Ms 201 m-tronic stalling issue

[mtndragon]

I made the factory exhaust port probably 3Xs larger under the deflector and did the Speedcut 16" conversion this afternoon. After resetting the Mtronic, I cut cookies for a while on some 10" lodgepole and there's a definite improvement. I will run it over the next week in some oak in the foothills to really get a sense. Thanks again for the suggestions.

 

[NateSaw]

This may be too deep in the weeds but....

advancing the ignition timing you are maximizing the power stroke depending on the propagation of the flame front. IF you go slightly too far on your ignition timing you can compensate by adjusting the Carb to a rich condition. The fuel rich mixture will slow the flame front and get you back in the ball park but is not truly optimized. when you go under load the tune will clear up but will not be as good as if you have the timing and mixture tuned right. you are just covering a mistake. I believe Mtronic can provide enough fuel to mask an over advanced situation.

I wanted to reply earlier.. I can't recall who gave me the recommendation, but 5* was my advance in both saws. I used the wheel and made marks. I couldn't agree with you more David. That was always my experience when building cars. Anyhow, I got my hands on the most problematic saw and retarder back to stock and it stall even more now. All the suggestions made here have been in good directions. I'm trying to find little nuggets of time to grab the saw and try things. I'm also leary of loading up the parts gun as my bosses expense. However, @Ketchup mentioned green solenoids... I recall there being an update on these. The dealer I got the black one from seemed to glaze over my mention of that. What I need to do yet is call Josh at AK saw. He's the man. If he weren't 1.5hrs away I'd never go anywhere else. He's a wealth of factory knowledge. To sum up, my guts are on fuel... Or, the damn coil as @huskihl mentioned. I'm ready to take it hostage again and tear deep back into it, starting with basics like compression.

 

[NateSaw]

Another thing I considered... Making a change without resetting m-tronic is a fools endeavor... Can anyone teach this newb squirrel that ACTUAL way to reset? I've read varying methods. Which ones the one?

 

[Mastermind]

Another thing I considered... Making a change without resetting m-tronic is a fools endeavor... Can anyone teach this newb squirrel that ACTUAL way to reset? I've read varying methods. Which ones the one?

It depends on the mt version. Always try this one first.....

Start the saw on choke. Let it idle for 30 seconds. Then pin the throttle....it will sound like its studdering. Hold it wide open until it clears up and speeds up. Continue holding until it slows down again. Release the throttle and let it come to an idle. Shut it off and restart.

If you do the 30 seconds, then pin the throttle and it immediately speeds up, it has the older mt version. In that case, 90 seconds on choke....shut off, and restart.

Be sure that the chain brake is not engaged.

 

[Ketchup]

I wanted to reply earlier.. I can't recall who gave me the recommendation, but 5* was my advance in both saws. I used the wheel and made marks. I couldn't agree with you more David. That was always my experience when building cars. Anyhow, I got my hands on the most problematic saw and retarder back to stock and it stall even more now. All the suggestions made here have been in good directions. I'm trying to find little nuggets of time to grab the saw and try things. I'm also leary of loading up the parts gun as my bosses expense. However, @Ketchup mentioned green solenoids... I recall there being an update on these. The dealer I got the black one from seemed to glaze over my mention of that. What I need to do yet is call Josh at AK saw. He's the man. If he weren't 1.5hrs away I'd never go anywhere else. He's a wealth of factory knowledge. To sum up, my guts are on fuel... Or, the damn coil as @huskihl mentioned. I'm ready to take it hostage again and tear deep back into it, starting with basics like compression.

If you have two saws with the same carb I would swap the carbs first. It’s a 20 minute experiment at no cost. Coils could be swapped as well but it’s considerably more work.

The saw should run fine with the black solenoid unless you botched the install. I like the white ones but they aren’t listed for 201.

If the saw is dying when you drop the throttle I would suspect a stuck (open) Solenoid or bad main nozzle.

If the saw is struggling at idle and then dies, could be coil, solenoid, carb diaphragms, fuel lines. Lots of things.

Having a brand new carb or known good carb on hand is worth the money for fleet saws. I keep a 201 and 200 carb new in the box for troubleshooting.

 

[NateSaw]

It depends on the mt version. Always try this one first.....

Start the saw on choke. Let it idle for 30 seconds. Then pin the throttle....it will sound like its studdering. Hold it wide open until it clears up and speeds up. Continue holding until it slows down again. Release the throttle and let it come to an idle. Shut it off and restart.

If you do the 30 seconds, then pin the throttle and it immediately speeds up, it has the older mt version. In that case, 90 seconds on choke....shut off, and restart.

Be sure that the chain brake is not engaged.

Cigarette lighter clutch drum

 

[lehman live edge slab]

Thanks Kevin... We had discussed coils. I might just get one. I mean, that's the ecm. I did also forget to mention I had put a solenoid in the stock saw.

For some reason that carb is picky, I tried a solenoid in one also didn’t fix the idle. Tried some other stuff then after a bunch of wasted time it got a carb and was fixed.

 

[lehman live edge slab]

I'll have to look. Black I believe. That's what the local dealer sold me. I said to them I thought there was an update. It didn't look different than what I took out, iirc.

