MOUNTAIN VMAX4
Pro
I have a 2008 Nytro MTX with a MBRP custom under tunnel that runs clear to the back of my sled and and exits right through where the snow flap rivets on.
I have been hearing a miss/sputtering sound at high rpms, I thought it was the rev limiter but it was not as I clutched the peak rpm down. I do not have any air or fuel mods to go with the exhaust. Usually when you improve the exhaust you should improve airflow as well. Sometime it seems that the problem is worse when wheelying. I checked for water in the tank and found some so I drained the tank and put fresh fuel in. I also found a loose exhaust clamp as well but these did not fix the issue. While I was out riding I found out that a rubber from my airbox to the throttle bodies was not pushed on correctly. I changed that while on the last ride but it did not fix the problem. I noticed that the clamps do not squeeze the rubbers to the throttle bodies very securely.
I am considering buying the Ulmer Racing Package with the air intake pods/exhaust header/spark plugs/power commander. I am hoping the ability to tune the fuel and extra air flow will help.
ANY IDEAS? Thanks, Justin
I have been hearing a miss/sputtering sound at high rpms, I thought it was the rev limiter but it was not as I clutched the peak rpm down. I do not have any air or fuel mods to go with the exhaust. Usually when you improve the exhaust you should improve airflow as well. Sometime it seems that the problem is worse when wheelying. I checked for water in the tank and found some so I drained the tank and put fresh fuel in. I also found a loose exhaust clamp as well but these did not fix the issue. While I was out riding I found out that a rubber from my airbox to the throttle bodies was not pushed on correctly. I changed that while on the last ride but it did not fix the problem. I noticed that the clamps do not squeeze the rubbers to the throttle bodies very securely.
I am considering buying the Ulmer Racing Package with the air intake pods/exhaust header/spark plugs/power commander. I am hoping the ability to tune the fuel and extra air flow will help.
ANY IDEAS? Thanks, Justin
Has it always missed with the under tunnel exhaust or is this something new? Does it miss under full throttle or during on/off throttle situations? You want to make sure the connection between the airbox and throttle bodies are sealed good. Any codes?
APEX 06
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Maybe blockage when wheeling.
MOUNTAIN VMAX4
Pro
Airbox seal
I dont think the airbox seal is very good the allen clamps dont quite tighten up enough on mine.
I dont think the airbox seal is very good the allen clamps dont quite tighten up enough on mine.
They only will tighten so far and bottom out. Should be snug though.
With many different under tunnel set ups, header set ups even a broken header with just pipes into the tunnel. In every type of snow for 3k miles I have never had the engine not run good. I would look everywhere else before the exhaust.
Just my opinion.
Fuel flow issues? Screen on your fuel pump clogged?
All the issues with free flowing intake/exhaust are mid range in and out of the throttle misses so I wouldn't see it being a fuel mapping issue unless your computer is messed up. Air box I wouldn't see causing a problem either.
Just my opinion.
Fuel flow issues? Screen on your fuel pump clogged?
All the issues with free flowing intake/exhaust are mid range in and out of the throttle misses so I wouldn't see it being a fuel mapping issue unless your computer is messed up. Air box I wouldn't see causing a problem either.
sonds
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May need a fuel controller?
Off Trail Mike
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MOUNTAIN VMAX4
I tend to agree with Sonds.....fuel controller.
My guess is the MBRP exhaust has decreased your exhaust back pressure at high rpm which has leaned out your A/F mixture. You can appreciate that more restrictive mufflers tend to increase backpressure with rpm (exhaust flow). So at low rpm/throttle, the MBRP and stock yami may have similar backpressures, but as you increase rev's (thus exhaust gas flow) the difference between the two starts to widen quickly. Normally these differences are felt up in the high rev/throttle position
We are doing alot of work on tunnel dumps and aftermarket pipes, and we found the '08 and '09 models to be more sensitive to exhaust changes, but if your aftermarket exhaust is less restrictive, which most are, you will need a fuel controller to compensate. That is if you really want to get rid of the miss. Of course that also means you are making more horsepower upstairs. Won't be much, maybe 2 - 3hp, but better more than less.....
My 2 cents
OTM
I tend to agree with Sonds.....fuel controller.
