Just got home from a wicked 2 day trip, bottomless thick heavy pow in the loose trees and gently sloped pastures... the odd hillclimb. Avy conditions were bad so we stayed out of the high alpine and complex terrain. Today was probably the single most fun day I have had on a snowmobile!
Anyways, my run-ability issues have returned... but slightly different.
From 1/3 throttle and up, or with any sort of load on the track it ran awesome. Pulled hard all weekend between 7400 and 7650 depending on elevation. Great response, normal fuel economy, normal oil consumption, plugs are a bit rich looking compared to normal.
Idle is my biggest problem: After run time when stopping, the idle hangs at about 2000 and sounding like only 1 cylinder. Most of the time, after a moment it comes down to about 1300 or so and at this point it sounds like 1 cylinder is mis-firing sporadically... other times the idle remains at about 2000. Start up gives me the 1300 rough idle.
Off-idle to 1/4 throttle have a little bit of sputtering, hardly noticeable.
Coming out of WOT, if I ease off to about 1/4 and hold.... I occasionally find a flat spot... just sounds a little flat and sick. If I quickly go back to WOT from here it sometimes hangs at that RPM (about 6000) until I made another throttle correction. At any time during this if I make a small correction to the throttle it immediately comes back to life. This does not happen often at all, but is there.... sounds alot like the 5000 - 6000 rpm bog issue posted about frequently. This has happened in the past but rarely, starting to become less rare now.
I had adjusted my idle recently so it is probably not at .930 on the TPS anymore, I will re-test and set the TPS / idle when I get started on it.
Any thought on this? I'm expecting more wiring issues or a sensor glitch. Whats got me scratching my head is that it runs excellent at mid-to-high rpm, and what the hell would make it run on one cyl like it does at low rpm / less than 1/4 throttle.
Frustrating stuff at times this EFI stuff lol. So far my plan is to re-test / check all sensors, coils, reeds.. the usual. I made sure to get helmet cam footage / audio of these problems in action, I'll hack together a clip and post it here within the next few days. Back to work tomorrow night, this was my fifth weekend in a row out on a BC mountain trip, loving life!