etc. I know the coil was getting voltage and remember it being 12.4. I did check the resistance but don't remember what the numbers were/if there was any etc. i feel like a headless chicken sometimes when it comes down to electrical stuff Guidance would be much appreciated, and thanks for your help so far

 

[Motogiro]

I'm not very knowledgeable at the electrical side of things as you can probably tell, but surely if the wire was the problem then wouldn't it be blowing the ignition fuse?

The fuse blew when I first broke down whilst riding, the fuse blew again when I tried to start it before changing the coil. But it hasn't blown since I have fitted the new coil.

You've done a great job of trouble shooting!
We just wanted confirmation on the possibility of a short because you may have still had a short through partial strands in the wire to ground which might not blow the fuse again but instead heat those strands. That would not be good to repeat as this is very often a source for a fire or further damage to other components. We did see that you still had no spark with a replacement coil and if the wire was the source of the problem it would repeat the failure as well as overheating the replacement coil. The source of the coil failure may have well been the ECU to begin with. If the switching transistor in the ECU failed and permanently pulled the coil to ground, the coil primary winding could then overheat and exhibit what you ended up with. So the coil may not have shorted and arced high voltage to the ECU, damaging it, but instead it could have been the other way around. The ECU channel that operated the coil may have failed or the control wire may have shorted and begun the failure. This could have damaged the second coil if the bike was run for a longer period allowing the replacement coil to overheat. Since you had no spark you shut the bike off. That still meant there was a possibility of a ground path through the control wire that was not yet evident because of the time it would take for a meltdown. Once the meltdown occurred again the fuse would then possibly blow if the coil windings shorted and caused a higher than normal current. In the exact same scenario the coil may have just gone to an open winding with no blown fuse.

Think of the fuse as a safety device only and not as a diagnostic tool. Once a fuse blows there has been a problem and the problem should be resolved first if possible.

Another idea with the shorted wire would be that normally the ECU channel that controls that coil would have a high state, meaning it would be at the 12 vdc positive when it is in the off state. The coil primary would be 12 vdc positive at both ends of the primary and there would be no current flow. Then the ECU channel changes to 12 vdc negative and current flows through coil primary. This is the ,"build and collapse" field in the primary coil winding that produces the high voltage spark in the secondary winding. If you had a shorted control wire for that coil channel the ECU control transistor would see higher than normal current for it's design resulting in failure as well as the coil primary overheating.

I know there may be a lot of information to process in regard to this circuit but that is why we ask you to do the tests. Maybe we'd discover another source of the failure and correct it.