Fouling spark plugs on cold start

[HpPerformance]

I fouled 3 spark plugs on cold start ups in the mourning as soon as i pull on the dam cord this year. I have a 2019 Rmk 850 with almost 100h on it with the 2019 reflash, i do not get the random bog anymore, but i still foul plugs like crazy, 6 plugs already this year and i have only been out 5 times. While i'm riding it will bog just before the spark plug is completely fouled (like if it's getting to much fuel on one cylinder or something). If anybody has or had these symtomes please let me know if you have found a solution.
P.S. I ride between 1000-3000ft in elevation

 

[klarkkentster]

Were you able to come up with a fix?

 

[Jaynelson]

Not a comprehensive list, but 3 things to investigate:

- Has the most recent reflash been completed?
- It's possible the injectors are leaking down, have seen that before
- Do you have a can, specifically GGB? If so, try it with the stock muffler.

 

[klarkkentster]

Just had the latest flash.

Not sure on the injectors. Hope the dealer checks that. That actually makes sense.

SLP can.


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[Chadly]

What is the temperature when you are starting the sled in the morning? If it's it 20 or less unplug the fuel pump until you get the sled running.

 

[klarkkentster]

I need Polaris to fix the sled -have no interest on having to jump through extra hoops on a sled with 265 miles.

 

[Sheetmetalfab]

I need Polaris to fix the sled -have no interest on having to jump through extra hoops on a sled with 265 miles.

Accidentally light it on fire?

 

[Chadly]

Then you should just buy a Ski Doo. You probably aren't good enough to ride a Polaris anyway ?

 

[Jaynelson]

Seeing that it’s easy to do without visiting the dealer...try a ride or 2 without the SLP can and see what happens. Have quite a few out there running great with SLP cans, but recently had 1 that didn’t like it. Guessing it is a difference in temp on the exhaust probe in can vs stock muffler.

If that doesn’t help, Im guessing injectors. Definitely have replaced a “greater than zero” number of 2019 850 injectors.

 

[takethebounce]

The 21’s are definitely running with a rich like condition even after break in at lower RPM’s.

I have fouled two plugs on cold start up offloading from the truck. Stock can and GGB Quiet can, very similar in design to SLP but temp probe is in the neck. Started sled, engine says cold and started running rough before engine temp came on and went to move the sled and it was running on one cylinder. The plugs were soaked. Okay I can understand during break in it happens.

But they are running with a rich like condition all day, out of break in. Outside temps are -2c to -15, so not extreme colds, elevations anywhere from 3500-6500’. When riding at lower rpm, or after climbing and descending and blip the throttle for compression braking they are loading up and running rough. Riding slower, picking your way through the trees again it takes a second or to for them to clean out when you get on the throttle. Once on the throttle they are running just as expected with no concerns.

The operating temps during this are very low as well at 34 (100ish).

When I ran the stock can I chalked it up to break in, but now after trying a GGB and a SLP can, they all run similar. I am going to try the stock can once again to eliminate that but I am not sold on it being an issue of some sleds not liking some cans when the same condition is present regardless of the can.


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[Jaynelson]

The 21’s are definitely running with a rich like condition even after break in at lower RPM’s.

I have fouled two plugs on cold start up offloading from the truck. Stock can and GGB Quiet can, very similar in design to SLP but temp probe is in the neck. Started sled, engine says cold and started running rough before engine temp came on and went to move the sled and it was running on one cylinder. The plugs were soaked. Okay I can understand during break in it happens.

But they are running with a rich like condition all day, out of break in. Outside temps are -2c to -15, so not extreme colds, elevations anywhere from 3500-6500’. When riding at lower rpm, or after climbing and descending and blip the throttle for compression braking they are loading up and running rough. Riding slower, picking your way through the trees again it takes a second or to for them to clean out when you get on the throttle. Once on the throttle they are running just as expected with no concerns.

The operating temps during this are very low as well at 34 (100ish).

When I ran the stock can I chalked it up to break in, but now after trying a GGB and a SLP can, they all run similar. I am going to try the stock can once again to eliminate that but I am not sold on it being an issue of some sleds not liking some cans when the same condition is present regardless of the can.

Have heard of what you are experiencing on the 21's, yes, and back to the 2019's as well. On the 21's I will chalk it up to mapping for now, but the 2019's (that OP is having issue with) were a bit notorious for bad injectors, which would similarly foul plugs mostly on cold start (and other times). I have not fouled any plugs in either of the 21 sleds I've broken in, but it has happened to a fella I know. No injector issues on 21's so far, or 20's (from memory).

Regarding cans.....it seems some run a little richer than others, and if one is "on the edge" of fouling plugs, the stock can might just make the difference. We had a 2019 that couldn't keep plugs in it with a GGB - put stock can back on, now hundreds of kms on same plugs. It seems some will foul plugs regardless of can, some will NOT foul plugs regardless of can, and some it will make that difference. Not a bulletproof answer or diagnosis by any means, but it's an easy variable to eliminate.

