Please help

[athiel]

My nytro has a mcx 180 kit in it and while riding today it would bog down and the air fuel ratio went from 13-14 to 17 to where it wast reading at all, what could be the issue?

 

[Northernboy]

I'd start with the simple things, new plugs gapped 0.018 and check all electrical connections and maybe put dielectric grease in them. It would be good to check the fuel pump pressure too.
Also what is your boost pressure at when this happens? Is it stable?

 

[JP270NYTRO]

I'd start with the simple things, new plugs gapped 0.018 and check all electrical connections and maybe put dielectric grease in them. It would be good to check the fuel pump pressure too.
Also what is your boost pressure at when this happens? Is it stable?

x2 and maybe its your a/f sensor probe going bad.

 

[yukon yamaha]

How was your intake sock? Was it free of snow and ice build up?

 

[athiel]

I checked all of those and what after a couple calls we found that there wasnt enough vacuum. we checked the lines and found that the vacuum cap on the chaincase side cylinder had a hole in it so we fixed that but vacuum was still down. We then found that it is not getting fuel to that same cylinder. We dump fuel into where the plug goes and it sounds good until that fuel in used up. Could this be a plugged injector or something else?

 

[yukon yamaha]

hmmm maybe mcx brain box? not too often you see an injector go

 

[Northernboy]

You could remove the throttle body and measure how much each injector is delivering with a glass under the throttle body and going into diagnostics and firing each injector on at a time.

 

[athiel]

It could be the box but we think it might be the injector because it the first injector on the rail and the fuel is getting to the other two further down the rail. We are in the UP right now so be a couple of days before can get it tore apart to really check it out just trying to get some ideas on what it could be.

If it was the box any way to test that to see if its bad?

 

[rxrider]

Water in the gasoline plugging the fuel filter, it's possible.

From Your AFR Readings I'm pretty sure it's a fuel delivery issue.
If one injector stops fireing you will not get a lean condition, Your sled will continue to run on two cylinders, that one is very easy to spot. It's like when one plug goes it continues to run on the remaining cylinders. But it will not bog Down only run With a lot less Power.

My bet is lack of fuel entering the fuel rail, caused by obstruction in the fuel delivery or a failing fuel pump, causing a lean condition as see at the AFR meter. Below 15.5 AFR Your sled will not make any Power anymore. At 17 AFRs Your engine will stall.

 

[s1d3w1nd3r1480]

Well it always works to check the simple things. Sure enough it's the harness plugging into the ecu. Even though I checked and made sure it was clipped tight and not rubbed through while he long things up north I found in the shop wiggling the connector it would run fine and then drop the 3rd cylinder if it was wiggled just right. After an hour messing with it I cannot figure out which wire is causing this however I did get it zip tied together and is running great now.

Does anyone have a wiring diagram for the ecu plug so I can locate which wire is responsible for the injector on 3rd cylinder?