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2015 800 Pro-S , rich at idle, loads up while riding

Mark Earnest

New Member
Messages
6
Age
49
Location
Pa
Country
USA
Years Snowmobiling
20
Snowmobile
2015 800 axys Pro-S
I have a "15" 800 pro-s. It has around 3000 miles. The other day I was riding when half way through my trip the sled started flooding itself out when I would let off throttle then get back in the throttle. At idle it almost chokes me out in the trailer loading it. It drops the cylinders then picks them back up when I open the throttle and give it air. What controls the amont of fuel that is sent to the injectors at idle and when on throttle? Maybe TPS or O2?
 
Maybe broken reed ?
 
Lid1, Would that cause it to run rich at idle?
 
On a carb 2 stroke ? Yes. On a Sdi 2 stroke ? I’m not 100 percent sure. It would really would mess with idle etc. if a reed is broken in therory it would blow some intake charge back out into the air box as the piston strokes but not all and then a carb would introduce even more fuel. I honestly I’m not sure if the same effect is had in a sdi system
 
Tps. Barometric pressure. No 02 sensor stock on sled. Pipe temp sensor is in body of pipe. And is used for fueling adjustments. How is the compression ? Low compression would cause a rich condition. As the suck is reduced and the fuel flow is the same.
 
I will do a compression check tomorrow and report back. On another note today I unloaded it, cleaned contact on 2 relays under hood. They had lite corrosion on them. Ran it up to temp and rode it on our farm for about 5 miles never missed a beat. I hate to role the dice and take it on a trip.
 
How easy is it starting (pull start) ? When my reeds on my Pro R starting going it got very hard to start, had to crack the throttle to get it to go.
Also have you checked TPS adjustment? that controls your fuel and if the base setting is off it will affect idle fuel.
 
Its electric start. It starts perfect but smelled very rich to the extent it would burn your eyes. How do I check TPS adjustment?
 
Try pull starting it when its hot, see what happens. I'd be surprised if its the reeds though in this case since you have the VForce from the factory in that sled, but anythings possible.
As far as the TPS adjustment, it is very common for them to go out of adjustment. The dealer can check it with digital wrench or you can try yourself if you have a very high quality DMM and good backprobing skills.
Someone was selling plug in piggyback TPS harnesses on EBAY to make it easier, which is how i did mine, not sure if he's still around though. Also the sled should be in a warm garage for a while before you do this as temp might throw the readings off.
Below is a thread I found here on how to do it, there is also good info on Snowest and HCS. You should be able to ignore the part about powering up the ECM separately as you have electric start so you can turn the key to power the ECM.

https://polarisstarpower.com/threads/testing-tps-with-multimeter.511/
 
If you could help me find that piggyback harness that would be great. I would like to have that anyways! I own a Auto service center so I have understanding of the importance of the adjustment of the tps. Just for piece of mind I would like to check the setting.
On another note I think I found the problem! I think it was the relays. I found corrosion on them, cleaned the terminals, put electric grease on them and worked great for the short 5 miles I put on them at my farm. I cross referenced the polaris number to a NAPA # (Echlin AR606) I even went a step farther and crossed it to the popular Standard part # (RY612 or the RY612T). Do you happen to know which relay controls the exhaust valves?
 
Could very well have been the relay keeping the valves closed. But that shouldn’t cause a rich condition at idle. UNLESS air was loaded with fuel from riding with valves not open. I’ve seen this when coming to a stop . Valves not opening should have also been causing major rpm issues.
 
Ok so you have done this before and have a good meter. I bought the harness referenced in that thread I posted above but I had a hard time finding the guy selling them a few years ago when I did. This one below should work, also I was wrong you do need a power up cable to power the ECM up. Those are available from SLP #20-212, also handy to power the fuel pump directly to prime after a filter change.
The good news is the newer ones( after 2018 I think) are all auto zeroing like modern cars.
I forgot about the relays since I never had a 800HO motor, went from a 800CFI to my 850. Not sure which one does what, search it there are plenty of threads discussing them. From what I remember reading though, Polaris used cheap chinesium relays in those years that didn't seal water out well so I would just replace them with the NAPA ones or guys were ordering Panasonic replacements from Digi Key I think.

https://www.ebay.com/itm/TPS-Thrott...356876?hash=item3daae8510c:g:QxQAAOSwYkdfWc2F
 


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