2013 JD X320 w/ FH661V

[kly5953]

Do you know how old this machine is .. when it was first delivered ? The should be a date-of-manufacture on the VIN plate.
The reason ask is that the early model X300's were having issues with the Electronic Control Module playing up.
It's mounted up under the dash, and when they were "trying to fail", the machines could present with a bizarre variety of symptoms. With some X300's you would swear that it had a fuel system issue, and then the next one you saw with a faulty module you would be prepared to lay money on it being an electrical problem.
That unit had a history of problems, having had FOUR different part numbers since the X300 series was released, and this tends to indicate that the module has had to be revised several times to resolve issues.
Its current part number is AM141075. It might be worth asking the dealership that sold it new to your dad for the machine's warranty history, coz many of these modules failed early in their life. If your unit is the original one then I would change it anyway.
The module swap out is a two minute job.
Let us know how you get on.
Cheers.

The machine was purchased brand new from my father, has never needed to go into the shop.
Pulled the plug on the right side with no change, it immediately died when I pulled the right side pkug(obviously) so hopefully I can swap over the coil pack in the morning and make sure it’s just the coil. I’ll update when I test it.
I will say this, that single cylinder has been providing a lot more power than I would ever have thought, plug looks like it’s rarely been fired, even put in new plugs with no change. Double checked the gap, and when I get that second cylinder firing, I’m definitely excited to feel the power difference.

 

[kly5953]

Good news @OzPete it looks like the coil pack had rattled loose, and its spacing was far enough back the magnet was not sending an ignition signal. I got it fixed this morning and it seems as though it’s running properly.
I pulled the good coil, mounted it on the bad side, fired right up, I then mounted the bad one on the good side and properly set the spacing, turned on the engine, then pulled each plug, noticeable difference. Thank goodness I didn’t need any parts. But I can’t wait to ride and see how much more power it has with 2 cylinders lol

 

[kly5953]

Update:

I went for a test drive on Sunday and realized it is still dropping a cylinder after getting going, though it fires back up intermittently. It seems that the pack is the issue since it is now intermittently working on the other cylinder. SO.....Maybe it has to do with the spacing, maybe it's the coil pack going bad. I will say I eyeball set the gap, didn't put a feeler gauge on it (but I couldn't find the gap online yet anyway) so I will search that unless one of you knows it.

Does anybody have any knowledge of this issue and ways I can trouble shoot it a little better? I'm fairly certain the coil pack is the problem, and when my buddy shook the mower it made it drop the cylinder a bit more frequently so maybe I just didn't tighten it down enough? Heck, maybe the magnet is loose in the coil pack and making this whole thing a headache for me and I just need to get a new one.....any ideas are appreciated!

 

[kly5953]

BTW it's a 651, not 661, my bad on that.

final update:
it was officially just the bad coil pack. I was hesitant to order parts cause I have done that so many times and just wasted money.
Anyways, I swapped the original coil packs' location to test if it was just that. The other side started having the same issues, and the bad cylinder started working properly, so there we go. Ordered a new coil pack, installed it with the proper air gap (~.012" I think?) and it runs like a champ. Good news is the valves are in great shape so no adjustment needed, and now the motor runs good as new.