Kohler Command ignition module?
#1
06-17-15, 06:21 AM
Kohler Command ignition module?
I have a 20 year old Toro Proline with a Kohler Command CH20QS engine, and 800-900 hours. It takes me maybe 2-1/2 hours to mow the lawn, and, new this year, each time I mow I have about a 30 second stretch when the engine loses power. Keeps running, but the RPM's drop a bit, and it feels sluggish, so I stop, disengage the blades, throttle it down, let it idle 20-30 seconds, rev it back up, engage the blades, and it continues flawlessly. It got new plugs, air filter, etc. this spring, and because I had to replace one of the head gaskets a few years ago, checked the compression, and everything looks good. So am now thinking that maybe one of the ignition modules is going bad. My plan now is to pull one of the plugs today, with it running, and see if that replicates the sluggishness. If it does, then put a fuse puller on the mower, so that the next time it does this while I am running it I can pull one of the plug wires to see if that is indeed the problem. Assuming this is the problem, is there any reason to change both modules, or just the bad one? Make sense, and/or any other thoughts?
#2
06-17-15, 10:02 AM
Forum Topic Moderator
Makes sense. If you determine one cylinder is skipping, I would put an inline spark tester in next so that you can visually see if there is spark or not when this happens.
#3
06-17-15, 10:36 AM
Thank you. Don't use the spark tester too often, so hadn't thought about it, but now have it and the fuse puller laying on the seat of mower. Also ran it just a bit with one plug wire pulled off, and yup, same exact scenario. In fact, will still do the test when I mow next, but am sure enough that I'm on the right track, I took a leap of faith, and ordered a pair of modules a little bit ago. Heck of it is that actually replacing the modules is simple, but it's getting the engine unbolted, the muffler guard and all of that out of the way, finally getting the fan cover off, and everything back together that turns it into a half day job. So, figured I may as well spend the extra now and be done with it. If I find something else, will only be out the shipping to return them. We've been getting so much rain that the grass is already growing faster than I can keep up with, so don't want to have it down twice. Thank you again.
#4
06-17-15, 06:00 PM
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If you haven't, you might pull the plug wire on each side one at a time and make sure you get the same results on each cylinder.
I don't believe I have ever seen a coil go out for a short time then working again without some extended cool down period.
It would also be a good idea to check your valve clearance, especially on the side the head gasket was replaced on. A compression test will not show a valve that is not opening, but a valve not opening will keep that cylinder from working.
I don't believe I have ever seen a coil go out for a short time then working again without some extended cool down period.
It would also be a good idea to check your valve clearance, especially on the side the head gasket was replaced on. A compression test will not show a valve that is not opening, but a valve not opening will keep that cylinder from working.
#5
06-18-15, 06:22 AM
I like the idea of pulling each plug wire, and may do that yet, except that access to the back plug requires removing the fuel tank on this one, so need to get creative to do it. And I agree on thinking a coil problem wouldn't resolve itself that quickly, but have found a few posts and articles on the web that seem to say that is exactly what they ran into. Also would agree with a possible valve train issue, but it has hydraulic lifts, no adjustment, and I think that say a burned valve or whatever would be more pronounced, so am sort of skirting that possibility for the time being. I appreciate the thoughts and suggestions though. Thank you.
#6
06-18-15, 10:33 AM
Forum Topic Moderator
These engines do occasionally have valve problems, but normally it's a seat that pops out of the head and falls out of place sporadically and back in place sporadically. Thing is, when that happens, you normally get pops and backfires. I'd suspect a coil or possibly even carburetion from your description. Despite what it seems, the carburetor can make one cylinder weaker than the other. I had one that came to me 4 different times for one cylinder dropping when it got hot and I replaced the coils and plugs and the last time I put it out in the field and mowed with it for a long time until it acted up so I could experience the problem myself. It wound up being a carb problem.
#7
06-18-15, 10:56 AM
I mentioned that I thought a valve problem would be more pronounced, and the popping and/or backfiring was what I had in mind, so anything is possible, but yes, would expect that sort of thing if a valve were burned. Will keep the "floating seat" scenario in mind though. Interesting on the carburetor. Ironically, I was thinking recently that I have never had to even touch the carburetor in 20 years, but did not consider it a possible candidate in this case. Do want to get it running right again, but sort of wondering why because I probably should be replacing it. Came close last year, until one of the local dealers jacked me around a bit after I told him to order one, but I bought this one new, and has always done a great job, so am going to hate to part with it.