The green is the universal replacement they came out with for use in place of black that had seat wearing issues from contaminated fuel.

 

[lehman live edge slab]

Most m-tronic saws have no problem with timing advance. The 201TC doesn't seem to do well advanced....at least not with the same amount as we usually do. I believe that when Stihl created the TC they changed the ignition timing, because before it came out, the 201 needed to be advanced.

The first edition 201’s were real bad before the flywheel/coil upgrade gave them some power may have been an exhaust upgrade on first ones also

 

[lehman live edge slab]

I wanted to reply earlier.. I can't recall who gave me the recommendation, but 5* was my advance in both saws. I used the wheel and made marks. I couldn't agree with you more David. That was always my experience when building cars. Anyhow, I got my hands on the most problematic saw and retarder back to stock and it stall even more now. All the suggestions made here have been in good directions. I'm trying to find little nuggets of time to grab the saw and try things. I'm also leary of loading up the parts gun as my bosses expense. However, @Ketchup mentioned green solenoids... I recall there being an update on these. The dealer I got the black one from seemed to glaze over my mention of that. What I need to do yet is call Josh at AK saw. He's the man. If he weren't 1.5hrs away I'd never go anywhere else. He's a wealth of factory knowledge. To sum up, my guts are on fuel... Or, the damn coil as @huskihl mentioned. I'm ready to take it hostage again and tear deep back into it, starting with basics like compression.

If it was a new black solenoid unless it was bad from new I’m not thinking that it will be the issue. It’s not that they didn’t work it’s that they didn’t have a hard enough seat and wore out from contamination. I’m wondering if the timing advance is kind of a saw by saw situation? Have 4 new 201 tcm saws with 15 thousandths cut out of the key for advance and a 3/8” hole in muffler and they all have been going for a year to year and a half. Only ones back so far are dropped ones with broken handles and one the guy used as his only climbing saw all year needed clutch springs.

 

[NateSaw]

Update... I wish I would go with my guts more. When I initially pulled the carb apart I did a cleaning and a solenoid. Had I pushed the issue with the dealer, and got a green one, saw would've been fixed. Caleb, it was the solenoid and dirt. You were in it as well. They all get green. This saw didn't qualify as the prefix on the serial number fell below, @183. 187 is the cut off according to stihl. The green one worked anyway. Case closed.
I appreciate everyone's input.

 

[Mastermind]

Update... I wish I would go with my guts more. When I initially pulled the carb apart I did a cleaning and a solenoid. Had I pushed the issue with the dealer, and got a green one, saw would've been fixed. Caleb, it was the solenoid and dirt. You were in it as well. They all get green. This saw didn't qualify as the prefix on the serial number fell below, @183. 187 is the cut off according to stihl. The green one worked anyway. Case closed.
I appreciate everyone's input.

Good info. Thank you.

 

[NateSaw]

Good info. Thank you.

I've dissected some of these. The white and green ones are of a different design. More of a pintle style, like an injector... The old style are like a baffle... Stacks of spring plates. I don't know if that's consistent across the board between old and new. The comparison I did was between a black one off the 362 I ported, and the white(I think) one they supercede to. I'll get some pictures when I get home. The old style was guaranteed to fail, as debris would naturally get stuck between the plates. In fact, it's an inevitability.

 

[lehman live edge slab]

Update... I wish I would go with my guts more. When I initially pulled the carb apart I did a cleaning and a solenoid. Had I pushed the issue with the dealer, and got a green one, saw would've been fixed. Caleb, it was the solenoid and dirt. You were in it as well. They all get green. This saw didn't qualify as the prefix on the serial number fell below, @183. 187 is the cut off according to stihl. The green one worked anyway. Case closed.
I appreciate everyone's input.

Supposedly when in doubt use green it’s supposed to be the universal replacement

 

[NateSaw]

Here's an old style solenoid from the problem 201...popping out the gray retainer exposes the spring plate / valve/ meter thingy.
Next, here's the back of the springy thingy... It's two plates. The bottom plate is a smaller diameter, as this is what the electromagnet pulls to open up the gap between the four passages, and the spring plates spiral channels. It's a ginsu. I imagine this is their attempt to atomize or swirl the fuel preemptively... I'd be really very interested in weather the electromagnetic current is pulse width modulated (pwm), or continuously variable current...
Lastly, the veiw inside the solenoid with the guts removed... You can see the passages for fuel, the electromagnet, and if you look carefully, the step, or bevel that retains the spring plates outer diameter, and allows the inner plate to float.

 

[NateSaw]

Here I have a pick tool between the plates, illustrating the travel between them.. (exaggerated) I'd imagine no more than 0.005" gets it done. Maybe 0.010".

 

[NateSaw]

For the life of me, I was certain I had a new style white solenoid here. I cannot find it. Does anyone have one they can dissect?

 

[Mastermind]

For the life of me, I was certain I had a new style white solenoid here. I cannot find it. Does anyone have one they can dissect?

I only have a couple of new ones.

 

[NateSaw]

I only have a couple of new ones.

That's just the thing... The only one I thought had was too. I'm not seeing alot of the new style failing... If any so far.

 

[Ketchup]

I might have one…somewhere…