Impulse Nytro low speed stumble

[XtremeSpeedShop]

99% of all turbo problems I run into are related to fuel pressure, boost leaks or vacuum lines not routed correctly. It only takes one wrong tee or loose hose to ruin the whole system.

We run big injectors, heads, porting, Q16 fuel, E85, sea level, 10k, sand , snow, morning , night lol Are stuff runs just fine at idle and transition onto boost. Anyone that says big injectors cant idle or work simply dont have it set up correctly.

I would start from the beginning and double check wire connection,updated ecu, vacuum lines, boost leaks, fuel pressure, throttle safety switches, timing etc

 

[carlnytro]

How might a guy adjust low idle to get it from 1550 RPM to about 1700 RPM when engine is warmed up. My impulse system stumbles at this low RPM. Noticed if setting was at 1700 RPM to 1800 Rpm upon full throttle no hesitation. I believe Paul at impulse recommends this setting. Everything else is plumbed correctly, fuel pressure correct, plugs gapped correctly. I run the big injectors. I found how to adjust free-play in book but no low idle adjustment, thanks for help

 

[Iceman56]

I hear ya my PL with the big injectors was the worst running sled I ever had most stock 800's could give me a run at the time. Double and triple check exhaust as it has also been my nemisis. I had Dave at (Redline) do my header and combined with the boost it kit, my PL nytro is now the hardest pulling sled i've ever had it compares to my old MCXpress Apex. Here is the link to the boost it boys site Neil is one of the best i've delt with in the industry as hes a rider too and uses his own product. http://boost-it.ca/

It's not that it doesn't have power, it has insane power when you nail it. I love the power and everything else about it except the low speed stumble I have

 

[b_sandgren]

Yes you want to bumb your idle up to about 1800 rpm at idle. You have to pull the intercoller to get to it. It is a small Allen head with a nut on it by the throttle cable. Give your sled atleast ten minutes of idling to hit full operating temp before you set it. This helps with the low rpm stumble.

 

[carlnytro]

All I see is a phillips head screw and before your post came up I adjusted this screw out 1 turn. Seemed to bring idle up but a little erratic. Should I put this srew back in its original position and go for the allen screw. Or do both accomplish the same objective. Do you have to pull any other components out of the way to get to this allen screw. Which way to turn for more idle counterclockwise or clockwise.

 

[Motleyone]

Put the screw back to its normal position. The Allen head screw is tiny. It sits right beside the intake of cylinder #1, you loosen the lock nut first then screw the allen screw in about 1/2 a turn, then tighten the lock nut. The intercooler has to be off. Run it at 1700-1800 rpms. It is a mechanical adjustment that simply puts more tension on your throttle cable. Do not attempt to do this with the free play adjuster up by your handlebars or on the back side of the throttle body, it will mess with your TORS.

All I see is a phillips head screw and before your post came up I adjusted this screw out 1 turn. Seemed to bring idle up but a little erratic. Should I put this srew back in its original position and go for the allen screw. Or do both accomplish the same objective. Do you have to pull any other components out of the way to get to this allen screw. Which way to turn for more idle counterclockwise or clockwise.

 

[carlnytro]

Got it, thinks for the help. What is the phillips adjustment for? It did seem to adjust up the idle. I did put it back where it belongs and adjusted the allen screw to get 1750 RPM'S.

 

[XtremeSpeedShop]

The Phillips screw syncs the throttle bodies. If you have messed with it I suggest taking off the intercooler and making sure you get them sync back to where they should be. It can raise the idle but it wont for all 3 throttle bodies and will make it run really bad off the bottom.

Also you can call Paul@impulse or me to run the serial number on your box to make it has the latest update, some older boxes had a problem with low end.

Willie

 

[pf mod]

Who all has the low speed stumble on the there Impulse Nytro? Mine acts like it's loading up all the time when going slow through the trees, I can never hold the throttle in one place without it loading up and dying. I continuously have to blip the throttle to keep it going, it gets annoying.

Any you experts seen this problem? Anyone have the fix for this? I know I am not the only one, I have heard other people complain about it and my cousins Impulse Nytro that is identical to mine has the same problem maybe even worse. I have played with the fuel pressure before with not much help. I had the same problem before I had the closed loop system and same with it.

