Nytro with MCX 270 dies randomly

[DigDoug]

Hi everyone! I'm new to this forum and hoping to find some help. I just bought a 2008 nytro with an MCXpress 270hp kit that was installed around 1k miles ago. The sled will start and idle fine but cut as if the key has been turned off at almost any rpm above idle, but usually at 1/4 throttle or more. Sometimes I can get a few hundred feet and even build full boost, other times I'm barely moving and it dies. The cluster stays lit and no lights or error codes displayed, I have ruled out a bad tether, and the kill switch is disconnected and hard wired to the tether. I have replaced the ECU with a known good unit, and the wiring harness rub point spot is not an issue on this machine. It is definitely a loss of spark because the fuel injectors seem to keep firing causing it to load up and it is hard to restart (requires WOT to get it to sputter/start). Checked TORS and it must be disabled because I can't cause it to activate like I can on my other Yamahas, and the throttle cable appears to be in proper adjustment. Can anybody give me suggestions on what to check next?

 

[Mountaintech]

Wiring to oil pressure switch?

 

[DigDoug]

Wiring to oil pressure switch?

I'm going to dive into it tomorrow. Going to try swapping oil pressure sensor, crank position sensor, and if neither of those fix it, pickup coil. I'll also look at the wire routing to make sure nothing is pinched.

 

[DigDoug]

I'm going to dive into it tomorrow. Going to try swapping oil pressure sensor, crank position sensor, and if neither of those fix it, pickup coil. I'll also look at the wire routing to make sure nothing is pinched.

Ran the sled today for diagnosis and it only died once. That makes it difficult to swap sensors and look for a result. I unplugged and grounded the oil pressure sensor wire and the sled died in the exact same fashion as it was doing on the trail - no oil pressure light or anything. Is it normal for a nytro not to show a low pressure warning?? If I remember right my viper and phazers will both show an oil pressure warning.

 

[DigDoug]

Turned out to be a faulty oil pressure sensor. Now that I'm actually able to go more than a few hundred feet I'm noticing the sled seems to go lean and chatter/lose power, especially once boost is being built..sigh..on to the next problem...

 

[Mountaintech]

Well, one thing solved.