M-Tronic Problems Solved?

[bwalker]

Yeah they were great saws. My logging buddy used them for many years, but even he's gone to the 572xp as of last year or the year before. I don't think you could convince him to go back to a 372 anymore.

Exactly, because the new stuff is better.

 

[sean donato]

Exactly, because the new stuff is better.

Yep.

 

[holeycow]

Nope

 

[bwalker]

Nope

If more people were like you we would still be using misery whips and axes.

 

[LuDookie]

The only modern saws I haven’t run yet are the Stihl MS400 and 500i.

I’m not sold on paying over $1000 on 70cc saws. The Autotune system on the saw I wanted to last gave me issues beyond what the dealer could handle at the time. I know that’s where we are these days and I have comfort knowing with certainty that the saws I have will take care of me without dealer support, nearly forever.

I’m also not wanting to be the naysayer for others. Like I said earlier, if I were a logger and the saws were paying for themselves in the first few months, I’d have a reasonable approach.

 

[bwalker]

The only modern saws I haven’t run yet are the Stihl MS400 and 500i.

I’m not sold on paying over $1000 on 70cc saws. The Autotune system on the saw I wanted to last gave me issues beyond what the dealer could handle at the time. I know that’s where we are these days and I have comfort knowing with certainty that the saws I have will take care of me without dealer support, nearly forever.

I’m also not wanting to be the naysayer for others. Like I said earlier, if I were a logger and the saws were paying for themselves in the first few months, I’d have a reasonable approach.

Your dealer, like most are a bunch of morons.

 

[LuDookie]

Your dealer, like most are a bunch of morons.

I’ve had one Stihl dealer that was decent. Every other were worthless or didn’t know what they were talking about. I would just use them for chains and sometimes parts.

 

[bwalker]

I’ve had one Stihl dealer that was decent. Every other were worthless or didn’t know what they were talking about. I would just use them for chains and sometimes parts.

Sadly, this true.

 

[Michael Bradshaw]

First you don't need the programing. There's nothing you need to program. The solenoid is cheap, grab a spare and toss it in the tool box. Every so often it sends a lean pulse and looks for the rpm response, ie it doesn't care what fuel ratio you run, doesn't care how dirty the airfilter is up to a point. Heck they do their best to compensate for huge air leaks. They don't care if the saws been ported. It's a carb, with a fuel metering selinoid. Nothing more nothing less. There's all of 3 sensors in these things, non of which are prone to issues. The most comedic thing that the I want a regular carb saw is the fact the epa has had its fingers in saws for 20+ years and your still running new saws. Let alone typing on your phone/computer, driving fuel injected vehicles. Buy whatever makes you happy, doesn't matter to me one way or another just stop bashing something that has a proven track record of reliability.

Yes the EPA has tried to play around with carb saws for 20 years, but I know how to get around that. I was not looking to fix the programing, but wanted to see what and how the M tronic sampled all of the different parameters in order to make changes to the saw while it's running. By looking into the programing you can figure out if it is something really needed. To see if it is making adjustments that differ from the adjustments that can be made with a screwdriver. I agree that if it can make an adjustment because of an air leak, that can actually save you from blowing up your saw. I have only experienced one major air leak in all my years. At the time I was forced to shut the saw down until I got back to the barn and fix the leak. At no point did I say that the M Tronic was junk, in fact the opposite. I have said to others that I think that for most people out there who buy chainsaws for storm damage cleanup or what not, would benefit from it because they have little to no knowledge of 2 cycle engines. I talked about the MS 192TC that I inherited from my father. It has been a trouble-free, great running saw, but there has been only a few times, when cutting 12 inch limbs into18 inch lengths making7 cuts, one right after the other, the saw got hot and stalled out, and a pain to restart, and it did. My other saws are Husqvarna 51, 55, 262X, and 268. My Stihls 26, 250, 192TC, and the one I just purchased 462. I wanted the 462 because most of the saws I have are pushing 20-25+ years old and parts are getting harder and harder to find. At my age, I also wanted a saw that had tons of power and lighter weight and will run for a long time with regular maintenance for years before needing any kind of major repair. Plus, the added benefit of what I know. Just like my only vehicle. A 1978 GMC 3/4-ton, 4x4 with a 454 Cid. I do not have a cell phone, and this computer was given to me 10 years ago so I could keep in touch with the family, and this is the first and only forum I signed up to. I have learned a lot through this conversation that I need to be very clear about what I'm typing. I apologize if you thought I was bashing the Stihl saws, that was not my intension I was more frustrated at the time of my first post with the salespeople then the company. I from now on try to make myself clear on whatever I'm trying to say, I sometimes get a little long winded. Take care and have a good night.

