2011 Nytro MCX 240 bog issue

[kimoajaj]

Hi guys!

A friend of mine just bought a 2011 Nytro XTX MCX 240, sled runs great and everything seems fine, but if you let the sled sit for 15-20 minutes and then fire it back up and take it for a rip, it bogs heavily when trying to build boost. It backfires and sputters really bad, but if you keep it away from the "build boost" area it runs fine with no bog or hesitation.

Weird thing is that if you ride it it carefully for 5-10minutes the problem suddenly goes away and you can ride like normal again.

When you park the sled and let it sit overnight and then fire it up it doesn't bog at all.

I`m kind of familiar with the Nytro, have mounted a couple of MCX 190 kits and rebuilt some engines but I`m kinda stuck here.

Could it be drowning in fuel?

I figure the stock injectors should be able to give it enough fuel not to suddenly bog down (if the issue is with the MCX injectors), or does the MCX box also control the fuel delivery from the stock jets?

I`m thinking it could be something with the MCX box, but why isn't the problem there all the time?

Could moisture/ice in the vacum hose that goes to the MCX box have something to do with this?

Just guessing.. .

Any opinions very appreciated!

Oh and happy new year folks!


Joakim

 

[BADSLED]

If it is the MCX fuel controller perhaps you may consider removing the box and bringing it inside to dry out if there is possibility of moisture. Make sure the box is correctly oriented with vacuum hose positioned on bottom of fuel controller. This will minimize any moisture buildup inside.

Other common problem is leaking header - I personally decided to go with a custom steel header with no doughnuts from Dave at Redline.

• Can you be more specific and describe at what RPM does the bog condition start at?
• Does the sled build full boost? How many PSI or Kpa are you seeing at WOT?

 

[kviper]

What does the AFR gauge (asuming you have one) read when bogging?

 

[Stigapex]

I have the same problem with a Apex mcx290. I assume its something with the fuel delivery. My engine is newbuild after a breakdown. First I changed the map to give it more fuel but it didnt help, maybe it could be the mcx box. But I don't have any extra injectors like the nytro mcx240.

Anyway, in the moment a sled is starting to build boost it need alot more fuel.
The stock injectors in your Nytro would not deliver enough fuel. For me it seems like the mcx injectors aren't working, when this happens