If your ECU was seeing fluctuating TPS voltage at WOT while running, you would be able to see that in a gauge Playback.
My take on some Axys rpm/poer loss.
- Thread starter rx1tonofun
- Start date
Supply voltage is staying consistent. Thinking its in the ecu programming or bad ecu. The tps % of opening is what is fluctuating.
I installed a new intake air temp sensor and rode it today. It works better for sure. I think we are having a problem keeping heat in our pipes. After riding it still does the rpm drop at wot and then runs great backing out of the throttle for a bit until I get heat built up in the pipe then it pulls rpm's at wot and maintains them as long as I don't stop and idle it, it seems as long as I've got heat in the pipe it works. I'm encouraged and am happier with the way it's working, I'm seeing progress!
4 Channel lab scope.
You can watch system voltage, 5v ref, TPS output and voltage drop the ground......all at the same time. You can even record it and play it back milliseconds at a time.
Ive done testing like this on street cars, race cars on the track, and snowmobiles making a climb. You can monitor any system you need to... Ignition coils, injectors, map sensor, egt sensor, etc.
Its a great tool to have, and will pay for itself the first time or 2 you use it. no more wasting endless hours and dollars replacing parts that may not be bad.
Just seemed like a good place to share this info.
You can watch system voltage, 5v ref, TPS output and voltage drop the ground......all at the same time. You can even record it and play it back milliseconds at a time.
Ive done testing like this on street cars, race cars on the track, and snowmobiles making a climb. You can monitor any system you need to... Ignition coils, injectors, map sensor, egt sensor, etc.
Its a great tool to have, and will pay for itself the first time or 2 you use it. no more wasting endless hours and dollars replacing parts that may not be bad.
Just seemed like a good place to share this info.
When swapping ECU— make sure the injector color codes (there are three) and oil pump offsets (there are 5) are the same.
I added some injector cleaner this last weekend and the sled ran better. The top 10% rpm variation was lessened and a lot easier to ride with consistent rpm. It's cheap and worth a try.
I've ran it now the last two weekends with a little more weight in the primary and it seemed to work better most of my top rpm loss was gone. I could run 8350-8400 on hard pack and 8200-8300 in the powder. I thought I'd try a little steeper cam(initial angle) and a stiffer sec spring. It didn't like it. I checked the primary and it was showing signs of slippage form beginning to full shift. I've been discussing it with another owner having the same issue. We both agree that if we're not loading the primary and building heat we think that is the rpm loss. There has been discussion of how the stock Polaris weights don't grip the belt hard enough and it slips, I have to agree. I'm not sure what the answer is and I'll definitely try working with the cvt system.
I talked about seeing fluctuation in the tps values before but I can't get them to duplicate. I possibly had a poor connection at the digital wrench port.
I talked about seeing fluctuation in the tps values before but I can't get them to duplicate. I possibly had a poor connection at the digital wrench port.
You guys should contact Rick at North Star performance. I believe he’s on this site as well. He’s got these sled issues figured out.
Worth a phone call as I remember him talking about this issue before.
Worth a phone call as I remember him talking about this issue before.
Do you have any more info on this, where is North Star Performance located? Thanks
RMK-King
Super-Moderator
https://www.facebook.com/NorthstarPerformance137/
He has cured a lot of peoples RPM issues, there is no single answer to RPM loss from what I have found. Some end up being motor mounts, some the PV is not fully open, relay issues, tps, clutches, etc.
Agree that there is no one single answer to RPM loss, mine was mostly clutching. I do not like the straight 40 degree helix, I was not able to squeeze the belt hard enough in the primary to shift out and not slip the belt with 10 series weights, so I changed clutching to load the pipe and squeeze the belt in the primary. I just couldn't load the motor hard enough and keep pipe temp up. I also aligned my clutches with a with the axys cnc alignment tool(motor sits more square in the chassis), keep belt deflection set and set TPS.
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We have been dealing with a cvt issue. We can't load the motors hard enough with the 10 series weights. I tried multiple set ups yesterday in different conditions. I settled on one that kind of worked ask gained elevation it pulled rpm, even at full throttle. At lower elevation I had to back out of the throttle to gain rpm. Lower elevation, more power and the clutching can't load the motor. Higher elevation,less power and easier to load the motor, more pipe heat higher exhaust temps.
Stiffer springs and lighter weight combos to increase rpm don't work with this motor. It likes to be loaded up to build heat and build incredible arm stretching power. As you build more power by stage tuning it's harder to contain the power because they are so damn quick to rev and build power. Once you get your head wrapped around this idea it makes sense.
I absolutely hated my sled last season only because of my ignorance. I have to eat crow, it's actually a great sled.
Stiffer springs and lighter weight combos to increase rpm don't work with this motor. It likes to be loaded up to build heat and build incredible arm stretching power. As you build more power by stage tuning it's harder to contain the power because they are so damn quick to rev and build power. Once you get your head wrapped around this idea it makes sense.
I absolutely hated my sled last season only because of my ignorance. I have to eat crow, it's actually a great sled.
rx1tonofun, keep this alive and let us know what you come up with. I have a 2017 that I am having issues with. At full throttle I am only getting 8100 RPM and if I back out just a little bit I get 8300 RPM. Something's just not right.
My 16 AXYS has slowly been losing power and i have had to lighten the primary up. It has 4000+ kms on it. This weekend I looked into it a bit more and pulled the exhaust valves to clean, do a compression test and ohm the exhaust temp sensor.
When I pulled the valves, I had a bunch of brass flakes wash out of the PTO side. This PTO side turned out to be down to 95 psi compression too, with mag at 105. Exhaust temp sensor was good and pistons looked perfect.
Where is that brass coming from? Water pump gear?
Hope warranty will cover it.
When I pulled the valves, I had a bunch of brass flakes wash out of the PTO side. This PTO side turned out to be down to 95 psi compression too, with mag at 105. Exhaust temp sensor was good and pistons looked perfect.
Where is that brass coming from? Water pump gear?
Hope warranty will cover it.
Hopefully we can do some testing this weekend around 4000-5000' elevation with a 17 and 18 axys. Trying some 69g lightning weights in one sled and a set of the rooster turbo 65g base weights with 2g loaded in the tip. It will be interesting to see if the turbo rooster weights with more mass on the end of the weight works well or not. Also have a few helix angles to try. Both sleds have been running 67g polaris 10 series weight and are not holding R's up top.
