ms261c-m mtronic issue

[SteveSr]

How about this; re-gapped flywheel, torqued down 2 nuts holding air filter “manifold” to ensure snug fit thru intake series; started saw, runs better...still won’t scream. I unhook carb servo per your advice, saw dies. I expected that.

Trying to outsmart a F***ing computer! I forgot that the computer checks for a disconnected/open solenoid valve and will kill the ignition if it can't "see" the solenoid valve. The only way around this is to stick a resistor or spare solenoid to the disconnected harness.

 

[SteveSr]

Of course I look dumb, but I assure you, this filter looks fine. It passes air too. Just not enough apparently...

Try taking some brake cleaner with the straw and shoot a spot in the filter from the inside out and let it dry. Next check for light transmission with the sun or a flashlight to see if there is any/much difference. I would think that you should be able to see daylight through a clean filter.

 

[gmctyphoon]

So how’d everything turn out?

 

[quantico]

Older carb saws may not run perfectly, but there are far fewer potential problems.

 

[gmctyphoon]

OP said his problem was a dirty air filter. The last I checked “older carb saws” have an air filter too..

 

[L34]

Trying to outsmart a F***ing computer! I forgot that the computer checks for a disconnected/open solenoid valve and will kill the ignition if it can't "see" the solenoid valve. The only way around this is to stick a resistor or spare solenoid to the disconnected harness.

I tried a resistor on a 441c- didn't work.
Still shut down.

 

[SteveSr]

I tried a resistor on a 441c- didn't work.
Still shut down.

What happens with a spare/old solenoid?

Computer may also be looking for an RPM change with solenoid activation. If it doesn't find it it will also shut down.

 

[L34]

Believe ok with another solenoid.

 

[Everett Phillipston]

Just because I know everyone would want to hear this, AND TO SAVE MYSELF a little face, the real culprit here was a shaved key on the flywheel which was killing the ignition timing at mid to high rpm.
Installed a “new” used mtronic flywheel and she’s good to go.

I dug deeper because once I put the new filter on the following day, the symptoms were the same.

 

[PV Hiker]

If any can answer as to why a shear key on the flywheel would be shaved? What is the number of reasons why?

And why does Stihl form the key into the flywheel and not just use a replaceable key?

Thanks