nytro stumble

[wyoyami80]

so I need a bit of input from the pro's. I have a new to me 08 nytro. took her out for the first time yesterday. I noticed the engine has a bit of hesitation when I stab the throttle. can anyone give me an explanation if this is normal. I traded up from a 98 MM700, so maybe the nytro response isn't going to be the same. Also, the engine changes pitch when riding on the trail. almost as though it switches into an idle mode. I know my explanation is confusing. I installed copper exhaust gaskets and ran the exhaust under the tunnel. being my first ride on the nytro, i'm probably being a bit over critical.

overall, I would have to say the nytro is very different from the MM. it will take me a bit to master the new sled. all the info from here has been very helpful.

thanks

 

[gc_srt]

Hesitation is not normal, what rpm is this happening at? I would try adding sea foam to the fuel as it sounds like an injector problem.

Nytro is a completely different sled than the MM. I went from a XTC to an XTX and it takes some time to get used to it. Nytro is quite top heavy and is harder to throw around unlike the Vmax chasis.

Are you getting an engine code with the pitch? Is it going into limp mode?

 

[wyoyami80]

The hesitation is around 4500-5000, but only a split second. It was doing it again last Saturday. A friend explained the pitch change as a load/non-load sound. Would there be a warning light indicating a code? I will have to try sea foam. Not sure how long the sled sat before I got my hands on it.
thanks for the tips.

 

[gc_srt]

If is was a tors code (code 84), it would go completely into limp mode and then fire back to life. It would be less of a hesitation and more falling on its face.

I would try looking at fuel issues first.

 

[wyoyami80]

This is definitely more of a hesitation. Is there an OBDII port or something I'm missing to check codes?
I did notice more response above 5500rpm. I only run 91 octane.

 

[moab11]

no need for 91 fuel, these just require 87. 91 won't hurt, just spending unnecessary money. I would bet on a fuel quality issue, or something with the exhaust is causing the hesitation, possibly causing the fuel map to lean out at certain points.

 

[wyoyami80]

Ya know, I completely forgot to mention the exhaust. I changed it to under-tunnel using a $30 muffler from O'Reilly's. Didn't think the 4stroke would be that sensitive to back pressure / flow from the exhaust.

 

[steiner]

Ya know, I completely forgot to mention the exhaust. I changed it to under-tunnel using a $30 muffler from O'Reilly's. Didn't think the 4stroke would be that sensitive to back pressure / flow from the exhaust.

You may have found the problem right there. Yes, even 4 stroke motors can be fussy on the back pressure. The less back pressure the better the engine breathes at high output and rpm but then suffers at low and mid rpm and output.

 

[wyoyami80]

I was a bit afraid of that. Anybody know if re-mapping the fuel injection could help? I got pretty good at changing jets and metering rods. Now, I'm kinda lost. Tonight I'm adding an elbow to kick the exhaust out through the right side of the tunnel. The under tunnel drone killed my head. Thanks for all the input.

 

[NOS-PRO]

I changed my exhaust on my nytro and experienced the same stumble. I put the stock exhaust back on and haven't had any problems. Haven't tried any mapping or fuel controller....just was happy with it stock.

 

[nitris223]

I think the hesitation is there with the stock exhaust but it seems to be more pronounced with a aftermarket exhaust. I think it is something to do with the engine breaking. I have a full Hindle exhaust and get a slight hesitation at the 5000 rpm mark. With a PCV and auto tune you can tune it out somewhat , some guys can get rid of it all together and the next guy can't.

 

[nate007]

nitris223 is correct, and the stock sled exhaust does muffle the sound enough that people don't notice it. It's still there, just not heard.
Aftermarket exhaust will definitely make it more pronounced, but it is normal as long as it's just a little bit if a burble when changing throttle positions rapidly.
AS long as it's a quick sputter and then it's back to business, I wouldn't worry about it.
the efi system on powersports stuff isn't as sophistocated as cars, and it's just not able to react as fast to rapid throttle/load changes. the 3 cyl motors are more pronounced due to their 120 degree firing order, but not an issue to worry about.

 

[mnmt_c08]

hey, I'm a new member and to leach on to this post (why i'm here at TY) I'm experiencing the same thing, on my 2010 mtx. I have a mcxpress turbo system. a stumble or burble when i stab the throttle. I sent computers off and everything. still no luck.... am i going crazy?? going to check the fuel injectors, see if they are leaking this weekend, but not to sure on where to go with it all....

 

[nate007]

Is yours more of an audible nose, or are you able to feel it too? Occasionally you can tune it out a little with a fuel tuner (or CO settings for lower rpm stumble), but is a common issue with a 3 cyl.

 

[mnmt_c08]

Is yours more of an audible nose, or are you able to feel it too? Occasionally you can tune it out a little with a fuel tuner (or CO settings for lower rpm stumble), but is a common issue with a 3 cyl.

You can definitely hear it and feel it. been doing a little more research. I'm thinking I have a dripping injector in the turbo set up. I know there always will be that little burble with the 3cyl. set up, but its a little more there than a person wants.