MCX Turbo Experts...Please Respond

[PUNISHER]

Background Info:
Have a MCX Nytro that I have 2 rides on now. First ride out, had a real bad fuel cutout problem. Thought it was the vaccum line off the bottom of the fuel pressure regulator being pinched against the frame. I rerouted some lines, and zip-tied in place.
Last week:
The sled would not engage weights in primary until manually moving sled and rotating track to have the weights engage under stock motor power (like 6500rpm engagement). All this after sticking it real bad and revving the motor/freespining the track. Took all the plastic off and noticed the vaccum line issue mentioned above. Pushed it around and loosened it up. Sled ran fine. Full boost and no rev-limiter slapping.

Todays issue:
Another good stick and a tad bit of revving/freespinning the track. Primary would not engage and not until, I put it in reverse and had the clutch engage around 4500. Just enough to unstick and then power forward, but same fuel cutout symptom. Sled ran tons better than last week, but was still cutting out and bouncing off the rev limiter when hitting higher boost levels. I would say about 75% better than last weeks problem.

My Question Finally:
Does the MCX box have a rev-limiter/load sensor on it to limit fuel if it feels no load after a free-spinning situation like mine for the last 2 weeks? If not, then any ideas on how to solve my problem? Outlaw motorsports (Dustin did the install for me) said possibly a bad Fuel Pressure Regulator last week, but said it wouldn't be intermittant. I need some serious help with this one.

Thanks in advance.
Tim

 

[snowy1]

I just got the first real ride on mine and everything works really good except between 3-5 lbs of boost it has a lean spot pops and spits and then pulls hard, my a/f readings are 11.5 to 12 befor and after this point but between 3-5 lbs they are 16,s, doesn,t sound like the same problem you are having, I will be calling my dealer monday to see what mcx can do to fix this, I have heard how this nytros with mcx are pulling the apex,s on the bottom but mine would not beat anything out of the hole due to the lean spot, doesn,t matter how I apply the trottle it pops and spits in this spot then clears out and runs great.

 

[summitboy]

Can you guys post a little more system info. What year sled and turbo kit. Who did the install ? All leads soldered ? Intake and exhaust sealed tight ? Good ground on fueling box ? Check for air leaks everywhere and make sure all wires and vac lines going to the right spots. What elevation and boost levels ?

 

[PUNISHER]

My system is a 08 Nytro with 08 MCX Kit. Installed by Outlaw Motorsports. Running at 5000 ft with 12 pounds (50/50 mix of 92 octane and 110 race fuel). I checked all the hoses after rerouting the fuel pressure regulator to make sure they all had good solid connections and no leaks at the nipples. Running a shockwave adjustable helix in the secondary and the primary weights are a little on the heavy side for 12 pounds, but want to be able to run 15 after figuring out this issue. If the ground wire goes to the negative battery terminal, than it is 100% connected. Took that off when rerouting everything.

Ran awesome all morning yesterday, until stopping at a warming hut. Started her up and went flying down the trail about 300 yards and left off quickly to stop for my group. From that moment forward it didn't want to run right. I would say it was running at about 75% capacity.

 

[snowy1]

2008 nytro mcx kit, installed myself. 10,000 ft. I have rechecked everything it is a good install, as I said sled runs great except from 3-5 lbs boost so its got to be in the mcx box, running 12 lbs just the way the kit came for now. wires all soldered, I have heard others say its common to have this lean spot but it appears mine is worse than others.

 

[Thistledoo]

Snowy have you played at all will the CO's?? Mine has got a tiny bop bop right off the bottom....but I mean tiny tiny. Have rode mine twice now and shes rockin....Just getting the chassis to work now waiting for the timber. Hows your timber workin?? Yours must be a bigger bog?? Like if I pin it from a stand still it will make 12lbs boost in like 6ft. We ride 7000 ft max though....maybe MC is still havin the high altitude problems??

 

[snowy1]

Snowy have you played at all will the CO's?? Mine has got a tiny bop bop right off the bottom....but I mean tiny tiny. Have rode mine twice now and shes rockin....Just getting the chassis to work now waiting for the timber. Hows your timber workin?? Yours must be a bigger bog?? Like if I pin it from a stand still it will make 12lbs boost in like 6ft. We ride 7000 ft max though....maybe MC is still havin the high altitude problems??

the timbersled is working great, no prob lem controlling transfere and rides great down the road, I haven,t played with the CO,s, mine is not a small stumple it pops and farts for acouple seconds, my trx would have killed this thing out of the hole, it doesn,t matter if I am at a dead stop or doing 20 mph when I hit the throttle it stumples and pops, then once it starts pulling it pulls hard, this is my first efi so I don,t really know where to start, atleast with a carburater I could dial it in. I bypassed the tors today just in case it was causing a problem but that didn,t seem to do anything.

 

[Ken Climb]

Most of the nytro mcx's have a slight "rich" burble there but nothing worth complaining about. Like Thistle said maybe it is a high altitude thing, cause all the mcx nutro's I've ridden with only ride around the 6,000' mark.

 

[Snoboner]

Mine is doing the same thing. Good a/f and goes real lean at low boost with spit n sputter. Takes off after it cleans out. Real irritating.

 

[Snoboner]

Ttt

 

[PwdrNut]

There should be a fix for this high altitude/low boost lean situation very soon.

 

[robertyoke]

2008 nytro mcx kit, installed myself. 10,000 ft. I have rechecked everything it is a good install, as I said sled runs great except from 3-5 lbs boost so its got to be in the mcx box, running 12 lbs just the way the kit came for now. wires all soldered, I have heard others say its common to have this lean spot but it appears mine is worse than others.

I bought my kit from high altitude boost (trey) in Salida co. I went riding with him this weekend in Crested Butte, his sled was way lean like yours. he has a new program to fatten it up through the low boost. Tried it on my sled and it would just blubber and surge at low boost. The a/f gauge almost never left the rch only to see 10.1 or so.(even lumping down the trail) had him change it back so I could ride the sled. His sled runs great with the new program and mine would not run at all.....go figure?? I think the boxes vary slightly from box to box and a one program for all will not be the answer.
All I can say is 16 lbs boost @ 11,000ft and bye bye rev boys! Even the superlight xp!
I let one guy hop on it and I rode his m8......I could not get my sled back! (and I could not get off that cat fast enough and back on my barking/whistle pig)
-robert

 

[SNOW JW]

You would think for 6k plus they would have this all figured out by now.