08 mcx sent this email off to mcx see what happens.
End of last season I started having some unusual problems. Sled currently has 8000km on it and has basically run flawless since the day I purchased it. I have been through this kit/sled numerous times on basic maintenance so I am very familiar with the set up. Here is the story and hopefully you can give me some feedback or what to look for.
One day while riding deep snow at elevation all of a sudden I was losing boost pressure…..it would build boost for about 2 seconds then dump all the pressure. First off I was thinking the charge tube must be off, checked it it was fine, intercooler was tight, all charge tube side looked good. Then started going through the basics, charge side, everything looked good, exhaust side no leaks. Bov was functioning correctly. Check wire connections everything seemed to be ok. Finally stumbled upon the control wire that runs from the mcx box back to the altitude sensor deal back near my air intake, it had rubbed through and I think was messing with the sensor causing it to dump boost? Not sure if that is a safety setup that if the sensor does not read correctly it dumps boost? Anyway patched it up and seemed to run better. Later that night I patched in a new piece of wire. Next day it seemed like I was building boost and not much trouble.
The next weekend I go out and intermittently it started doing the same thing. This time it would allow me to build boost and run for 3-4 seconds…….then dump boost ………..then build boost again. It did not seem to matter if I gave it full throttle or came on nice and smooth it would eventually loose boost pressure then build back up again. This seems to happen more often under heavier load like climbing a longer hill. It will be pulling very hard and drop pressure so quickly that some times I almost go forward over the bars. I checked very closely and it was not hitting the rev limiter but that is sort of what it felt like just more dramatic/severe.
I do have a datalogger hooked up but did not do any datalogging when this was happening as it was the last day/trip of the year.
Again just wondering what your thoughts are? Could the alt/temp sensor on rear be malfunctioning?
In the next 2 weeks I plan to do a minor breakdown/runthrough of entire sled just not sure what I am looking for that could be causing this.
It has a new fuel pump on it (external fuel pump), maybe 500km on it. I will replace the fuel filter as well.
Wondering if maybe the injectors where not firing fuel for some reason? Any reason the injectors would be failing.
It was like I was loosing fuel, injector spray, dumping boost, hitting rev limiter sensation.
Cruising at low speeds low to mid throttle it never seems to happen more at ¾ to full with load……ie. Climbing or very deep snow.
I have had exhaust leaks, bellow leaks, exhaust gasket leaks, plugged fuel filter before but this is acting different then any of those conditions.
I will be climbing away building boost running smootly and then sputter sputter sputter……then back to building boost.
I understand it can be numerous items just curious at what your thoughts are. If it happens again I will definitely do some data logging to help diagnosis the issue.
End of last season I started having some unusual problems. Sled currently has 8000km on it and has basically run flawless since the day I purchased it. I have been through this kit/sled numerous times on basic maintenance so I am very familiar with the set up. Here is the story and hopefully you can give me some feedback or what to look for.
One day while riding deep snow at elevation all of a sudden I was losing boost pressure…..it would build boost for about 2 seconds then dump all the pressure. First off I was thinking the charge tube must be off, checked it it was fine, intercooler was tight, all charge tube side looked good. Then started going through the basics, charge side, everything looked good, exhaust side no leaks. Bov was functioning correctly. Check wire connections everything seemed to be ok. Finally stumbled upon the control wire that runs from the mcx box back to the altitude sensor deal back near my air intake, it had rubbed through and I think was messing with the sensor causing it to dump boost? Not sure if that is a safety setup that if the sensor does not read correctly it dumps boost? Anyway patched it up and seemed to run better. Later that night I patched in a new piece of wire. Next day it seemed like I was building boost and not much trouble.
The next weekend I go out and intermittently it started doing the same thing. This time it would allow me to build boost and run for 3-4 seconds…….then dump boost ………..then build boost again. It did not seem to matter if I gave it full throttle or came on nice and smooth it would eventually loose boost pressure then build back up again. This seems to happen more often under heavier load like climbing a longer hill. It will be pulling very hard and drop pressure so quickly that some times I almost go forward over the bars. I checked very closely and it was not hitting the rev limiter but that is sort of what it felt like just more dramatic/severe.
I do have a datalogger hooked up but did not do any datalogging when this was happening as it was the last day/trip of the year.
Again just wondering what your thoughts are? Could the alt/temp sensor on rear be malfunctioning?
In the next 2 weeks I plan to do a minor breakdown/runthrough of entire sled just not sure what I am looking for that could be causing this.
It has a new fuel pump on it (external fuel pump), maybe 500km on it. I will replace the fuel filter as well.
Wondering if maybe the injectors where not firing fuel for some reason? Any reason the injectors would be failing.
It was like I was loosing fuel, injector spray, dumping boost, hitting rev limiter sensation.
Cruising at low speeds low to mid throttle it never seems to happen more at ¾ to full with load……ie. Climbing or very deep snow.
I have had exhaust leaks, bellow leaks, exhaust gasket leaks, plugged fuel filter before but this is acting different then any of those conditions.
I will be climbing away building boost running smootly and then sputter sputter sputter……then back to building boost.
I understand it can be numerous items just curious at what your thoughts are. If it happens again I will definitely do some data logging to help diagnosis the issue.