Odd 462 MT Problem

drf256 · Feb 18, 2020

FWIW,

This is the prototype of the front cover. It’s a @Red97 deflector on the inside. Finishing touches haven’t been made.

Joe may make up a kit for these limited room stainless cans. A block off plate can be easily added if one needed to go quieter for some reason.

Cobby08 · Feb 18, 2020

Mastermind said:
Piss off part timer.

Rep'd

MustangMike · Feb 18, 2020

I suppose, if all else fails, it could be just a traditional "when it gets hot air leak", but it seems more like a throttle problem.

Unfortunately, many times I have thought a problem was one thing, and it turned out to be something else.

Good luck with it Al, it seems to cut well!

~WBF · Feb 18, 2020

* Sounds like it has about three different symptoms going on with that thing.
It's running erratic from the get go and it was a lot worse at the end. It's surging at idle, The revs are fluctuating after it comes back down. It reminds me of taping of too much of
the starter cover with duct tape when needed to restrict the cold or power snow. Also swapping winter gates can do that if its not that cold. It's not something you often see? I don't no the saw but perhaps it makes the most sense it's from movement in the throttle plate, as said.
If it's fuel restricted and flutters down and starts to race then you won't have any way to manipulate that as you did by resting the teeth on the log. It's progressive. You can certainly manipulate a manifold leak or a faulty throttle that way, in cases.

I have some very primitive ways but the first thing I do is smack it hard with the heel of my right palm. (um..er...chainsaw that is.) You get used to running certain saws in all kinds of weather. Would work for a while with frozen 372 cable then you had to use deicer.

cus_deluxe · Feb 18, 2020

be real interesting to have this saw plugged in i think.

Billy Currie · Feb 18, 2020

How long has this saw been sitting at the dealer? Could the carb have any deposits from old fuel?

wcorey · Feb 18, 2020

That it comes down so consistently from racing to idle by touching the chain to wood would seem to eliminate a purely mechanical issue such as linkage or throttle plate.
Solenoid/coil would make sense to be the prime suspect...

EchoRomeoCharlie · Feb 18, 2020

wcorey said:
That it comes down so consistently from racing to idle by touching the chain to wood would seem to eliminate a purely mechanical issue such as linkage or throttle plate.
Solenoid/coil would make sense to be the prime suspect...

idk, the vibrations sent through the saw from hit hitting the wood could jostle a mechanical issue back to normal. Not saying that's the issue here, but I could see it.

Spladle160 · Feb 18, 2020

I just don't understand how it could be a solenoid coil issue. The electronics only control the fuel right? I don't think a saw could run that fast with a fully closed throttle plate and no air leaks.

Nutball · Feb 18, 2020

Spladle160 said:
I just don't understand how it could be a solenoid coil issue. The electronics only control the fuel right? I don't think a saw could run that fast with a fully closed throttle plate and no air leaks.

The throttle plate when closed still lets air through, just enough to let it idle, and to suck gas for idling. But it is idling very fast even for a lean idle, not that it isn't possible.

tree monkey · Feb 18, 2020

how much did you cut off the base? gasket or no?

Billy Currie · Feb 19, 2020

Sorry, after watching the video I would be leaning more towards a fuel tank vent than a stopped up carburetor.

Stump Shot · Feb 19, 2020

~WBF · Feb 19, 2020

Billy Currie said:
Sorry, after watching the video I would be leaning more towards a fuel tank vent than a stopped up carburetor.

Not typical of vent behaviour
That would be another progressive condition. Unfortunately you can't bring her back around with a 'spank bottom.

AKJonsereds · Feb 19, 2020

If no base gasket, could there be a leak and the mechanical resistance of touching the wood be just enough to let the computer’s full rich at idle hold it there?

Does an air leak on computer controlled saws typically show itself at idle or WOT?

drf256 · Feb 19, 2020

tree monkey said:
how much did you cut off the base? gasket or no?

.047

Manually relived the PITA ridge, you know about that one. Edges of extension relieved by base-it sits flush with no rocking. The intake area between the extension was relieved as well, it’s not hitting the round extension on the case behind the piston stuffer.

Factory gasket with a bit of motor seal rubbed on it for cheap insurance. No air leak.

No freeporting at TDC on exhaust floor.

Squish 18

drf256 · Feb 19, 2020

Spladle160 said:
I just don't understand how it could be a solenoid coil issue. The electronics only control the fuel right? I don't think a saw could run that fast with a fully closed throttle plate and no air leaks.

Billy Currie said:
Sorry, after watching the video I would be leaning more towards a fuel tank vent than a stopped up carburetor.

AKJonsereds said:
If no base gasket, could there be a leak and the mechanical resistance of touching the wood be just enough to let the computer’s full rich at idle hold it there?

Does an air leak on computer controlled saws typically show itself at idle or WOT?

Vent issue would cause lean condition at WOT, good thought but I doubt it. The saw will come to a slow idle after holding at WOT sometimes and also with slowing of the chain. If it was a linkage issue, slowing the chain wouldn’t stop the issue-if it could richen it up that way, it would do it already.

The saw controls idle by the richness of the idle mix. Carb bore’s aren’t airtight at the butterfly, there is always some air leak and we make it bigger or smaller by opening the throttle slightly with the idle screw adjustment. There is no throttle position sensor or idle screw on this saw. There is a choke position sensor which I believe tells the system which mode it’s in-hence the ability to actually idle for 30-60 seconds on idle (what other saw can do that?).

When time allows, plan is to check fuel line, add a new OEM filter and then retry. Next will be popping cover off after it occurs and seeing if there is any possible throttle linkage sticking while the issue is there. The design of the throttle system makes this all unlikely.

I’ll try motormix, why not. Cheap test and good to store saws with.

Have a solenoid and coil heading to me. My understanding is that bad solenoids will run super FAT, it makes sense that the factory default would be wide open-safer that way. It’s not doing that.

Last move will be changing popoff pressure. I’ve had issues with fuel flow on some MT before and this seemed to help, but I am still not fully sold on the lower popoff pressure thing. The area of the metering diaphragm and the fulcrum point of the lever shouldn’t really make that small difference appreciable. As long as the seat holds pressure, it should be good.

Most importantly, have to remember it’s just a fućking chainsaw, so I’m not too bent about it. It’s interesting though. Learning how this system works through trial and much error.

drf256 · Feb 19, 2020

Here’s the jug

drf256 · Feb 19, 2020

I know they aren’t IH quality, or Black Cat Performance, but I tried.

lehman live edge slab · Feb 19, 2020

I’m sure it won’t have anything to do with it but did you ever try another decompression button? Or had it been eliminated and plugged. And even if it was leaking I don’t know if it would mess with it.

Odd 462 MT Problem

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