BDF#900
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Sled quits after full throttle on a good uphill pull, starts right up again. Doesn't do it on flat pulls. Any ideas?
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Mcx 1200
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BDF#900
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full tank, seems to be altittude related
sirkdev
Active VIP Member
Fuel mixture? Do you have an afr? My old m8 used to do that all the time just randomly shut off. Or a problem with the mapping.
DRD
Active VIP Member
Fuel pump not keeping up? More load on a pull uphill and pushes it past it's limit.
turborev
Member
I am guessing that it is running rich on the top end. It will burn some of that fuel at WOT bit when u let off it can't. Up the trail it runs because of elevation. There is better air the lower u go.
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BDF#900
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Familiar with turbos, just wondering if anyone out there has had same problem with theirs. Does the MCX box have its own barametric sensor?
turborev
Member
Mine has done it a couple of times and that is what was wrong with mine. I am running a rapid bike controller. Just had to lean it down on the top end, it seems to be getting better. I don't want to take real big steps.
Stewd
Member
Had the same problem with mine, tried everything but turned out to be the fuel pickup in the tank. Change over to the XP pick up and problem will go away. Talk to the guys over at TSS and they can give you the part numbers required.Had the rapid bike fuel controller originally, changed over to Boost-it and a water to air intercooler and the sled flat out rips now and have had no issues in all conditions from climbing big chutes to 3' powder.
NM
Boost It - Fuel your Boost
I would guess the same as others have said. I think it's going rich on the top then bogging. The reason it is worse with elevation is that the turbo has to work harder to overcome the thin air and creates higher charge temps which creates a richer condition. Next time it does it, quickly put your hand on the charge tube and intercooler. I think you would be surprised at how hot they are.
It could also be the fuel pickup.
That is a big motor and they need a ton of air. Options are turning the boost down, getting a more efficient intercooler, or getting a bigger turbo.
It could also be the fuel pickup.
That is a big motor and they need a ton of air. Options are turning the boost down, getting a more efficient intercooler, or getting a bigger turbo.
backchannel
Member
Turbos usually run out of real estate quickly on flat ground so the shorter wot time may not show problems.
Looks like Neil covered it.
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BDF#900
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no shortage of real estate, 100mph lake runs for over a mile.
will check out the fuel pickup
it is a small turbo, and yes things are very hot in the charge tube dept
can a BOOST IT box be used as a replacement for the MCX, or is there other changes required? (injectors added/relocated)
NM
Boost It - Fuel your Boost
The Boost-It controller is a direct replacement for the mcx controller, and although you can trim the fuel out of the top end, it really can't fix the real issue.
We have had other mxc guys running our fueling on the mcx 1200s and the sleds ran great until in to a real hard long pull, and you could watch the 02 values drop as the intake air temps came up.
The reason it does not happen on a lake is because the elevation is lower and there is really no load on the motor even at wide open.
In my opinion a bigger turbo or a water to air intercooler is your best bet. Both would be best...then that thing would be a real rocket.
teeroy
Active VIP Member
is this dave's sled BDF? it quit on me on a flat run after chopping the throttle once, but it was on the clemina trail.
if the quitting thing was resolved, I'd sell my soul for that sled.....feels like an xp with the thrust of a pratt & whitney
if the quitting thing was resolved, I'd sell my soul for that sled.....feels like an xp with the thrust of a pratt & whitney
rob derkach
Active member
Chad from CR racing was having the same problem last year at yamafest. He was climbing the gash and twice he went backward Back down the shoot ?
teeroy
Active VIP Member
found this on dootalk, may have nothing to do with turbo. seems it's happening to stock 1200 sleds as well in need of help 1200 shutting off going down trail - REV-XR Chassis - 4 Stroke Performance and Trail Models - DOOTalk Forums
Stewd
Member
If your charge temperatures are high, chances are your intercooler is not adequate. I am running a powderlites stage 3 system, I had exactly the same problems on the stock kit. As mentioned earlier the fuel pick up was definitely a upgrade that was needed but I also had to upgrade to water-air, boost-it and a BRP front radiator kit (for spring riding cooling) to solve all the issues similar to what you are talking about. It is a bit of an investment but it took my sled from a frustrating and unreliable hill climber (as I never new for sure when it was going to cut-out on me) to one now that makes unbelievable power that I can rely on in any situation that i decide to put it in. As well as outperforming any of the turbo'd apex's or nytro's I have owned in the past.
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