M7 dropping cylinder

[rigrat]

Good day. Hit a tree last season with my m7 which caused damage to my sleds hood, nose piece and other plastic plus the airbox was smashed.When the accident happened i was able to remove loose pieces and ride sled back to my pickup. The problem is that the sled started dropping a cylinder part of the time (may have inhaled some pine needles) into motor. I replaced all broken pieces and cleaned everything up. Took it for a rip down the ditch yesterday and found it was still dropping a cylinder. Sled seems to run ok at idle and part throttle but when opening it up to full throttle it will drop a cylinder everytime. It may not drop the cylinder instantly but will drop it very soon after WOT. If i go back to part throttle it will run on both cylinders again. Checked the compression and found both cylinders were within 5 lbs. One plug looked like it may have been fouling so i replaced it. No difference. If it was ignition it would probably run on one cylinder all the time, correct? Could it have a broken reed and would a broken reed cause it to act this way? Dealership mentioned unhooking kill switch, which i tried with no luck. Someone else mentioned checking ecu for code. How do i check for codes??Appreciate any and all help! Thanks in advance.

 

[rigrat]

ttt

 

[mtn mike on boost]

i would bet it all that you have a bad reed petal.
my m7 w/ a turbo did the exact same ting when i blew out a reed

 

[rigrat]

Thanks mike. I guess i will have to check the reeds but i will check fuel pressure and the sensor in the airbox first. If the reeds are ok is there any chance it could be an injector?

 

[mtn mike on boost]

again, id bet on a bad reed.i had an injector go out once, but its symptoms were totally different.id bet, you got some broken pieces of plastic in there, and thats what damaged the reed. keep in mind, if im right, and there is still a piece of plastic in there, be careful, it could stick your throttle body open...no fun

i wouldnt hesitate to check the reeds first.im almost positive

 

[rigrat]

Thanks again mike, will check reeds first!

 

[Vern]

if the reeds check out, take a look at the exauhst valves. last year my buddies m7 started running like you say yours is and it turned out one of his exhaust valve cables popped off of the servo motor. would run fine at idle and part throttle but when opened up only one valve was opening and it ran like crap.

 

[fixit]

EFI? barometric hose

Hey, is your M7 EFI? If so, be certain that the barometric hose (the clear hose that comes from the bottom side of the computer (CPU) isn't pinched or damaged from the crash. I've been working on a similar troubleshoot problem with a buddies sled and another snowest sledder had this suggestion. Good luck.

 

[rigrat]

Ok, i pulled the injection off and checked the reeds. I found a broken piece of the old airbox in the muffler side reed cage. Removed piece of plastic and reassembled. Took sled for a ride to find it will still drop a cylinder. If i start at an idle and go directly to WOT it will drop the cylinder. If i go from part throttle and slowly go to full throttle it will run ok part of the time. Part throttle performance seems ok. One thing i did notice is that the air box side of the injector bodies seemed quite oily. I double checked the sensor in the airbox and it looked ok. Clear hose from top of air box is ok. Again, it seemed to develop the problem after i hit the tree. Is there even a slight possibility that the impact could have caused the oiling system to push more oil to the engine??? If it was a cable off of the servo for the powervalves, would it not act up all of the time?

 

[tundramonkey]

Power valves don't open until around 7200. So when you pin it from the start the one valve may not be opening. That may also explain why it seems to run better at a lower rpm. Pull the cover off the servo and take a look at the cables and check the adjustment.

 

[Vern]

Power valves don't open until around 7200. So when you pin it from the start the one valve may not be opening. That may also explain why it seems to run better at a lower rpm. Pull the cover off the servo and take a look at the cables and check the adjustment.

yup, like i mentioned when my buddies sled popped a cable off it would run fine at idle and part throttle cuz both valves are closed but rap it up to where they're supposed to open and only one opened and it would run like crap.

 

[rigrat]

Pulled pipe, removed servo cover for powervalves. Cables are both in place and servo operates freely and i can look into y pipe and see powervalves moving up and down. Throttle position sensor was brought up? How would i check TPS? Should i raise rear of sled off of ground with servo cover removed to make sure servo actually works at rpm?

 

[Vern]

not sure on how to check the tps, but ya thats an easy way to see if the servo is working, well if it will rev up high enough for it to open.

 

[007]

Sounds like a ECU!

Did you run the sled with out the lights after you crashed?

A hard hit right by the ecu might be enough to jar it too.

That is what my sled acted like when my ecu shat out, ran great idle rippin around the yard slow soon as you got it around 6700 it would fall down and the temps would go cold.

KJP

 

[mtn mike on boost]

sorry, i would have thought for sure it was your reeds.
did you actually pull them from the case?they still sealed against the cage???
unfortunately you cant check the tps yourself, the dealer has the equipment for that.

good luck

 

[rigrat]

Damage to sled was not severe enough to effect the lights. Damage to the sled included the front bumper, skid plate, hood and airbox only. Hope it is not the ecu!! Still have to check fuel pressure but i have my doubts.

 

[rigrat]

Both reed cages were pulled from engine and the reeds appear to be in excellent shape. Is there any chance the efi could be overcompensating for lower elevation and extreme cold, causing one cylinder to run too rich? I noticed when me and my brother are riding our m 1000s at lower elevations and extreme cold that they seem to load up a lot more than usual. The temps had been about -30 celsius lately and makes road testing the M7 a freezing proposition!

 

[rigrat]

ttt

 

[007]

take a ecu off from a buddies sled and try it. if it works your know and it will take 2 mins to find out.

KJP