ms261c-m mtronic issue

[Sepia]

Yes vacuum test is a crankcase leak down test. Mityvac makes a good pressure/vacuum tester.
https://www.ebay.com/itm/Mityvac-MV...738123&hash=item1eef8ab0b1:g:9sEAAOSw84Zb-y2p

 

[Everett Phillipston]

Yes vacuum test is a crankcase leak down test. Mityvac makes a good pressure/vacuum tester.
https://www.ebay.com/itm/Mityvac-MV...738123&hash=item1eef8ab0b1:g:9sEAAOSw84Zb-y2p

Thanks brah.

 

[Tobystihl]

Could possibly have a non mtronic flywheel fitted, hence the cut wires to the carb?

 

[Everett Phillipston]

Could possibly have a non mtronic flywheel fitted, hence the cut wires to the carb?

No offense, but that sounds like a reach. Saw idles for as long as I’ll let it when started cold in cold start position. I just broke it all down again, rechecked everything, put it back together. Tomorrow I’ll try brand new spark plugs and go from there.

I started messing with the 362c tonight as well. Idles, takes a little throttle, won’t scream wide open. Opened it up and you could hardly see the carb...buried under saw dust, grease, oil/fuel, & dirt. People who abuse and/or neglect their saws really grind my gears.

 

[SteveSr]

I believe that the default state for M-Tronic is lean (as in too lean to even run) as the EPA wouldn't want to allow the saw to run too rich with a malfunctioning system or cut solenoid wires. This sounds like the condition that you got. BTW, the M-tronic only controls the "H" carb circuit. The "L" and idle is controlled conventionally by just the carb. This would tell me that the solenoid is either clogged or not operating. To operate it needs power/pulse from the ignition computer/module.

The solenoid can be checked with a standard 9V battery after disconnecting the module. You should be able to hear it click. @backhoelover mightr be able to set you up with some further M-tronic troubleshooting information.

 

[Everett Phillipston]

I believe that the default state for M-Tronic is lean (as in too lean to even run) as the EPA wouldn't want to allow the saw to run too rich with a malfunctioning system or cut solenoid wires. This sounds like the condition that you got. BTW, the M-tronic only controls the "H" carb circuit. The "L" and idle is controlled conventionally by just the carb. This would tell me that the solenoid is either clogged or not operating. To operate it needs power/pulse from the ignition computer/module.

The solenoid can be checked with a standard 9V battery after disconnecting the module. You should be able to hear it click. @backhoelover mightr be able to set you up with some further M-tronic troubleshooting information.

Respect. Thank you

 

[Everett Phillipston]

No offense, but that sounds like a reach. Saw idles for as long as I’ll let it when started cold in cold start position. I just broke it all down again, rechecked everything, put it back together. Tomorrow I’ll try brand new spark plugs and go from there.

I started messing with the 362c tonight as well. Idles, takes a little throttle, won’t scream wide open. Opened it up and you could hardly see the carb...buried under saw dust, grease, oil/fuel, & dirt. People who abuse and/or neglect their saws really grind my gears.

362 is G2G. Cleaned the carb, adjusted mixture, and she screams.

The 261c-m is still a problem, albeit different now. New plug. Cleaned solenoid / carb. Hot starts and idles. Comes up on throttle a bit, but now hogs down if I chase the throttle hard. If I feather / tickle it strategically, it will climb rpms hesitantly and flatten out and then start to die. Back off throttle and it settles back down to idle. Idles fine.

Bout to bite the bullet and take it to the dealer to put it on the computer. Rather that then throw parts at it hoping.

 

[SteveSr]

The 261c-m is still a problem, albeit different now. New plug. Cleaned solenoid / carb. Hot starts and idles. Comes up on throttle a bit, but now hogs down if I chase the throttle hard. If I feather / tickle it strategically, it will climb rpms hesitantly and flatten out and then start to die. Back off throttle and it settles back down to idle. Idles fine.

Sounds like it is still way too lean to run. Either the solenoid is not being tickled by the module or the solenoid fuel path is still clogged. Try disconnecting the solenoid and see if it runs any different. If you can apply a 9V battery momentarily to the solenoid while it is running it should go to full rich and should rev up but run pig rich. This should tell you if it is fuel or electronics.

[QUOTE="Everett Phillipston, post: 7127358, member: 156650"Bout to bite the bullet and take it to the dealer to put it on the computer. Rather that then throw parts at it hoping.[/QUOTE]

Better check carefully to find a dealer who actually knows and understands how to work on these as well as has all the tools. Surprisingly, not all dealers have the tools or the knowledge to work on M-tronic equipment.

 

[Everett Phillipston]

Sounds like it is still way too lean to run. Either the solenoid is not being tickled by the module or the solenoid fuel path is still clogged. Try disconnecting the solenoid and see if it runs any different. If you can apply a 9V battery momentarily to the solenoid while it is running it should go to full rich and should rev up but run pig rich. This should tell you if it is fuel or electronics.

[QUOTE="Everett Phillipston, post: 7127358, member: 156650"Bout to bite the bullet and take it to the dealer to put it on the computer. Rather that then throw parts at it hoping.

Better check carefully to find a dealer who actually knows and understands how to work on these as well as has all the tools. Surprisingly, not all dealers have the tools or the knowledge to work on M-tronic equipment.[/QUOTE]


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. Hook it back up, start saw, runs, will take more throttle but still hesitant thru mid range. For ***** n giggles, I take air filter off...SAW SCREAMS AND REVS LIKE IT WAS BORN TO.

So...tell me, dirty air filter? Is it that simple? Looks fine, but I suppose it could be caked up/old/clogged micro pores.

 

[Ozhoo]

In the future...