 

[klarkkentster]

Have heard of what you are experiencing on the 21's, yes, and back to the 2019's as well. On the 21's I will chalk it up to mapping for now, but the 2019's (that OP is having issue with) were a bit notorious for bad injectors, which would similarly foul plugs mostly on cold start (and other times). I have not fouled any plugs in either of the 21 sleds I've broken in, but it has happened to a fella I know. No injector issues on 21's so far, or 20's (from memory).

Regarding cans.....it seems some run a little richer than others, and if one is "on the edge" of fouling plugs, the stock can might just make the difference. We had a 2019 that couldn't keep plugs in it with a GGB - put stock can back on, now hundreds of kms on same plugs. It seems some will foul plugs regardless of can, some will NOT foul plugs regardless of can, and some it will make that difference. Not a bulletproof answer or diagnosis by any means, but it's an easy variable to eliminate.

I may end up running the stock can fit a bit. We’ll see what the dealer comes up with. Any idea if they replace the injectors - if they are an updated version? I’m assuming the injectors are bleeding down causing the fouling between rides.


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[klarkkentster]

Then you should just buy a Ski Doo. You probably aren't good enough to ride a Polaris anyway [emoji854]

Do you honestly feel that is a viable option on a near new sled? These are fuel injected engines that should be able to overcome temp and altitude. If those are actually necessary work arounds - I don’t think skill is a determining factor of brand choice, more likely intelligence and tolerance.


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[Jaynelson]

I may end up running the stock can fit a bit. We’ll see what the dealer comes up with. Any idea if they replace the injectors - if they are an updated version? I’m assuming the injectors are bleeding down causing the fouling between rides.

Don't recall sorry. Seems like more of a QC/production run thing on injectors supplied at build time vs faulty design. I wouldn't be too worried even if it's the same part # going back in.

 

[takethebounce]

Have heard of what you are experiencing on the 21's, yes, and back to the 2019's as well. On the 21's I will chalk it up to mapping for now, but the 2019's (that OP is having issue with) were a bit notorious for bad injectors, which would similarly foul plugs mostly on cold start (and other times). I have not fouled any plugs in either of the 21 sleds I've broken in, but it has happened to a fella I know. No injector issues on 21's so far, or 20's (from memory).

Regarding cans.....it seems some run a little richer than others, and if one is "on the edge" of fouling plugs, the stock can might just make the difference. We had a 2019 that couldn't keep plugs in it with a GGB - put stock can back on, now hundreds of kms on same plugs. It seems some will foul plugs regardless of can, some will NOT foul plugs regardless of can, and some it will make that difference. Not a bulletproof answer or diagnosis by any means, but it's an easy variable to eliminate.

Yes I just saw that they are still having the issue and didn’t feel it was worthy of starting a new fouled plug thread.

I can agree that can “A” may be amplifying the issue on one sled and can “b” doing the same on the other but the issue is still there and it’s not just my sled in my group. Some guys are very frustrated by it. I am just trying to work through it and see what if any rider induced cause has a larger impact.

I am not fouling plugs while riding which is fine but that lack of performance is where it needs to be fixed for those moments when you hit the flipper and need to spin the track around to avoid a creek hole because it is running dirtier than your sister cousin from Salmo. Lol


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[Over budget]

Do you honestly feel that is a viable option on a near new sled? These are fuel injected engines that should be able to overcome temp and altitude. If those are actually necessary work arounds - I don’t think skill is a determining factor of brand choice, more likely intelligence and tolerance.


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Easy Klark. I think chadly was just poking a little fun. ?

 

[klarkkentster]

My bad - i'm sure you can imagine the frustration of being in the heat of sled season and have a sled - thats almost new - in the shop with no sign of when it will be completed. Just chatted with another guy with the same year sled - very similar issue - fouled plugs from the get go for 300 miles and then finally seized. Was a failed crank seal - Polaris fixed it but he was without a sled for over a month. Has anyone heard of Polaris offering incentives with a broken sled under warranty to transition into a new one?

 

[Teth-Air]

Running hotter plugs definitely helps if it loads up when on and off the throttle at lower speeds. And the latest 2020.5 flash is the leanest so far.

 

[die hard poo]

I notice on the 850s is if you try and move the sled off the trailer without letting it get out of cold start, you will almost certainly foul the plugs, the sled will go into limp mode basically if the engine is still below the 65*ish coolant temps. I have since let the sled warm up till it doesn't say cold engine on the gauge, then I proceed with getting it off the trailer.

 

[klarkkentster]

I notice on the 850s is if you try and move the sled off the trailer without letting it get out of cold start, you will almost certainly foul the plugs, the sled will go into limp mode basically if the engine is still below the 65*ish coolant temps. I have since let the sled warm up till it doesn't say cold engine on the gauge, then I proceed with getting it off the trailer.

I have been letting it get to at least 100 degrees before even touching the throttle. Still fouled. I think my dealer is close to a resolution.


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