Sucking Air?

sledheader · Feb 6, 2016

Just wondering if anybody else is having this issue. I get an intermittent bog when I wheelie up over a log or out of a creek bed like it is sucking air. It's just a slight hesitation when it wheelies back then it gets back into the power. Am I the only one experiencing this? It has happened since the sled was brand new.

I talked to my dealer about it last weekend and he said he was going to call polaris because he thought maybe the pickup line wasn't long enough. I haven't had a chance to talk to him since to see if he actually called them or not.

ripnit · Feb 6, 2016

Have not had this problem with my Axys but my Pro would do something similar. ...figured out it was the rev limiter. (100 mph max on display)

sledheader · Feb 6, 2016

Mine is 77 on the display and I actually accidentally hit that on the stand before we ever saw snow. Really feels like it's sucking air

It also was doing it real bad on the way back one time doing a couple last minute donuts in the meadow and I was really low on fuel

AndrettiDog · Feb 6, 2016

We recently got dumped on in Colorado. I've ridden four times this week and my sled is showing signs of lack of air. It comes and goes, but it seems that it's not sucking in enough air at times. Funny raspy/gargling noise at times and sled gets hesitant or less responsive. I have the SLP pipe/can and have thought about adding the SLP vents. I didn't want to cut into the dash, but it may be required.

Dootimes2 · Feb 6, 2016

I do not think it could be pick up line. If it is just a quick wheelie over a log it would not use enough fuel to start sucking air through pick up line. Mine has done it a couple of times, it acts like a very quick misfire and comes right back. Only happened a couple times. I have been having some tps issues also. They replaced tps today and we will see what happens. I am also going to take every electric plug connection apart to dry and grease/zip tie them for extra measures.

Murph · Feb 6, 2016

Is the
1) track unloading,
2) causing the crank to spool up too quickly,
3)causing the ECU to momentarily cut power thinking the belt has broken,
4) and then when you reload the track it runs just fine?

Dootimes2 · Feb 6, 2016

Murph said:
Is the
1) track unloading,
2) causing the crank to spool up too quickly,
3)causing the ECU to momentarily cut power thinking the belt has broken,
4) and then when you reload the track it runs just fine?

This is the scenario mine has acted up on.

Sheetmetalfab · Feb 7, 2016

Murph said:
Is the
1) track unloading,
2) causing the crank to spool up too quickly,
3)causing the ECU to momentarily cut power thinking the belt has broken,
4) and then when you reload the track it runs just fine?

I've had this on extremely harsh track unloads while pinned.

Re-entry etc.

Just the motor saving itself.

sledheader · Feb 7, 2016

Murph said:
Is the
1) track unloading,
2) causing the crank to spool up too quickly,
3)causing the ECU to momentarily cut power thinking the belt has broken,
4) and then when you reload the track it runs just fine?

It's not really a full on bog, although sometimes it does become that. Most of the time it's I crack the throttle and I get a "Waaaaaa-brrr-waaaaaaaaaaaaa". Does that sound like what you are describing by pulling power?

Most of the time it is just that short short break in power. Literally so short you barely feel it but you can definitely hear it

Murph · Feb 7, 2016

sledheader said:
It's not really a full on bog, although sometimes it does become that. Most of the time it's I crack the throttle and I get a "Waaaaaa-brrr-waaaaaaaaaaaaa". Does that sound like what you are describing by pulling power?

Most of the time it is just that short short break in power. Literally so short you barely feel it but you can definitely hear it

Without being there and hearing it or riding your sled, I would say yes.

The AXYS ECU samples at a faster rate and the corrections are happening much faster-- that is why the cutouts and rev limiter feel "softer".

I wish there was a little over rev icon on the mfd-- just alerting the operator that the ECU sensed an over rev or over acceleration event. An icon like that would eliminate a lot of head scratching, frustration, and fruitless trips to the dealer.

erik01 · Feb 7, 2016

My sled is doing the exact same thing. I took it to the dealer last week and they did a bunch of stuff and it still does it. They checked the tps, recalibrate the valves, tested my fuel, did a check on the motor and looks perfect. Seems to happen more to me as the day goes on. Sometimes it almost feels like I hit a rev limiter but it's not over revving. Mainly feels like you describe of a quick miss then it comes out of it. It always happens to me jumping off of logs or coming out of something steep and I hammer on the throttle. I find the harder I ride the more it does it

tinkerjohnson · Feb 8, 2016

erik01 said:
My sled is doing the exact same thing. I took it to the dealer last week and they did a bunch of stuff and it still does it. They checked the tps, recalibrate the valves, tested my fuel, did a check on the motor and looks perfect. Seems to happen more to me as the day goes on. Sometimes it almost feels like I hit a rev limiter but it's not over revving. Mainly feels like you describe of a quick miss then it comes out of it. It always happens to me jumping off of logs or coming out of something steep and I hammer on the throttle. I find the harder I ride the more it does it

