Running rich at altitude?

[polemite.productions]

thought i'd ask the audience before i go randomly digging-

seems like my sled isn't adjusting the fueling for altitude. once i'm up there, it idles high, and i often need to crack the throttle when restarting. anyone been down this road already?

i seem to remember that the ecu samples the air through a tube hanging out of it. i was going to check to see if that's plugged. beyond that, i'm kinda shooting in the dark.

 

[polemite.productions]

been thinking and reading about this some more, and i'm beginning to wonder if it's more related to temperature, rather than altitude.... intake air temp? coolant temp? exhaust temp? could be any or all of these things, right?

 

[spoon]

Underhood temps in general. Does this happen in deep powder? Warm/cold days. Check air temp sensor for covered in crap and insulating it.

 

[polemite.productions]

no, i wouldn't pin it down to ambient temps or snow conditions. i just seem to notice it once i'm up the trail. but now i realize that i generally don't shut it down between the parking lot and the riding zones. so it could easily just be the difference between a cold start and a warm start. if the ecu doesn't realize that we're now at operating temp, it's likely still adding fuel as though it were a cold start. i'll have to check all the temp sensors.

 

[spoon]

A lot of times if sled is being shut down immediately after a good load (trail riding uphill, boondocking etc) without a bit of an idle down it sometimes will dump a bit of extra fuel in and when restarting it needs that extra air to fire up immediately. Mine always seem to idle high at altitude (5000+ft) and normal at the truck (2000ft).

 

[polemite.productions]

yeah i would imagine. but i always let it idle down. i seem to have the same high idle at elevation that you have. odd.

 

[boondocker97]

Had my barometric pressure tube freeze off one time and the gauge was stuck at an incorrect (lower) elevation than what I was actually riding at. Was making it run noticeably richer throughout the RPM range not just at starting. Mine idles high at low altitude and normal up on the mountain. I didn't do this when it was new, but for some reason it changed at about 1000 miles and been that way since. Intake air temp can affect starting (why there are sensor relocation kits) and water temp can affect it.

 

[spoon]

On my older boosted 1000s, I needed a switch on my water temp sensor to trick the computer into adding fuel as on some hot shutdowns it would pull all fuel and then a no start until it cooled down or you added fuel into cylinder or unplugged sensor for 1 pull (duplicates -50 cold start). Only seemed to happen on modded engines especially turbos. Switch does same as unplug and will flood engine if not careful. Heat soaked temp sensor could be possible issue with your restart issue is what I am getting at just not as severe as what I experienced.

 

[polemite.productions]

i recently realized that i don't think i've ever changed out the spring in the secondary. it's likely due. stock 2012 secondary. it is a black/blue stripe spring, with what appears to be a 36 degree helix, based on the part number.
should i just replace the spring as is, and be done, or was there ever a consensus about a different helix/spring combo that is better?

 

[spoon]

That is all the stock parts for high altitude, check your rollers for seizing/cracking, spring might be getting weak if high miles, check helix ramps for wear from rollers at start of shift, been known to get wear that acts like a notch causing shift issues.