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Discussion Starter #1
We recently traded in both of our 2015 570 Sportsman EPS's for the same. With 3 hours on them, one misfires between 4100 and 4400 RPM's no-load or light load. No backfires, but close. The 2015's never had this issue. The other new ATV misfires less often and below 4000 RPM's. Gas is premium non-ethanol, plug wires tight, etc. Unlike many on these postings, we have a local dealership that is technically excellent. I took the problem one in to the dealership today, and it misfires the same as their new floor model. Mine: 4 hours. Floor model: 0 hours. It starts well, ALMOST backfires at the 4000-4400 RPM range with light load, but has no acceleration or other issues with the engine. The service dept is certain that the electrical is good, and fuel pump pressure is good. That leaves a fuel issue and "all 2020's are the same". Here's my thoughts: We're at 6000' elevation (though it repeated at 5000' at dealership) and running the best (slowest burning) gas possible. Am I experiencing pre-ignition? Or missed ignition? Should I try a cooler spark plug? Hotter one? Something else? More break-in needed? Thanks for your ideas!
 

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I'd make sure they document the issue and then run it pretty hard for a few hours/miles to see if there's any improvement. Make sure they understand you expect it to be corrected sooner rather than later if it don't straighten up on its own.
 

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Discussion Starter #3
Excellent idea. Thank you. I verified that it is documented, and I think if trying a hotter plug, a colder plug and a few more hours doesn't help, I'll first insist that the service manager places a call to the factory. Something has changed in the five years since we got our first 570's.
 

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2019 sportsman 570
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I have a new 2019 570 sportsman with 2 1/2 hours on it and mine does not have that issue. When I brought mine home I replaced the plug with a ngk.
 

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Discussion Starter #5
MR7F? MR8F? Did it have a Champion in it from the factory? Any particular reason you replaced it?
Thank you
 

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Discussion Starter #7
Ok. I'll have the MR7F in it tomorrow morning and will report back. The back recesses of my fading memory also tell me to avoid Champion and use NGK's. Thank you.
 

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Discussion Starter #9
So far....pulled the original plug. It was a NGK MR7F gapped at 0.030". A bit dark in color. I had a new one (same NGK MR7F), I gapped it to 0.035", installed, ran it, and no changes. I added a cooler plug, NGK MR8F at 0.030", and it ran worse (more sputtering, more often, no backfires). My last thought is to get a hotter plug MR6F and try that.
 

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Discussion Starter #11
I think you're right. I pretty much have two options left: Hotter plug, or more breaking hours (4 now). Then, lean hard on the Service Manager to contact Polaris and fix this before the warranty period is up...
 

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Discussion Starter #12
Here's the latest....I swapped plug and plug wire between sputtering ATV and non-sputtering ATV. No changes. Actually, the "non" sputtering one sputters a little bit at a lower rpm (3600-4000). Acceptable. I drove a friends' 570 EPS. 2017 with a hard 350 hours on it. Sputters worse than our worst one, and he never noticed it because he doesn't often stay at a constant RPM. Now, it bothers him also. So, I'm leaning more and more to a programming issue with the EFI. And, perhaps elevation-related here at 6000'. The stock NGK plug is a MR7F. The next range cooler is MR8F. However, one cannot get a MR6F hotter-than-stock plug. The closest option is NGK CPR6EA-9 which is similar in all specs, but stands about 0.1" higher above the head. Perhaps the female plug wire stinger will stand up 0.1" higher also, and there won't be a good dust and moisture seal between top of head and recessed plug. Waiting for new plug and will report back.
 

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I would give Ryan from RVS PERFORMANCE a call he deals with efi issues all the time. He really knows what he is talking about!!!
 

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So gregs for your issue I would work with your dealer and Polaris for the time being. but your buddy and im assuming hes out of warranty he should get a tune from RVSPerformance. remember these machines are tuned for compliance from the factory not efficiency.
 

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EFI is supposed to compensate for air density automatically - carbs have to be jetted down above 4000 feet or they run too rich. What makes you think changing the heat range of the spark will affect a running condition? The heat range refers to the temperature the tip of the plug runs at when the engine is at normal operating temperature. The spark is the same intensity and temperature regardless of the heat range of the plug. Too hot; the plug can cause pre-ignition and lead to engine damage - too cold and it may foul more often - you can always run colder than recommended safely and going one step hotter is usually safe, but go two steps hotter and engine damage may happen especially when running at a constant or high speed. If after about 20 hours of operation the plug porcelain at the tip is tan, the heat range of the plug is right, black is too cold and white is too hot.
 

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My 19 570 doesn’t have any kind of sputter, that I have noticed at any rpm. From 4 hours till the now 27 hours. It runs great down here at sea level.
 

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Discussion Starter #17
Latest update on the misfires--latebird is right about the spark plugs. However, they were one of my only easy-swap options, and one range cooler and one range hotter plugs didn't solve the misfiring problem. Both the new problem ATV and new non-problem ATV's are at the dealer now (5 hours running time total each). Since the floor model they tested has the same misfiring issue, I thought they could swap parts between our two ATVs if they needed to further isolate the issue. The service manager will be working with Polaris factory on solving this. The dealership is 45 minutes away, so I try to do as much at home as possible before taking two round trips with a trailer. Stay tuned....
 

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Latest update on the misfires--latebird is right about the spark plugs. However, they were one of my only easy-swap options, and one range cooler and one range hotter plugs didn't solve the misfiring problem. Both the new problem ATV and new non-problem ATV's are at the dealer now (5 hours running time total each). Since the floor model they tested has the same misfiring issue, I thought they could swap parts between our two ATVs if they needed to further isolate the issue. The service manager will be working with Polaris factory on solving this. The dealership is 45 minutes away, so I try to do as much at home as possible before taking two round trips with a trailer. Stay tuned....
Any update on how you made out?
 

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Discussion Starter #19
Any update on how you made out?
It has been at the dealership for a month now. I wrote a certified letter way up the chain at Polaris, and now the factory support folks are involved. Pretty frustrating, but I think they'll get to the bottom of it. Thanks for asking
 

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It has been at the dealership for a month now. I wrote a certified letter way up the chain at Polaris, and now the factory support folks are involved. Pretty frustrating, but I think they'll get to the bottom of it. Thanks for asking
You should of asked for a "loaner" to ride while those numb skulls figure out the flaws. Unless I'm really overthinking it.....I bet you any money that Latebird is pretty close to where the problem may lay/lie. I wouldn't be surprised that the ECU/programming/sensors/etc aren't programmed to assess elevations that high. I would assume they are selling a majority of machines all programmed the same way across the board to handle...let's say...(somewhere in the middle baseline) type of altitudes and conditions right?....But what happens when a customer rides their machine to an altitude beyond the somewhere in the middle baseline? I would assume that sh*t doesn't/wouldn't work right. It may need a programming tweak/reflash. The only other thing that I can think of that might help out (based on my limited tinkering around with my fuel controller from HMF) is that you can get an aftermarket fuel controller and it may be your solution after a bit of tinkering/tweaking of settings. As you may or may not know, fuel controllers can typically "set/change the signal to the fuel injector to compensate (to a certain point) for changes in air density such as temperature, humidity, and elevation. Since the computer cannot see intake air volume or monitor the oxygen content in the exhaust, it does not know additional fuel is needed"
(See below for some literature I snagged from the HMF site). Regardless, good luck with everything. Please let us know how you make out.
 
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