That sounds exactly like an over rev cond, put the next size heavier weights in and try it

erik01 · Feb 8, 2016

The rev limiter is 9000 RPMs on these motors I believe. The rev limiter is to save the crank. It's not hitting that rpm. I have looked down at the gauge and been at 8150 and does it. I would be getting a DET code if I was over revving this much I would think. But I could be wrong. It's going back to the dealer tomorrow morning. I also rode a friends axys. Same exact sled, stock like mine and I can do the same thinks that makes mine cut out and his wont have a hiccup.

Murph · Feb 9, 2016

erik01 said:
The rev limiter is 9000 RPMs on these motors I believe. The rev limiter is to save the crank. It's not hitting that rpm. I have looked down at the gauge and been at 8150 and does it. I would be getting a DET code if I was over revving this much I would think. But I could be wrong. It's going back to the dealer tomorrow morning. I also rode a friends axys. Same exact sled, stock like mine and I can do the same thinks that makes mine cut out and his wont have a hiccup.

To be clear, there are TWO parameters that can cause the OP description

1) over rev where the motor exceeds the pre set rpm limit-- can sometimes be hard to catch because of how quick the motor revs and the lag time to the MFD readout

2) rate of crank acceleration-- if the crank sensors believe that the crank is accelerating too quickly, the ECU will retard to save motor. When the ECU thinks the motor is revving too quickly, it assumes the belt broke and it is trying to save the motor. This can happen at any rpm-- not only in the above 8000 rpm range

sledheader · Feb 9, 2016

Murph said:
To be clear, there are TWO parameters that can cause the OP description

1) over rev where the motor exceeds the pre set rpm limit-- can sometimes be hard to catch because of how quick the motor revs and the lag time to the MFD readout

2) rate of crank acceleration-- if the crank sensors believe that the crank is accelerating too quickly, the ECU will retard to save motor. When the ECU thinks the motor is revving too quickly, it assumes the belt broke and it is trying to save the motor. This can happen at any rpm-- not only in the above 8000 rpm range

So the first situation you describe is not what I'm experiencing as I know I'm nowhere near 9000 RPM. If fact, I would be surprised to see it over 8000 when this happens. It is no the acceleration up over mounds or logs.

So on the second, would this not be compounded by adding power as in a pipe or can? I wish I had access to another axys so I could see if I could make it do the same things that mine does...

Murph · Feb 9, 2016

Yes, adding power compounds the situation-- even the sled completing break in mode adds power.

Try and find a bump, roller, or something similar where you can unload the track and see if you can replicate your symptom with some regularity.

If you can produce the symptom, add weight to the primary, then replicate your testing method and see if adding weight reduces or eliminates your issue.

Personally, my clutching is set up to where it pulls really well when loaded but if it suddenly unloads it will over accelerate and retard momentarily. I chose not to add more weight because I didn't want to lose rpm when climbing in deep snow or other heavy load situations.

J-pp · Feb 9, 2016

when im doing whellie and the tank is under the half my sled check engine light come on ( det 7 ) so im presuming the pickup swallow air in the tank

xmk1080 · Feb 12, 2016

Murph said:
Yes, adding power compounds the situation-- even the sled completing break in mode adds power.

Try and find a bump, roller, or something similar where you can unload the track and see if you can replicate your symptom with some regularity.

If you can produce the symptom, add weight to the primary, then replicate your testing method and see if adding weight reduces or eliminates your issue.

Personally, my clutching is set up to where it pulls really well when loaded but if it suddenly unloads it will over accelerate and retard momentarily. I chose not to add more weight because I didn't want to lose rpm when climbing in deep snow or other heavy load situations.

So why not try a multi angle helix and load the pipe harder initally? A helix with the same finish angle like a 56-40.36 or a 56-38.36 for higher altitude, I'm going to try these with a heavier heel weight but it will be at thee weeks before I can test!

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Sucking Air?

sledheader

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ripnit

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sledheader

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AndrettiDog

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Dootimes2

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Murph

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