 

[Captain Bruce]

This is just it. A bunch of Luddites afraid a simple compensating carb. Even more strange is some of these same guys embrace the 500I, which is way more complex.

and the $1500 bucks

 

[bwalker]

and the $1500 bucks

All things considered that's dirt cheap. Nost here are hobbyists and as such its a damn cheap hobby.

 

[ZeroJunk]

I have a MS362C and a MS361 . To be honest, I would just as soon have one as the other.

I have $50 in the MS362C and about $140 in the MS361. Both are in good shape.
But, I usually pick up the MS261. I have $40 in it.
I had a MS500I for a little while just to play with. I needed it like another hole in my head.
Working at the Stihl dealership has it's perks.

 

[LuDookie]

All things considered that's dirt cheap. Nost here are hobbyists and as such its a damn cheap hobby.

Just to set the tone - friendly banter to follow… my 395xp was less, and it’ll eat that 500’s lunch. $1500 is a lot to swallow for a saw. That’s a fuel injection tax right there. You’d think the lefties would give us some sort of incentive to run these “epa saws”. Destroying chainsaws, the planet and the country , Benjamin’s at a time.

 

[sean donato]

Yes the EPA has tried to play around with carb saws for 20 years, but I know how to get around that. I was not looking to fix the programing, but wanted to see what and how the M tronic sampled all of the different parameters in order to make changes to the saw while it's running. By looking into the programing you can figure out if it is something really needed. To see if it is making adjustments that differ from the adjustments that can be made with a screwdriver. I agree that if it can make an adjustment because of an air leak, that can actually save you from blowing up your saw. I have only experienced one major air leak in all my years. At the time I was forced to shut the saw down until I got back to the barn and fix the leak. At no point did I say that the M Tronic was junk, in fact the opposite. I have said to others that I think that for most people out there who buy chainsaws for storm damage cleanup or what not, would benefit from it because they have little to no knowledge of 2 cycle engines. I talked about the MS 192TC that I inherited from my father. It has been a trouble-free, great running saw, but there has been only a few times, when cutting 12 inch limbs into18 inch lengths making7 cuts, one right after the other, the saw got hot and stalled out, and a pain to restart, and it did. My other saws are Husqvarna 51, 55, 262X, and 268. My Stihls 26, 250, 192TC, and the one I just purchased 462. I wanted the 462 because most of the saws I have are pushing 20-25+ years old and parts are getting harder and harder to find. At my age, I also wanted a saw that had tons of power and lighter weight and will run for a long time with regular maintenance for years before needing any kind of major repair. Plus, the added benefit of what I know. Just like my only vehicle. A 1978 GMC 3/4-ton, 4x4 with a 454 Cid. I do not have a cell phone, and this computer was given to me 10 years ago so I could keep in touch with the family, and this is the first and only forum I signed up to. I have learned a lot through this conversation that I need to be very clear about what I'm typing. I apologize if you thought I was bashing the Stihl saws, that was not my intension I was more frustrated at the time of my first post with the salespeople then the company. I from now on try to make myself clear on whatever I'm trying to say, I sometimes get a little long winded. Take care and have a good night.

I understand your curiosity, however there's nothing to looks at in the programming. It's a bunch of fuel and timing maps for various temps etc. There are 3 sensors that I know about rpm, temp and possibly a throttle position sensor. Havent bothered to see if its there on the 400. No sensors are serviceable, but non of the components are prone to failure either. At least not anymore then an ignition module on the same carb version saw. Few extra wires. It's still a carb under the hood.
Yes I agree, 90% of people can't tune any engine to save their arse. I'm not one of them, I have many old saws, and lots of other 2 stroke engines, both high and low performance. I'd still rather take my 400cm with me and let the 365, or 359 husqy, 605 Mac, or David bardley, or homelite sit at the house. Heck I don't even use my 394xp unless I need to mill boards. My 390xp still sees regular use but that's less since the 400 pulls a 24" bar in hardwoods fine.
I'm very curt and blunt, I'm like this when talking in person as well. So don't take offense. recently there's been a lot of people bashing a system that is very simple and acting like the world has fallen apart because a saw has a few additional parts. Among other things. I see this as ridiculous. Most I'd also guess haven't used it, or are so stubborn if they did use it it, would still reject the idea of them not being in control. It's nothing personal against you, just the theme in general.

 

[LuDookie]

Truth is, I’d take any new saw in a heart beat. Just got money tied up everywhere else right now. Raising 3 teenagers.

