JD 425 - Only running on 1 cylinder when cold, and picks up cylinder 2 after 1 min.

   / JD 425 - Only running on 1 cylinder when cold, and picks up cylinder 2 after 1 min. #11  
Last year my JD z915 started popping and backfiring it would do it when the engine was cold or hot. I took it to the dealer since it was still covered under the warranty. They said it was a bad ignition coil. They replaced it and I haven稚 had anymore issues. Hope this helps
 
   / JD 425 - Only running on 1 cylinder when cold, and picks up cylinder 2 after 1 min. #12  
The ignition modules are notorious for being temperature sensitive. I had one that was just the opposite: ran great until it got hot. You could swap the one's you have and see if it moves to the other side. Then you'll know for sure.
 
   / JD 425 - Only running on 1 cylinder when cold, and picks up cylinder 2 after 1 min. #13  
I would recommend replacing both. I wouldn't be surprised if the OP disconnected one of the spark plug wire and it doesn't matter which one it won't start on the other cylinder.
 

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