My nytro lemon.

[DigDoug]

I swear my 2008 nytro mcx 270 is a lemon. Bought it used a month ago. Ride attempt 1 random dying - bad oil pressure sensor.
Ride attempt 2 my fueling computer fails.
Ride attempt 3 $900 spent on computer and I blow a fuel line off the fuel rail because a hose clamp was used in lieu of a proper factory fitting.
Ride attempt 4 installed proper fuel connector and I'm finally ready to enjoy my sled and now I notice it has a really random misfire. Tends to be at the bottom to mid throttle range, and mostly when im trying to hold a constant speed or constant throttle position. Usually as soon as I hit the accelerator it'll miss. The sled is still rideable, but it is super annoying, especially trying to hold a slower speed like going through town. I have to vary the throttle constantly. Under boost it seems to go away. Sometimes it's a burble, other times a pop like a light backfire.
This one has me stumped. I've tried:
-Replaced injectors with good ones
-Synced throttle bodies
-TORS was disconnected when I got it
-throttle cable is adjusted to spec
-coils tested good
-flex pipes and donuts good. (One cracked flex pipe when I bought it. Replaced right away)
-CO was already set at -15
-spark plugs brand new and gapped properly
-TPS checks out
-compression is good 135 cold 155 op temp
I've been chasing this for over a week so I'm sure there are things I tried that I forgot to list. I only have 50 miles on it since I've bought it and it is an amazing machine, but I'd really like to solve this issue. Any help greatly appreciated!!!

 

[Deeppow16]

All nytros make a noise that sounds like a back fire at low to mid range and it makes the noise when you give it gas. The only time you hear it is when you have a performance exhaust on it or in your case a turbo. There is no fix for it as far as I know. Anyone who has owned a nytro on this site will tell you the same thing. I'm not saying this is your problem but it sounds just like what I dealt with on mine.

 

[AftonJay]

Yeah, my stock XTX makes a similar noise (from your description) but never seem to affect it.

 

[DigDoug]

This is more than just a noise, the sled falls on its face sometimes. Sometimes it will completely miss on one cylinder for a few strokes then go back to firing again. It is not just a byproduct of the turbo setup. All these MCX turbos will hiccup when you punch the throttle. My friend has the exact same machine set up identical to mine, and his doesn't have any of these issues. Under boost my sled runs great! Doesn't miss a beat. It's just the trail riding throttle range is where I'm having the issues that are driving me bananas.

 

[Mtnviper]

You might check your main wiring harness for chaffing/shorting to ground. One spot in particular that I remember causing an issue is the small "nub" on the front motor mount, that would wear into the harness and cause a short to ground. On my old Nytro, I cut it off with hacksaw blade and filed it smooth to prevent further damage.
There is a pic in the last post in this thread. https://ty4stroke.com/threads/wiring-harness-rub.131747/

 

[DigDoug]

I did check the common wire rub spot and it had been corrected, but I believe I have solved the problem!!!
I did three things:
1. removed the 3lb lithium battery and replaced with OEM.
2. My BOV had a small dent, which I was surprised to find out had jammed my BOV partly open, so I was leaking boost.
3. I inspected my starter relay, and sure enough, mine was full of corrosion. I cleaned it thoroughly (all nytro owners from 08 to 10 should inspect this part as it controls your fuel injection) and it will be replaced by an updated version during the summer.
I went for a ride and no more stumble! Only problem is now I'm making 20 psi and overboosting. Good ole nytro lemon! At least it is an easy fix this time. Thank you for your input everyone!

 

[theCATman]

So.... you've bought a 12 year old Nytro with an aftermarket turbo, that sounds to me like was installed by the previous owner, who is a hack and should only be allowed to touch soft, blunt objects, and somehow it's Yamaha's fault that this sled is a "lemon"?

You can't be serious.

 

[DigDoug]

So.... you've bought a 12 year old Nytro with an aftermarket turbo, that sounds to me like was installed by the previous owner, who is a hack and should only be allowed to touch soft, blunt objects, and somehow it's Yamaha's fault that this sled is a "lemon"?

You can't be serious.

Don't get upset, the title of the thread is supposed to express exacerbation at a newly purchased sled that had a lot of problems (not mentioned by the p.o.), not be an insult to Yamaha. Yamaha builds a great product and I really have enjoyed this nytro despite the startup problems. As far as who installed the kit, well that was Mark Leipheimer, yes the owner of Mcexpress USA division, so the install was done right, it was the two hamfists who owned it after the intstall that created all the problems...

 

[Mountaintech]

Glad you solved it!