2016 Turf Tracer w/ Kohler Misfiring...Driving Me WILD

Discussion in 'Mechanic and Repair' started by mattc358, Oct 24, 2018.

  1. mattc358

    mattc358 LawnSite Member
    Messages: 7

    I'd like to note that I've spent 15 years working on engines from minor repairs to full rebuilds (bought an 09 Subaru legacy from a kid that drove it without oil, rebuild and now daily that vehicle) so there is a reasonable amount of experience (so I like to think).

    I have a 2016 Exmark Turf Tracer 60" X Series I recently acquired. Kohler ECV650-3017 EFI. Worked great for the first few cuts, maybe 5 hours. In general, pretty good shape. About 1170 hours on the unit. Engine oil is new and full. Hydraulic oil is in the proper range (not that this applies right now). I'm terrible at explanations (too much info usually) so TLDR at the end.

    One day I started it and we were running one 1 cylinder (the operator's left cylinder was cold). Let it warm up for a few minutes, the cylinder would kick on and we'd have full power. I cut the yard and moved on.

    Next time, I was on 1 cylinder again (left cylinder cold). It looked like my left cylinder had no spark, so I got new Kohler coils. This fixed it for a cut or two. Then back to 1 cylinder (left cylinder cold). I took off the new coil, and installed the new "good" coil (from the right cylinder). Worked great.

    Then we are back to the same old BS after a cut or two. Left cylinder cold. Thought I burned up the left coil, so I did some homework. I bought a new Kohler regulator/ rectifier based on the reading I've done.

    ANYWAYS, new R/R didn't help. I've got solid spark on the left though. While the engine was running on 1 cylinder, I sprayed the airbox with engine starting fluid and there was no difference. This tells me fuel is not an issue. The strong spark I saw tells me the spark is not an issue. I tested all the coils, and they have the same resistance values for primary and secondary coils. There is continuity throughout the block for ground (sounds silly, but I know funky ground connections cause real funky gremlins). The ground wire from block to battery is solid. New Sparkplugs, too.

    TL;DR Coils test as good. New plugs. New Regulator/ rectifier. Engine will run on 1 cylinder randomly, yet is somewhat consistent (engine runs steady on 2 cylinders or 1 cylinder). When running on 1 cylinder, starter fluid sprayed into the airbox makes no difference.

    Confused to death. Help?
     
  2. Walker56

    Walker56 LawnSite Silver Member
    Messages: 2,019

    When this situation occurrs, have you pulled the plug on the left cylinder? Is it wet or dry? If the plug is wet, you could have a compression issue possibly from a sticking valve or a sticky lifter. I would perform a compression test when the left cylinder is in a non functioning state. If the plug is dry, it could be an injector or a wiring issue. Here is a link to the service manual
    http://resources.kohler.com/power/kohler/enginesUS/pdf/24_690_02_EN.pdf
     
  3. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,426

    Needs a wiggle noid test.
     
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  4. mattc358

    mattc358 LawnSite Member
    Messages: 7

    I've been suspecting a valve issue of some sort for sure. A stuck valve may be the ticket, I'll open it up when I get time. Ricky, if you're willing to elaborate on a "wiggle noid test" I'm all ears. I see plenty of search results for a noid light to test fuel injectors, but nothing on a wiggle noid test...
     
  5. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,426

    A test light should blink when the engine is running. If wiggling the lead stops it, you have a wiring problem.
    Stuck valves, most of the time, will backfire...loud.
    It's not a common problem on Kohlers.
    Unless the maintenance is extremely poor.
     
  6. Rockbridge Lawn Care LLC

    Rockbridge Lawn Care LLC LawnSite Senior Member
    Messages: 896

    my money is on a wire short some where. a little heat can melt the insulator and cause an intermitten ground. Also I believe a bad coil or injector would pop a code on the operator screen. turn the key to "on" position and it'll give you a 4 digit number if there is a code. you can google search that code or talk with Kohler.

    It could also be a bad EDC which sends the signal to the coil pack to "fire" and that signal travels through all the wiring and can't have any shorts along the way. The fact that you switched the coil packs with-out change in running indicates that the problem is prior to the coil packs....which is the EDC (engine diagnostic control)......

    a new O2 sensor would also help balance the fuel circuit should it be lean or rich.

    Or a 90% blocked fuel injector could also feel like a mis-fire as there practically is no fuel in the combustion stroke. I don't know how much starter fluid in the air box would richen the mixture...and if so can you hear the difference in your air box test...? IMHO I think that is a long shot in a diagnostic prospective, but food for thought.


    and EDC is expensive as its the brain box....not sure if you can test them, I'd have to read up on that aspect.
     
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  7. Walker56

    Walker56 LawnSite Silver Member
    Messages: 2,019

    Become familiar with the manual that I posted a link to as there are two different EFI systems.
     
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  8. Rockbridge Lawn Care LLC

    Rockbridge Lawn Care LLC LawnSite Senior Member
    Messages: 896

    here are the specialty tools for EFI troubleshooting from the manual.. also should read the first 50 pages to cover the EFI/ECV information- thanks to walker for the link

    upload_2018-10-26_10-15-33.png
     
  9. Rockbridge Lawn Care LLC

    Rockbridge Lawn Care LLC LawnSite Senior Member
    Messages: 896

  10. mattc358

    mattc358 LawnSite Member
    Messages: 7

    You guys are outstanding, thank you for all of the knowledgeable replies!

    I suppose a stuck valve would make a loud backfiring sound and if it's firing (at all) the cylinder should get hot or at least warm- this isn't happening right now. I can't make any promises about maintenance before it was in my posession, but I've learned the hard way in the past to avoid buying trashed vehicles. I try to buy seemingly well kept equipment

    But if the issue is a lack of fuel, the starter fluid should have brought the left cylinder back online (temporarily) and there was no response whatsoever. That's part of why I was so confused.

    I've got a lot of information here to chew on, and right now I've been spending my time renovating houses. I will digest everything you guys have given me and do some further testing/ diagnosing on the mower as soon as I can. Thank you so much!
     
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