Are M-Tronic & AutoTune holding up?

[MaddBomber]

Just talking to a Stihl certified tech about the longevity of C-Ms. He's seen no issues other than a few solenoids. The area has mostly homeowners and landscapers with few to no true loggers.
I've heard some say that they run too lean, so 40:1 or 32:1 is needed.
I've heard that true timberman avoid them.
I know of a handful of reputable tuners that won't touch any saw with wired carbs.
So, my question is; is this true? Do any full time, 6hr a day, 75+ tree a day loggers run them? If so, how are they holding up?

 

[lone wolf]

Just talking to a Stihl certified tech about the longevity of C-Ms. He's seen no issues other than a few solenoids. The area has mostly homeowners and landscapers with few to no true loggers.
I've heard some say that they run too lean, so 40:1 or 32:1 is needed.
I've heard that true timberman avoid them.
I know of a handful of reputable tuners that won't touch any saw with wired carbs.
So, my question is; is this true? Do any full time, 6hr a day, 75+ tree a day loggers run them? If so, how are they holding up?

I am a Tree Service and my 241C's are still running fine after a couple years.

 

[holeycow]

Hours?

 

[holeycow]

Most pros run them and change them out every two years just like they always have with any saw.

Many refuse to run them and just keep rebuilding their old saws.

 

[Huskvarna hotellgäst]

When it goes wrong, you can't fix it with a screwdriver but it can actually tell you what the problem is, and in the admittedly few cases I've seen. it hasn't been in the AutoTune carb.

AutoTune and M-Tronic are the same patent implemented by different engineers, the primary benefit being to minimise noxious emissions by maintaining the ideal air/fuel ratio at all times under a wide range of conditions and/or faults by continuously adjusting the air flow in response to continuous monitoring of key engine parameters.

The secondary benefit is that the engine runs properly all of the time whereas even the most expert manual tuning provides the ideal air/fuel ratio in only one or two operating modes.
E.g. at idle it's too rich.
When starting it's too lean.
Accelerating from idle it's too lean.
Changes in air pressure, oil mix, altitude....I'll stop there.

Given equivalent reliability over time, the former should be streets ahead of the latter.

 

[holeycow]

Two strokes like to burn oil.

Running on the edge of lean does not use enough oil.

The programming is wrong due to epa.

IMO

 

[Mad Professor]

When it goes wrong, you can't fix it with a screwdriver but it can actually tell you what the problem is, and in the admittedly few cases I've seen. it hasn't been in the AutoTune carb.

AutoTune and M-Tronic are the same patent implemented by different engineers, the primary benefit being to minimise noxious emissions by maintaining the ideal air/fuel ratio at all times under a wide range of conditions and/or faults by continuously adjusting the air flow in response to continuous monitoring of key engine parameters.

The secondary benefit is that the engine runs properly all of the time whereas even the most expert manual tuning provides the ideal air/fuel ratio in only one or two operating modes.
E.g. at idle it's too rich.
When starting it's too lean.
Accelerating from idle it's too lean.
Changes in air pressure, oil mix, altitude....I'll stop there.

Given equivalent reliability over time, the former should be streets ahead of the latter.

If I have a good ole carb tuned it runs nice, from idle to WOT.

If it's rich at idle you don't have LO and idle set right together

If it is lean starting you have a choke problem.

If it is lean off idle, LO is too lean.

Air pressure? Are you talking cat 5 Hurricane vs Bermuda High for "air pressure"?

Altitude will make a difference, but not much unless it is several thousand feet. A clogged air filter is worse/as bad

I like being able to fix a carb without going to a dealer, quick with just a screwdriver, and a $10 rebuild kit if needed. For ONE dealer visit I can buy carb kits for several/many saws

I have some 038 carbs that have never had new parts, yet, and still run fine. When they act up I have kits that will cost me less than a dealer visit, and lost time going back and forth.

P.S. I like old cars too, with a 4150 Holley and only vac lines for a dist advance and PCV

 

[foeke]

Adding more oil will make a saw run even leaner.
Just run the normal 1:50 especially with a smart carb.

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[holeycow]

Yes it will.

Thats why its nice to be able to compensate for the necessary added oil.

 

[Mad Professor]

Adding more oil will make a saw run even leaner.
Just run the normal 1:50 especially with a smart carb.

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I tune a saw for ONE fuel, oil, mix/ratio. Same quality oil, 100LL AV fuel or non-ethanol premium, mix/ratio.

I make a log of this. If I can't get same fuel/oil, I retune/adjust. I log that. If I have to switch fuel again, it's just a fraction of a turn on HI/LO/idle.

If that don't make saw run right, there is a deeper problem.

Saws I mill with I do the same, but more oil in mix. So I log in a record, for milling mix and firewood/logging mix.