 

[lone wolf]

Just to set the tone - friendly banter to follow… my 395xp was less, and it’ll eat that 500’s lunch. $1500 is a lot to swallow for a saw. That’s a fuel injection tax right there. You’d think the lefties would give us some sort of incentive to run these “epa saws”. Destroying chainsaws, the planet and the country , Benjamin’s at a time.

And it is a lot heavier ! I would rather have the 500I.

 

[ZeroJunk]

I understand your curiosity, however there's nothing to looks at in the programming. It's a bunch of fuel and timing maps for various temps etc. There are 3 sensors that I know about rpm, temp and possibly a throttle position sensor. Havent bothered to see if its there on the 400. No sensors are serviceable, but non of the components are prone to failure either. At least not anymore then an ignition module on the same carb version saw. Few extra wires. It's still a carb under the hood.
Yes I agree, 90% of people can't tune any engine to save their arse. I'm not one of them, I have many old saws, and lots of other 2 stroke engines, both high and low performance. I'd still rather take my 400cm with me and let the 365, or 359 husqy, 605 Mac, or David bardley, or homelite sit at the house. Heck I don't even use my 394xp unless I need to mill boards. My 390xp still sees regular use but that's less since the 400 pulls a 24" bar in hardwoods fine.
I'm very curt and blunt, I'm like this when talking in person as well. So don't take offense. recently there's been a lot of people bashing a system that is very simple and acting like the world has fallen apart because a saw has a few additional parts. Among other things. I see this as ridiculous. Most I'd also guess haven't used it, or are so stubborn if they did use it it, would still reject the idea of them not being in control. It's nothing personal against you, just the theme in general.

I am not a certified Stihl tech, never been to a class. And, don't know if they would even get in to it. But, I would be curious to know how the M Tronic works. I can repair them easy as anything else.

But, I would like to know what the signal is to the solenoid. Like does the voltage increase/decrease to open close the solenoid ? Is it a gradual opening or does the solenoid open and close at a varying rate depending on demand ? Is it DC ? How do they rectify it ?
How does the RPM talk to the ignition coil ? Where is this temperature sensor located ?


I have built some reasonable complicated circuit boards to control bias, time delays, step start circuits, solid state relay switching, that kind of thing.

So, just curious. Not that you need to know to repair one that has been dropped out of a tree or run over.

 

[ericm979]

This explains a lot about Mtronic:

https://www.stihl.com/engine-technology-fully-electronic-engine-management.aspx
this patent is even more detailed:

https://patents.google.com/patent/US8544448B2/en
The Abstract:
For operating an internal combustion engine with a combustion chamber delimited by a piston driving a crankshaft in a crankcase, with a device for supplying fuel, an ignition device, and an electronic control unit, wherein a correlation between a power output of the internal combustion engine and a lambda value in the combustion chamber is defined by a power output curve that has a first ascending branch, a maximum, and a second descending branch where the lambda value is smaller than 1, the position of an operating point of the internal combustion engine is determined by adjusting the ignition timing to an adjusted ignition timing and evaluating the engine speed reaction caused by the adjusted ignition timing. The supplied fuel quantity is changed as a function of the determined position of the operating point when the determined position of the operating point is not a desired operating point.

Lamda is fuel/air ratio where a lambda of 1 is the stoichiometric value of 14.7:1. The "first" and "second" are patent-speak for logical branches. So basically the Mtronic works by varying timing and seeing how that affects rpm, then changing the carb's fuel output to optimize the rpm.

All it needs is the crank mounted rotor to provide the rpm signal and also power to run the Mtronic cpu. No throttle position sensor. The patent does not mention a temperature sensor but the Stihl litterature does, so maybe they added it. Same with the switch to detect starting position on the control lever. No mention of how the carb solenoid is driven, i.e. is it held open a varying amount or does it constantly cycle from closed to open, varying only the time it's open, like a fuel injector in a car? I expect the former as the fuel is not under high pressure as in a car FI system so it would not be able to flow out quickly.

 

[ZeroJunk]

So, am I correct that the temperature sensor is in the control module itself and the heat transferred through the crankcase wall is calculated ? And, higher RPM increases the energy produced and is somewhat inversely proportional to the solenoid opening so as the RPM drops more fuel is supplied ?

I wondered about that short jumper, but it tells the control module the position of the choke.

I would still like to know what that signal to the solenoid actually is, a varying DC voltage or a varying signal rate.
Not that it makes a ****.

 

[LuDookie]

Lol, this took a weird turn. We went from simple to “stoichiometric”!
Is that a woke term for righty tighty, lefty loosey?