need help trouble shooting a 2011 nytro 240 mcx turbo

[stadey11]

symptom:
very lean and popping at 4-6psi boost when full throttle. engine needs to have load. does not seem to do it when riding on hard pack will go right up to 10psi boost. when in deep snow it goes lean.

history:
bought the sled just over a year ago. rode it twice worked great did not seem to have any boost issues. ran around 11-12psi boost.
rolled it down the mountain and when the tether pulled it did not work and engine was reving up while rolling and oil blew out. not cool. towed out to truck and next ride no boost. turbo seized and broke the shaft.
installed new turbo and have had above symptom ever since.

what has been found/done since:
fixed all boost leaks on intake, including all vacumm lines, blow off valve, takes presure 10-15psi, slowly bleeds down but will hold 5psi
does not have exhaust leak, stalls instanly when pipe covered

at an idle 4psi vacuum on gauge

tested secondary injectors found 2 not firing. replaced with new/different injectors and remapped mcx box
all fire from 4-30psi
replaced stock fuel pump with an external pump/regulator have fuel pressure 44psi at and idle and 50 or more around 6500 rpm

found wastegate actuator was leaking and replaced with new

new turbo control valve

replaced mcx wiring harness

also have rebuilt the motor, crank bearings were hot a time or two and coating between shim and crank was peeling/gone in a couple of spots. It had a couple of questionable valves and vale seals, but still seemed to run pervioulsy just fine (sled has 5300km on it before i bought it)

have tested the stator, resitances are all the same .2-.3 ohms, at an idle charging battery at 13.9v, same at high rpm.

I have an '08 stock nytro swapped out ECU's no difference in either sled

I have a friend with a 2010 nytro identical to mine on 310hp, tried his mcx box on my sled No change!

The snow is melting and this is the second spring I've been missin out on some great BC riding!!!

Any ideas are very welcome. Also I have a few very knowlegable people trying to solve this they are all stumped so far from shops who build these to back yard builders who have built a couple of there own that run awesome.

 

[Stigapex]

Had a simular problem in my Apex. Problem was: throttles came a little out under boost.


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[kviper]

Are you sure your not hitting rev limiter? That will show lean AFR's, boost #'s will jump all over and rpm will show low because the tac doesn't keep up. That would explain why it don't do it under more load.

 

[stadey11]

Are you sure your not hitting rev limiter? That will show lean AFR's, boost #'s will jump all over and rpm will show low because the tac doesn't keep up. That would explain why it don't do it under more load.

that has been considered, but it never did before the turbo seized up. Nothing should have changed clutch wise. I have never seen over 8800 on the tach. i know my stock hits the rev limiter around 92-9400 when it spins, usually on harder surfaces not in the snow. but you are right it does act very similar to that.

 

[kviper]

That's about the RPM you will see when you hit the limiter hard. Would be worth a try to add some weight and pull it harder. Maybe new Turbo is making more power from wast gate setting or something? Or just turn the boost down and see if it clears up that way you can make sure your not over boosting!

 

[stadey11]

I tried heavier weights tonight with out any luck. went 5 grams heavier with a significantly more heel weight.
I have pressurized the intake up to 15-20 psi and no apparent leaks so would have to think the throttles are not seperating, but that would definitly cause it to not fuel.
when I first was testing I only had 7-8psi boost and have since turned it up to 10psi

 

[Stigapex]

Somehow it seems like its running out of fuel. Have you checked the fuel line, from bottom of tank and back. Are the fuel running through the regulator in straight direction


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[Stigapex]

Have you removed the orginal pump. Is the external pump placed under fuel-level.
The fuelregulator is regulated with boost. 44 psi fuelpressure at idle with 4 psi vacuum is 48 psi at 0 psi and 58psi at 10 psi boost.

At 6500 rpm you should have at least 10 psi boost. Fuelpressure should be 58 psi


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[Stigapex]

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[kviper]

Being that it ran fine before and runs fine on hard pack under better load I would keep turning boost down till it clears up and then start going back up while watching gauges closely to see if it's starting to go lean. You don't want to stay at high boost if it is indeed running lean! What was RPM at lower boost? If you were set up for 10lb and you are still lean at 7 then as Stigapex said you could very well have a shortage of fuel (bad regulator or pump)! If it was me I would turn boost down as low as you can and see what response you get. Not sure what you mean by throttles not separating?

 

[stadey11]

The old pump has been removed and upgraded to the kit shown above. all fuel lines/filters are new.
the throttle comment was just a reply from a comment above. I was assuming that he meant that under boost the pressure would push the throttle bodies off the intake. Since I have no leaks I would think that the clamps are tight.

After some more digging I am leaning on fuel mapping of my controller being incorrect after I put the new injectors in the secondary fuel rail. My friends Turbo has the original injectors in his sled from MCX and I have changed mine and had it remapped, but I am thinking that the mapping was not changed. my Understanding is that the MCX (black injectors are larger than the ones that I have installed. Unfortunately I do not have the black injectors readily available to switch back to try this theory.

 

[Stigapex]

Then you must remap. I assume you have mcx gen 5. Megatune is the software. Send a mail to mcx, I'm sure they send you the program.


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[Stigapex]

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[kviper]

That's the only thing I don't like about my MCX, to much Fing around to tune! The Nytro I just had built is using the Dobec gen 4+. You can't control timing with it but the new gen 4+ that's coming later in the year will be capable of timing control. Very simple to tune and controls from set AFR using an o2 censor so set it and forget it. The controls and AFR gauge is one unit. So far I like it!

 

[Stigapex]

I know there is an autotune available for mcx gen5, but I haven't tried it, so don't know how it works.
I bought a timing-controll from Ulmer. That works ok


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