P.S. I make out a spreadsheet for these tuning logs. Print out a few copies. Keep one in the tool shed, one in woods tool box, a spare if computer craps out.

 

[Huskvarna hotellgäst]

If it's rich at idle you don't have LO and idle set right together

If it is lean off idle, LO is too lean.

A standard carb can't be set to idle as lean as possible and also pick up from idle without faltering.
An autotune carb can because the solenoid momentarily closes the air control vane to increase vacuum when you open the throttle.

I completely understand the preference for simply adjustable preset jet carbs. All my current saws have them and I get a kick out of being able to pick up someone else's saw that "never runs properly" and have it running sweetly within 2 minutes.
However, I also have a 10 year old car with multipoint injection that has only ever had the oil and the timing belt changed and still runs as sweet as a nut and passes emission tests every year. Much more complicated than the pair of a dual-throat Webers on the cars I used to race and yet more reliable too. It's nice to look back but there's no going there.

 

[catbuster]

They last plenty long. Don’t worry about it. If I can get 3,000 hours out of a 441 or 661, you can too.

 

[champion221elite]

I have a Husky 555 with Autotune and it's been good so far. Bought it used from a member here on AS. Its a 2016 model with very low hours. So far, so good...hoping it stays that way.

 

[Matt Hogden]

I've got 2 M-Tronics and they are fine.

Sent from my SM-A505YN using Tapatalk

 

[holeycow]

Given equivalent reliability over time, the former should be streets ahead of the latter.

Unfortunately it's not. The EPA mandates too-lean settings. Simple as that.

However, most saws still survive in-spite-of. Two strokes are tough, generally.

 

[Brent Nowell]

Adding more oil will make a saw run even leaner.
Just run the normal 1:50 especially with a smart carb.

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This would be true only if the jets were fixed and they are not. The auto tune compensates for oil mixture only because it only looks for factors that have nothing to do with the oil and everything to do with rpms/temp/throttle position. If it starts to run lean by sensing too high an rpm it compensates by opening up the main jet. Even if you had 32:1 it will add enough of the oil/gas mixture to create the same power as say with a 50:1 mixture

How do I know this?
Well my plugs come out tan on the insulator every time and I run 32:1

 

[SawTroll]

Yes it will.

Thats why its nice to be able to compensate for the necessary added oil.

Surely - if the carb setting is exactly the same.

The AT and M-tronic will compensate automatically though, and a correct manual tuning for each oil ratio will of course compensate as well.

Of course, a tank of fuel will run empty a little faster with more oil in the mix, as the carb setting needs to be richer - but I doubt that many will notice the difference.

 

[Brent Nowell]

Surely - if the carb setting is exactly the same.

The AT and M-tronic with compensate automatically though, and a correct manual tuning for each oil ratio will of course compensate as well.

Of course, a tank of fuel will run empty a little faster with more oil in the mix, as the carb setting needs to be richer - but I doubt that many will notice the difference.

Bingo bango exactly

 

[drf255]

They will run leaner on thicker oil ratios. I had to go to 40:1 on mine instead of 32.

Also depends on how viscous the oil is that you use. This is especially true on the smaller models. The MT can’t richen the ratio enough to flow the thicker mix, especially in colder temps and ported saws.

The pros of MT is the saw is always in tune to make peak power. No need to play with the carb with different mixes or ambient temps/elevations. If you need to lend a saw out (taboo-I know) the chances of getting back a toasted piston is far less. I like them a lot. Start the saw and cut wood and that’s it.

The cons:

When there is a problem you are beholden to a dealer or the need to start swapping parts. You’ll find yourself wanting to smash the saw with a BFH. I’ve been there.

At least Husky offers software for a person to possibly troubleshoot their saw, Stihl does not. Stihl also swapped their solenoids to a newer design which is much pricier than its predecessor.

If you know your way around a saw and are diligent about checking tune, there is no need for an auto tune saw. Many of the saws I run are 30+ years old. I doubt the computer saws will last that long, I guess we will have that answer in another few decades.

 

[Mad Professor]

A standard carb can't be set to idle as lean as possible and also pick up from idle without faltering.
An autotune carb can because the solenoid momentarily closes the air control vane to increase vacuum when you open the throttle.

I completely understand the preference for simply adjustable preset jet carbs. All my current saws have them and I get a kick out of being able to pick up someone else's saw that "never runs properly" and have it running sweetly within 2 minutes.
However, I also have a 10 year old car with multipoint injection that has only ever had the oil and the timing belt changed and still runs as sweet as a nut and passes emission tests every year. Much more complicated than the pair of a dual-throat Webers on the cars I used to race and yet more reliable too. It's nice to look back but there's no going there.

When your 10 year old car does start acting up, it will go to the scrapyard rather than getting fixed, because You won't be able to fix it, and the dealer will want so much $$$ you'll have to take out a loan.