Idle varying up and down by 500 rpm on 09' TM8?

[Dogmeat]

Ok, I this sled never used to do this, but what happened is I was riding last week in some really deep powder, I hit 1350 on my EGTS during tractoring through it, and somehow the sled died, which I had thought was perhaps due to lack of air.

Come to find out, the 1/8" poly line that supplies boost pressure to my EBC and fuel pump as part of the BD kit had apparently gotten too close to my pipe and had a hole melted in it.

I replaced the poly line this evening, routed it and tied it down so its moore away from the pipe and added more rubber tubing insulator, etc...

I have not yet actually ridden the sled again under boost.

But what the sled is doing, even after warming up for 10 minutes, is varying the idle by like 500 rpm. When I first start it up from cold, it will go from 2100-2200 rpm like it always did back down to around 1800, but then after about 10 seconds it comes right back up to 21/2200 rpm ... stays there for 20 seconds or so, then goes back down to lik 1600 or so .... then right back up to 2200 ... if I blurb the throttle, it settles down to 15-1600, but then after about 5 seconds its back up to 2200 rpm ...

Any ideas on what could possibly be causing this? It never used to do this even after the first couple rides on the turbo, so I'm really kinda confused as to what changed.....

Any help appreciated, thanks.

 

[Dogmeat]

Anyone got any ideas?

 

[WyoBoy1000]

I would start by looking at pistons and cylinders through the y-pipe and a compression test, not because of idle issues but because you got it that hot and it died. That is a very tell tell sign of scuffed pistons. If your boost line had a whole in it then the ebc wont supply enough fuel because it didn't think there was as much boost. Sound like a lean scuff. I hope not for your sake, but what where you thinking letting it get that hot, thats about 100* hotter than anyone recommends.

 

[Dogmeat]

I would start by looking at pistons and cylinders through the y-pipe and a compression test, not because of idle issues but because you got it that hot and it died. That is a very tell tell sign of scuffed pistons. If your boost line had a whole in it then the ebc wont supply enough fuel because it didn't think there was as much boost. Sound like a lean scuff. I hope not for your sake, but what where you thinking letting it get that hot, thats about 100* hotter than anyone recommends.

Too much snow, couldn't see the EGT gages. It hadn't ever gotten that hot on me before.

 

[WyoBoy1000]

So it read that when you used the recall, got it. Give it a look and let us know, you might have got away with it, I did once. Sometimes when they hit temps like that it can set limp modes and I've even had it take out the pipe sensor.???

 

[sledstew]

Ive seen EFI sleds surge like that when they have an air leak between the throttle bodies and the reed cage.

 

[Dr. Shokula]

Surging at idle or rough idle usually spells vacuum leak. Listen for a hissing sound or spray parts cleaner or ether around the hoses, the sled will rev up a bunch when the parts cleaner gets sucked through the leak. Easy way to pinpoint the general area of the leak.

 

[Dogmeat]

Welp, the problem was twofold ..

Fixing that poly line obviouly made the boost / egt / duty cycle all of that work the way its supposed to, but the other issue I had with the idle was the POS goldfinger left handed throttle not allowing the throttle to seat properly

yanked it, the sled is now idling at 1800 rpm +/- 100 rpm or so instead of +/- 500 pm.

Had it out at strawberry yesterday and it ran awsome .... 8.5 psi, %97 duty cycle, after a 30-45 seconds pulls WFO my EGT's were between 1200-1220 ...

I think I'm done messing with it now

Boost is cooooooooool..

cept now I just want more of it

 

[WyoBoy1000]

thanks for the update, i hate lefty Throttles for that exact reason