Auto Tune is a better idea?

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MaddBomber

MaddBomber

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So, after having issues with my 550xp Mk2 (my first personal AT), and I've done a bunch of research to better understand it.
Firstly, the recalibration procedure is frickin weird. Maybe I'm wrong, but what I've read is the firmware samples cutting conditions after 30 seconds of WOT under load? If not under load it restarts the sampling process? Why? That's concerning to me, especially because my particular saw is a 50cc that'll be used primarily for limbing. I doubt it'll have many 30+ second cuts.
Secondly, the hot start process. What? Pump the bulb, set to choke, then click down to high idle, then pull. That's a good idea? Really?
I've grown up with just pulling a warm saw and it fires. From JRed 2071, 371/372, 346, 260/026, 660, 461 and even an old Mac 10-10. Just pull.
My 3 Stihl M-Tronic saws (261,362,462) have been flawless, and I believe they sample conditions multiple times a second...though, I could be wrong.
The recalibration procedure is easy and can be done in the back of a truck.
And the hot start is simply pull the starter....and it starts.
Why change it?
Now, I'm not knocking the performance and feel of AT saws, and actually prefer the 550 over the 261.
Maybe I'm wrong, but I can't understand the thinking.
 
MaddBomber

MaddBomber

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I realize how negative that post sounds. It's not intended to be. I am a convert to "smart" saws. They're performance is incredible.
I'm just flabbergasted at how Husqvarna thought it was a good idea to add steps, require specific situations, and go the opposite direction than most other engine management systems have established. Who said "yes" to that?
I've been a Jeep guy since birth.
As an example, to start my '46 it needs the throttle set, the choke engaged, and a feathering of the gas pedal.
My '75 needs the choke engaged and the gas pedal feathered.
My '01 just turn the key.
My '17 just turn the key.
Husqvarna seems to have went the opposite. Could you imagine buying a new Chevy truck, and to start it, you need to put it in park, then neutral, then park, then press the gass 3 times, then turn the key? And to set the engine to optimum efficiency you need to do ten laps on a racetrack at wide open throttle?
It's just strange to me.
 
czyhorse

czyhorse

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So, after having issues with my 550xp Mk2 (my first personal AT), and I've done a bunch of research to better understand it.
Firstly, the recalibration procedure is frickin weird. Maybe I'm wrong, but what I've read is the firmware samples cutting conditions after 30 seconds of WOT under load? If not under load it restarts the sampling process? Why? That's concerning to me, especially because my particular saw is a 50cc that'll be used primarily for limbing. I doubt it'll have many 30+ second cuts.
Secondly, the hot start process. What? Pump the bulb, set to choke, then click down to high idle, then pull. That's a good idea? Really?
I've grown up with just pulling a warm saw and it fires. From JRed 2071, 371/372, 346, 260/026, 660, 461 and even an old Mac 10-10. Just pull.
My 3 Stihl M-Tronic saws (261,362,462) have been flawless, and I believe they sample conditions multiple times a second...though, I could be wrong.
The recalibration procedure is easy and can be done in the back of a truck.
And the hot start is simply pull the starter....and it starts.
Why change it?
Now, I'm not knocking the performance and feel of AT saws, and actually prefer the 550 over the 261.
Maybe I'm wrong, but I can't understand the thinking.
Where did you find the hot start procedure? I have seen videos that were slightly different from that. Is there any documentation you can direct me to on the hot start procedure. Yes it shouldn’t be complicated. I have a 545 mkII and run into the same issues. When it runs it is just a wonderful saw so I am willing to work with what I have too.
 
sean donato

sean donato

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As my one and only new auto tune was a 2012 562xp, I think after some run time they figure out where they need to be, if you listen real close you can almost hear a lean ping every now and then. As I understand it it send this pulse every now and then and see how the saw reacts and adjusts accordingly.
 