 

[Everett Phillipston]

In the future...

View attachment 784700

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

 

[backhoelover]

I believe that the default state for M-Tronic is lean (as in too lean to even run) as the EPA wouldn't want to allow the saw to run too rich with a malfunctioning system or cut solenoid wires. This sounds like the condition that you got. BTW, the M-tronic only controls the "H" carb circuit. The "L" and idle is controlled conventionally by just the carb. This would tell me that the solenoid is either clogged or not operating. To operate it needs power/pulse from the ignition computer/module.

The solenoid can be checked with a standard 9V battery after disconnecting the module. You should be able to hear it click. @backhoelover mightr be able to set you up with some further M-tronic troubleshooting information.

with stihl u have to build your own testing box, looking thought school update box and see is I can’t find info

 

[gmctyphoon]

I have an 362c that acted similar. I tried everything obvious. Spent hours working on it.

After reading on AS I decided to gamble the $23 for a solenoid that was in stock at my dealer.

15 minutes of work later, the saw ran flawlessly.

Im not sure if the 261 and 362 valves are the same, but if they are maybe try swapping valves.

 

[backhoelover]

Correction u could use a battery 9v be carful.

 

[Everett Phillipston]

I have an 362c that acted similar. I tried everything obvious. Spent hours working on it.

After reading on AS I decided to gamble the $23 for a solenoid that was in stock at my dealer.

15 minutes of work later, the saw ran flawlessly.

Im not sure if the 261 and 362 valves are the same, but if they are maybe try swapping valves.

My 261c is mtronic; my 362c is not. Tomorrow I’m running down to the dealer for a filter and that should do it

 

[Iceboy]

I have an 362c that acted similar. I tried everything obvious. Spent hours working on it.

After reading on AS I decided to gamble the $23 for a solenoid that was in stock at my dealer.

15 minutes of work later, the saw ran flawlessly.

Im not sure if the 261 and 362 valves are the same, but if they are maybe try swapping valves.

I think there is only one for all saws!!!

Στάλθηκε από το SM-A920F μου χρησιμοποιώντας Tapatalk

 

[gmctyphoon]

I think there is only one for all saws!!!

I thought so.

 

[DND 9000]

I believe that the default state for M-Tronic is lean (as in too lean to even run) as the EPA wouldn't want to allow the saw to run too rich with a malfunctioning system or cut solenoid wires. This sounds like the condition that you got. BTW, the M-tronic only controls the "H" carb circuit. The "L" and idle is controlled conventionally by just the carb. This would tell me that the solenoid is either clogged or not operating. To operate it needs power/pulse from the ignition computer/module.

The solenoid can be checked with a standard 9V battery after disconnecting the module. You should be able to hear it click. @backhoelover mightr be able to set you up with some further M-tronic troubleshooting information.

Just a few things for clarification. M-Tronic controls both high speed and low speed. There are 2 passages after the solenoid valve for the fuel. One is for the low and the other is for the high. The amount of fuel is given through the switching cycle, that the control unit gives to the solenid valve. Also it is very very rare that a solenoid clogs because of dirt. The fuel passages in the solenoid are bigger as the ones in the carburetor. In the past, but that is also very rare, there were the one or other solenoid valve stuck because of old hardenig rest of 2 cycle oil. But this can only be the case when a machine sits for a long time.

It`s right that the solenoid switch function can be checked with a 9V battery, but it is better to not do that. In some cases it can fry up or destroy the control unit.

Also if you have disconnected the wires to the solenoid, or if there is a break in the wires, your saw will not run. In a condition like that you only get spark for a few seconds, because the control unit detects that there is no connection and shuts off the spark. The saw would also flood when there is no connection to the valve, because the valve is always open when unpowered.

 

[drf255]

Autotunes is great till it’s not. When there is an issue I just wanna treat the saw to a round of BFH fun.

The MT system does control idle and high as DND stated above. It searches for the highest rpm up to its rev limiter. So it will fatten or lean mix out for optimal power-it generally produces superior performance to a manual tune saw.

Most problems with the MT isn’t the MT itself. Very often it’s a fuel or air delivery issue and we blame the MT because it’s too difficult to diagnose.

I’ve had issues with my mix in a ported MT saw. The saw was cold and so was my fuel mix. I used 32:1 Motul800 which is very viscous and the MT couldn’t flow enough of the thick cold fuel, so it went all over the place. I swapped fuels and the saw ran fine. It was a real head scratcher.

Vac testing is always what one should do with issues, even with an MT saw. The MT will act strange and try to compensate for the leak. When there is a physical issue with the saw, the MT tries to compensate but can’t for all parameters and weird shít starts to happen.

Glad it was just your air filter.

 

[Everett Phillipston]

Autotunes is great till it’s not. When there is an issue I just wanna treat the saw to a round of BFH fun.

The MT system does control idle and high as DND stated above. It searches for the highest rpm up to its rev limiter. So it will fatten or lean mix out for optimal power-it generally produces superior performance to a manual tune saw.

Most problems with the MT isn’t the MT itself. Very often it’s a fuel or air delivery issue and we blame the MT because it’s too difficult to diagnose.

I’ve had issues with my mix in a ported MT saw. The saw was cold and so was my fuel mix. I used 32:1 Motul800 which is very viscous and the MT couldn’t flow enough of the thick cold fuel, so it went all over the place. I swapped fuels and the saw ran fine. It was a real head scratcher.

Vac testing is always what one should do with issues, even with an MT saw. The MT will act strange and try to compensate for the leak. When there is a physical issue with the saw, the MT tries to compensate but can’t for all parameters and weird shít starts to happen.

Glad it was just your air filter.

I friggin love this forum. Mad respect and thanks to all of you.