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The rear cylinder is not firing, bought new coil and replaced still is not working. Any advice as to what to check next, read on line could be ECU, but that is $700 so don't want to replace unless I know that's the problem.
 

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You need to do more electrical diagnosis. Check for +12v at the coils (both of them), just turn the key on and you should have +12v at each coil. The ECU pulses one of the wires by grounding it which then "fires" the coil at the correct time.

That said....if you have +12v and I'm assuming ground is good since it cranks over and actually runs (on one lung), and assuming that it is the correct coil, there are two possibilities. One, throttle body. Two, ECU. Neither is cheap as you already know.

I know...you're thinking, "what do you mean throttle body?" Well it just happens to be that if one of the sensors in the throttle body fails, and you continue operating the machine with it like that, the ECU will default to killing spark to the rear cylinder. Oh how wonderful that was of Kawasaki to design it that way right? Oh but that's not the best part. The best part is that if it's been running a while on one cylinder, like a good length of time, it can take out the ECU as well.

As a dealer tech, the first thing I do is hook up the diagnostic system and read all of the sensor and error codes. Normally if the throttle body has a failure that causes default to one cylinder, it'll show that the throttle sensor or sub throttle has failed numerous times. That is usually the dead giveaway. But as said, replacing it might only fix the throttle body problem but may not solve the ECU's problem, and there really isn't a way to know for sure which is the culprit short of replacing with known good parts. For that reason, you definitely want to test your wiring to eliminate any of that to be problematic before you spend a bunch of money on an ECU or throttle body.
 

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Discussion Starter #4
You need to do more electrical diagnosis. Check for +12v at the coils (both of them), just turn the key on and you should have +12v at each coil. The ECU pulses one of the wires by grounding it which then "fires" the coil at the correct time.

That said....if you have +12v and I'm assuming ground is good since it cranks over and actually runs (on one lung), and assuming that it is the correct coil, there are two possibilities. One, throttle body. Two, ECU. Neither is cheap as you already know.

I know...you're thinking, "what do you mean throttle body?" Well it just happens to be that if one of the sensors in the throttle body fails, and you continue operating the machine with it like that, the ECU will default to killing spark to the rear cylinder. Oh how wonderful that was of Kawasaki to design it that way right? Oh but that's not the best part. The best part is that if it's been running a while on one cylinder, like a good length of time, it can take out the ECU as well.

As a dealer tech, the first thing I do is hook up the diagnostic system and read all of the sensor and error codes. Normally if the throttle body has a failure that causes default to one cylinder, it'll show that the throttle sensor or sub throttle has failed numerous times. That is usually the dead giveaway. But as said, replacing it might only fix the throttle body problem but may not solve the ECU's problem, and there really isn't a way to know for sure which is the culprit short of replacing with known good parts. For that reason, you definitely want to test your wiring to eliminate any of that to be problematic before you spend a bunch of money on an ECU or throttle body.
Yes, a friend of mine tested the voltage everything was good except the ground on the rear cylinder. We couldn't find a schematic to see were the ground went, so at this point I took to the dealer 2 weeks ago and they haven't had chance to look at yet.
 

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The coils have two terminals. One is 12v constant. The other post will also have 12v, BUT the ECU grounds it (the one terminal) when it "wants" a spark. It is grounded for milliseconds. It is not measurable with traditional instruments that most backyard mechanics have. Sometimes trying to do so will destroy an ECU.

Diagnose it by turning the key on and testing for 12v at the terminals of the coil (the two smaller ones). Engine off, key on, they should show 12v on both terminals of each coil.

Dealer will hook up diagnostic stuff and figure it out. Kawasaki's diag software works ok but it doesn't just come right out & tell you where the problem lies, it just gives us the data that we use to make a much more educated guess based on that data. That's the way most diag software works, however, we're all used to automotive stuff which is a lot more conclusive. And yes, I hate the way the system is designed but I understand that there really wasn't a better way in 2006/7 when it was first marketed.

To sum it up, the system is a hybrid alpha-n and MAP system, which doesn't work all that great but its cheap enough (from a manufacturing standpoint) to work acceptably well for them to keep the costs down yet still be useable and meet emissions standards. Kinda complicated aint it? But such is the life of manufacturing....build it as inexpensive as possible to be competitive with the market's other offerings while still metting government standards as well as offering a reasonably long lifespan when used in conditions that it is designed to be used in. :)
 
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