bubmiller

bubmiller

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I realize how negative that post sounds. It's not intended to be. I am a convert to "smart" saws. They're performance is incredible.
I'm just flabbergasted at how Husqvarna thought it was a good idea to add steps, require specific situations, and go the opposite direction than most other engine management systems have established. Who said "yes" to that?
I've been a Jeep guy since birth.
As an example, to start my '46 it needs the throttle set, the choke engaged, and a feathering of the gas pedal.
My '75 needs the choke engaged and the gas pedal feathered.
My '01 just turn the key.
My '17 just turn the key.
Husqvarna seems to have went the opposite. Could you imagine buying a new Chevy truck, and to start it, you need to put it in park, then neutral, then park, then press the gass 3 times, then turn the key? And to set the engine to optimum efficiency you need to do ten laps on a racetrack at wide open throttle?
It's just strange to me.
I agree with you about the starting, however a vehicle has the advantage of full time power to the computer. Before the starter is engaged, it knows the baro, throttle position, temp, and last known fuel trims. And the fuel system and coils are precharged.

A chainsaw could give you one pull starts but then we'd complain about the weight of the battery.

Sent from my SM-A115AZ using Tapatalk
 
MaddBomber

MaddBomber

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Where did you find the hot start procedure? I have seen videos that were slightly different from that. Is there any documentation you can direct me to on the hot start procedure. Yes it shouldn’t be complicated. I have a 545 mkII and run into the same issues. When it runs it is just a wonderful saw so I am willing to work with what I have too.
Page 21 of the owner's manual.

IMG_20211012_180017788.jpg
 
MaddBomber

MaddBomber

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Don't get me wrong, my 462 flooded like crazy once while I was about to finish a back cut on a co-dominant elm. I was pulling on that thing like crazy and swearing at it like a drunken sailor when the wind picked up. If it wasn't for the tree being elm, I could have been in big trouble.
It's just a learning curve, and I'll get used to it, but it's the added steps that annoy me.
Again, I love this little saw. It just makes me scratch my head a little too often.
 

J D

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The compensation will be stored in non-volatile memory (ie doesn't require permanent power) otherwise it would be back to defaults, all history lost etc everytime the machine shut off.
It's a shame that it could be a much better system with a few minor tweeks, & even in it's current state it would be far more functional to the average user if they released some decent documentation explaining what it does, how it functions & how to calibrate it etc.
Hot start: pull chord to start
Warm start: choke out, choke in (set to high idle), pull chord to start
Cold start: prime, choke out, pull to "pop", choke in, pull chord to start
 
MaddBomber

MaddBomber

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The compensation will be stored in non-volatile memory (ie doesn't require permanent power) otherwise it would be back to defaults, all history lost etc everytime the machine shut off.
It's a shame that it could be a much better system with a few minor tweeks, & even in it's current state it would be far more functional to the average user if they released some decent documentation explaining what it does, how it functions & how to calibrate it etc.
Hot start: pull chord to start
Warm start: choke out, choke in (set to high idle), pull chord to start
Cold start: prime, choke out, pull to "pop", choke in, pull chord to start
What he said! Lol.
I absolutely agree. And I my personal experience, I rarely if ever "warm start" a saw. It's either cold or hot for me, unless breaking one in.... which is exactly what led to my issues and frustrations.
Never had any of these issues with an M-Tronic. That's not to say either system is better, but Stihl is definitely much more user friendly and informative.
Husqvarna has completely removed, or never put the recalibration sequence in/from their owner's manuals.
But if you don't calibrate it, there's a chance it'll go haywire and tune itself to something other than cutting wood. And the more heat cycles you do, the worse it gets.
 
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HumBurner

HumBurner

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Ideally, you would never run a saw for 30 seconds without a load. Not even 10 seconds unless you're trying to get oil flowing or unstick debris in the clutch housing.

You pretty much always tune any two stroke under load, except for the idle.


Second, if you aren't working all over and at drastically varying elevations, you should only need to set the AT every so often. You could probably get away with once or twice per gallon of gas, if you make your mix about the same each time.

If you're not cutting all that much, just get and keep a decent sized log around. Use it as your tuning log and make use of it when the saw doesn't sound or feel right.

Most of my autotunes don't need to be recalibrated very often. I work from sea level up to 3000'+ and there's little difference in air at that point.


Also, unless something has changed, for the AT to set its idle takes up to five minutes of idling. You can hear the changes the carb goes through.


Some folks may be better suited to manual carbs. There's unfortunately a few nice improvements in these newer, computer driven saws.
 

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