My guess is the MBRP exhaust has decreased your exhaust back pressure at high rpm which has leaned out your A/F mixture. You can appreciate that more restrictive mufflers tend to increase backpressure with rpm (exhaust flow). So at low rpm/throttle, the MBRP and stock yami may have similar backpressures, but as you increase rev's (thus exhaust gas flow) the difference between the two starts to widen quickly. Normally these differences are felt up in the high rev/throttle position
We are doing alot of work on tunnel dumps and aftermarket pipes, and we found the '08 and '09 models to be more sensitive to exhaust changes, but if your aftermarket exhaust is less restrictive, which most are, you will need a fuel controller to compensate. That is if you really want to get rid of the miss. Of course that also means you are making more horsepower upstairs. Won't be much, maybe 2 - 3hp, but better more than less.....
My 2 cents
OTM
swelly
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Fuel controller, sounds like it is running lean to me.
Check, your throttle position sensor. Its very easy, I'm heading out riding right now so I can't look up the exact directions but basically in your diagnostic mode there will be one that changes as you depress your throttle. It should be around 6 with the throttle closed and 100 at wot. If it doesn't read all the way to 100 then your never getting full fuel.
Also check your foam in your air filter, I doubt it but a easy check.
Fuel controller will never hurt but you have a bigger problem than free flowing exhaust.
Also check your foam in your air filter, I doubt it but a easy check.
Fuel controller will never hurt but you have a bigger problem than free flowing exhaust.
Screen
I dont think it is the fuel screen on the fuel pump that is clogged because it is a big screen in the bottom of the tank. Just curious if there is another screen you are talking about? Other than the big one on the bottom of the fuel pickup for the pump that is a white filter that is about 3in by 5in long.
I may be able to get a computer from a friend with a Nytro to hook up and see if that is it.
I thought maybe I have a problem with one of my injectors or a dirty throttle body. I am thinking maybe I should pull my airbox and check the throttle bodies.
I will try and check the throttle position sensor but it was in spec last time I was trying to diagnose this. I think I just went on my last ride so I am just going to go through everyting this summer real good and hope to find the problem.
I dont think it is the fuel screen on the fuel pump that is clogged because it is a big screen in the bottom of the tank. Just curious if there is another screen you are talking about? Other than the big one on the bottom of the fuel pickup for the pump that is a white filter that is about 3in by 5in long.
I may be able to get a computer from a friend with a Nytro to hook up and see if that is it.
I thought maybe I have a problem with one of my injectors or a dirty throttle body. I am thinking maybe I should pull my airbox and check the throttle bodies.
I will try and check the throttle position sensor but it was in spec last time I was trying to diagnose this. I think I just went on my last ride so I am just going to go through everyting this summer real good and hope to find the problem.
MOUNTAIN VMAX4
Pro
Friends computer
I just posted from my friends computer that was me though!!
I just posted from my friends computer that was me though!!
MOUNTAIN VMAX4
Pro
PCV
OK the miss is still here it has never gone away and getting real tired of it but may be getting closer. I hate to get rid of it cause of the problem cause I am getting it setup to where I really like the power now with K&N filter kit and Power Commander 5.
I was thinking that it was fuel related before but lately I am thinking it is something else today the dash turned off then turned back on really fast today while I was testing it after adding weight after a ride I was thinking maybe my rpm was too high but that was not it.
A buddy recommended I check my tether/rollover valve as they had some issues with the ones Yamaha sold. So I am going to completely eliminate that off of my sled too see if that is the problem.
I had a boondocker fuel controller too and tried a lot of different settings but none fixed it then went to a PC5 from Ulmer and seemed to run better but problem was still there.
I would really like to fix this problem before the snow leaves so I can focus on other mods next year other than fixing this ongoing problem. Any other opinions on this would be appreciated, Thanks
OK the miss is still here it has never gone away and getting real tired of it but may be getting closer. I hate to get rid of it cause of the problem cause I am getting it setup to where I really like the power now with K&N filter kit and Power Commander 5.
I was thinking that it was fuel related before but lately I am thinking it is something else today the dash turned off then turned back on really fast today while I was testing it after adding weight after a ride I was thinking maybe my rpm was too high but that was not it.
A buddy recommended I check my tether/rollover valve as they had some issues with the ones Yamaha sold. So I am going to completely eliminate that off of my sled too see if that is the problem.
I had a boondocker fuel controller too and tried a lot of different settings but none fixed it then went to a PC5 from Ulmer and seemed to run better but problem was still there.
I would really like to fix this problem before the snow leaves so I can focus on other mods next year other than fixing this ongoing problem. Any other opinions on this would be appreciated, Thanks
YamahaRider10
Extreme
I had the same issues as well. I just replaced the relay on my Yamaha ROV with a lower amp relay and all my stumbles were gone. Mine was doing the exact same thing.
lund
Pro
I had the same issue 2 years ago, JUNKED the ROV and problem solved. There are way better ways to keep the oil in the engine and tank then the ROV.