Any help would be appreciated, thanks

HI.
My nytro impulse was just as yours, but i think its gone now, it is not much snow here in Norway jet so i have not got to test it fully yet.
Mine is a 2011 and i talk to paul last spring, just when he drop`t the new program, here is what he told me :

Our new programming has a TPS table overlayed with the boost table and it is working very well from 3000-11000’. I haven’t tested it any lower. This tune gets rid of the stumble that some sleds seem to have that others don’t, I am not sure why this is. This tune also runs a little leaner cruise 13.0AF and little leaner top end 12.2AF for better fuel economy. [/COLOR]

I strongly adwise you to contact paul if you have any issue with your kit, Hi is werry helpfull and respond wery fast.

 

[raggededge]

I just got done installing the impulse kit on my nytro it did have a low speed stumble when i first rode it, I adjusted the fuel pressure a little at a time and within 30 min it went away and now it is awesome no lag no stumble just clean from down low all the way to top. The low speed stumble is not the impulse fuel system you must have something hooked up wrong or fuel pressure not set right.

 

[Linc]

Iceman, i've been searching for this same issue on an MCX, finally gave up looking for the tricky reason and went back to basics, I did a compression test, found the problem, actually a couple of problems, first problem was the valves were leaking, and no. 2 cyl was way down in comp, did a leak down and it was blowing through into the base, pulled it apart and found a seized ring. Try a comp test first, just to eliminate those issues. I didn't expect to find this, the sled doesn't have that many miles, but sometimes going back to basics is necessary.

 

[Iceman56]

Iceman, i've been searching for this same issue on an MCX, finally gave up looking for the tricky reason and went back to basics, I did a compression test, found the problem, actually a couple of problems, first problem was the valves were leaking, and no. 2 cyl was way down in comp, did a leak down and it was blowing through into the base, pulled it apart and found a seized ring. Try a comp test first, just to eliminate those issues. I didn't expect to find this, the sled doesn't have that many miles, but sometimes going back to basics is necessary.

Ouch that not good news... Hope mine isn't serious, I am sure it's something small and stupid that's easy to fix

 

[Linc]

It's pretty easy to check, then you can eliminate it as a problem

 

[yamiman]

I have the closed loop system and had problems just like yours. I called paul and now have it running perfect. I almost went to the boost it system but now theres no need. heres what ive done:

make sure the tps is grounded to battery
make sure map sensor is tee'd in between the stock map sensor and 4 way tee
I checked my throttle body sync and it was waaaay off
adjust your fuel pressure little by little, takes time but worth it
idle needs to be bumped up to 1800, think i have mine at 1850 or so

hope this helps some

 

[Longhorse]

I have the closed loop system and had problems just like yours. I called paul and now have it running perfect. I almost went to the boost it system but now theres no need. heres what ive done:

make sure the tps is grounded to battery
make sure map sensor is tee'd in between the stock map sensor and 4 way tee
I checked my throttle body sync and it was waaaay off
adjust your fuel pressure little by little, takes time but worth it
idle needs to be bumped up to 1800, think i have mine at 1850 or so

hope this helps some

I've been chasing the same problem for a couple years now, but I believe mine was fuel related, I used to run strait 110 because I do not run a head shim. When I started adding 50% pump premium the stumble seemed to go away.

 

[Linc]

And if that doesn't work, check your comp.

 

[constech]

Low end stumble

Mack at MPI told me the problem is related to the accelerator pump. He had me adjust mode 5 on my fuel injection controller all the way up and mode 6 all the way down. It is not completely gone but tons better, it is almost unnoticeable most of the time.

 

[Iceman56]

Problem Solved

Talked to Paul he said he's been chasing this problem that some Nytros have and found the fix.

With the latest flash and the closed loop the sled ran absolutely flawless on bottom end and low speeds. I could not even get the motor to hiccup once the whole trip, and I was trying.
I had the closed loop but not the latest ecm tunning, so if yours is still doing it after the closed loop get the updated flash.

Good job Paul! Should have just done this to start with

 

[big_red1a]

X2 new map is by far the best! Think it uses tps as well for mapping seems to help

 

[relentless rider]

Do all three map sensors need to have a vacuum line?, im hsve n idie problems as well on an 08 impulse nytro,