stihl's mtronic

[a. palmer jr.]

I hope Stihl chainsaws don't go the way cars have gone, engine bays that are so crowded you can't even change a sparkplug and systems that you can't work on in the field or without a bunch of computers. Besides that I hate to take anything to a dealer to have it worked on..Sounds like maybe we should start hanging on to our old saws instead of buying new ones..

 

[jmssaws]

I don't know much about it other than it has to adjust for operating conditions
Wether it's from rpm or some other dumaflauchy.
I don't know how to use the correct word but I believe we're talking about the same thing.

 

[jmssaws]

I personally love mtronic because sending a ported saw off to the owner and not have to worry if it's tuned correctly and I'm tired of tuning saws. Lol

 

[a. palmer jr.]

Actually, the engine doesn't need a bunch of sensors like temp, rpm, throttle position, etc. It just means that the engine won't run at it's peak...

 

[kingOFgEEEks]

If I'm reading the Stihl manual correctly, it seems that RPM is the main evaluation criteria for the computer. If RPM's are too low, it leans the mix. If they're too high, it richens. I guess if Stihl programs a range of acceptable RPMs, and just has the computer adjust a little bit up and down every now and again, it should work without a bunch of other sensors?

 

[Duane(Pa)]

When you get down to brass tacks with your H screw, I am surprised by how little movement it takes. I can't imagine how they can be that "fine" with a solenoid.

 

[MustangMike]

I can not imagine they would not have liability for false advertising if there were not some temp +/or altitude monitor in there. Would be very easy to incorporate, and be beneficial on initial start up.

If it did not monitor fuel, you would not be able to let it idle on "start", it would choke out.

Also, per the advertising, there must be a limited memory function in the chip, otherwise there would be no reason for a "reset" function.

Other than those observations, I have no specific knowledge of how it works, but I believe it does adjust fuel & timing within a range.

 

[jmssaws]

It doesn't need a temp or altitude sensor because either affect rpm and then it will adjust for it.

 

[MustangMike]

How about on startup Jason? And it is very inexpensive to incorporate it, plus they state it in their advertisement.

I don't see why it would not have it.

 

[kingOFgEEEks]

I think we are all guilty of forgetting sometimes just how simple a 2 stroke piston ported engine really is. Air and fuel go in this end, witchcraft goes on in the middle, and noise and smoke go out the other end.

 

[Stackowood]

Hear Yugo Boyz...

Thanks, good reading. Interesting that you can do all the basic troubleshooting with the test leads and an Ohm meter.

Wondering if the test lead 5910 840 0903 is the same for all the newer models, or if it only fits the 441?

 

[jmssaws]

How about on startup Jason? And it is very inexpensive to incorporate it, plus they state it in their advertisement.

I don't see why it would not have it.

When you use the choke for a cold start it pushes a button to let it know it's a cold start and then fully adjusts the first time it goes wfo I think

 

[jmssaws]

All it needs to adjust for any situation is rpm.

 

[MustangMike]

Here are a few quotes from Stihl: Note it says adjusts timing & fuel metering, takes "external conditions into account" (temp/altitude?), and remembers settings under same external conditions. That is likely the part you builders like! I don't imagine they would open themselves to liability saying they do things they don't do. That said, it may all be much simpler than we think.

"The STIHL M-Tronic™ engine management system electronically controls the ignition timing and fuel metering in any operating condition, factoring in altitude and fuel quality. This system provides professionals with optimum performance, whether you are just starting to work or resuming after a break.

No Manual Carburetor Settings

The STIHL M-Tronic system electronically adjusts the fuel/air mixture in the carburetor for all operating conditions: start, idle, partial and full load. With the STIHL M-Tronic system always taking external conditions into account, you save time and money.

Memory Function
From the second you start it, the built-in intelligence of the STIHL M-Tronic engine management system begins saving you time – and money! STIHL M-Tronic remembers your last setting under the same external conditions and resets to it every time once the engine reaches full power."

 

[angelo c]

My 2017 KX250F has 2 fuel injectors and the ECU has different maps for fuel and ignition............ no O2 sensor

Kevin, how do you cut anything with that thing having wheels at either end....and is the "chain" square ground or round ?

 

[Redfin]

I can not imagine they would not have liability for false advertising if there were not some temp +/or altitude monitor in there.

Air density would probably be a better term for them to say the m-tron adjusts to. And no temp sender needed for that.

 

[paragonbuilder]

How about on startup Jason? And it is very inexpensive to incorporate it, plus they state it in their advertisement.

I don't see why it would not have it.

Here are a few quotes from Stihl: Note it says adjusts timing & fuel metering, takes "external conditions into account" (temp/altitude?), and remembers settings under same external conditions. That is likely the part you builders like! I don't imagine they would open themselves to liability saying they do things they don't do. That said, it may all be much simpler than we think.

"The STIHL M-Tronic[emoji769] engine management system electronically controls the ignition timing and fuel metering in any operating condition, factoring in altitude and fuel quality. This system provides professionals with optimum performance, whether you are just starting to work or resuming after a break.

No Manual Carburetor Settings

The STIHL M-Tronic system electronically adjusts the fuel/air mixture in the carburetor for all operating conditions: start, idle, partial and full load. With the STIHL M-Tronic system always taking external conditions into account, you save time and money.

Memory Function
From the second you start it, the built-in intelligence of the STIHL M-Tronic engine management system begins saving you time – and money! STIHL M-Tronic remembers your last setting under the same external conditions and resets to it every time once the engine reaches full power."

Mike it's worded very carefully, takes them into account. Jason is right, all that is needed is rpm to adjust for any condition.
But it's not looking for max rpm. This is a feedback system, it leans and richens the carb multiple times a second, think about it, if the saw is running at 10k, it's firing 166 times per second. It is looking for the saws reaction with each adjustment and then adjusts accordingly. If it were looking for max rpm it would run lean and burn up. They have tested to see how the saw reacts to these minor adjustments when the saw is running correctly and written it into an algorithm. It's actually very elegant.

They also allude to compensating with timing, but I believe that is just referring to the advance Tree Monkey spoke of in the first post, otherwise advancing the key would not work, the software would just compensate and put it back to stock.


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[mdavlee]

I know it won't run methanol. I did try it. Rpm gets too far out and it floods itself

 

[cease232]

I think RPM's could easily be interpreted as "external condition" external to the carb. Advertising semantics.


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[Mastermind]

I know it won't run methanol. I did try it. Rpm gets too far out and it floods itself

Yeah......I tried that too. lol