MT/AT vs old fuel

[J D]

So I've been wondering... what happens if an M-Tronic/ Auto-Tune saw gets run on old gas?
I know with a traditional carb the saw will run like crap, but unless it's particularly high compression & starts detonating, or I decide to **** with the carb, old fuel is unlikely to cause any issues other than poor performance.
I would suspect that in the same situation an AT/MT carburetor could start leaning the saw out to achieve the desired rpms... potentially leading to P/C damage?
Interested to hear any further insight those in the know might have to pass on

 

[Dennis Gauge]

I think that would require knowledge about what auto-tune tunes for. Does it tune for mixture, or RPMs?

Seems like tuning for RPMs alone would be the entirely wrong way to go about it. I would have to think it does something a bit more sophisticated than that.

 

[Mad Professor]

Given time E10 will absorb water and separate. Then it make snot that likes like phlegm from pneumonia.

 

[cscltd]

We were told that mt/at can compensate for some poor/old fuel, but didn’t mean you could run skunky old crap through it and expect no issues.

 

[J D]

My understanding is neither MT or AT work of any input more than throttle position sensor & RPM readings. Successive approximations are made & modulation of the fuel solenoid is adjusted over time.
I haven't run any old E10 or "skunky old crap" fuel through anything, but I'm sure plenty of people have done so unintentionally at some stage so I'm curious how things play out with the "smarts" in that situation

 

[cookies]

Theres a reason stihl had to come up with those newer orange filters, skunky old gas has particulates of varnish in it.

 

[stihltech]

It is a carburetor. Bad fuel will do the same thing to it as a non Mtronic. Don't let the IT HAS A COMPUTER!!!!!! idea change your mind. Same diagnosis until you get to fuel solenoid. 90 day old fuel is garbage and will cause issues. And I don't care what non ethanol or additive you use. See it the shop daily. A clear quart glass jar is one of my best diagnosis tools.
Yes, use the orange filter!

 

[sean donato]

At/Mt work the same way. The few sensors sends feedback to the computer which sends a lean pulse every now and then and looks for an expected rpm change. It's changes fueling based on the expected rpm. It's a very good system that requires minimal sensors. Really outside of the electronics and the fuel solenoid it's still a basic carb under the hood. Everything is effected by bad fuel doesn't matter if there's an adjustment screw or not.

 

[huskihl]

Old gas can cause detonation damage in either if the operator doesn’t pay attention

 

[bwalker]

At/Mt work the same way. The few sensors sends feedback to the computer which sends a lean pulse every now and then and looks for an expected rpm change. It's changes fueling based on the expected rpm. It's a very good system that requires minimal sensors. Really outside of the electronics and the fuel solenoid it's still a basic carb under the hood. Everything is effected by bad fuel doesn't matter if there's an adjustment screw or not.

Absolutely correct. This idea that AT/MT are some sort of complex vodoo magic is ridiculous. In reality they are a dead ai ple solution for a real problem. And the latest versions work very well.

 

[bwalker]

Old gas can cause detonation damage in either if the operator doesn’t any attention

Absolutely. Alot of the high octane component are what evaporate first. As a result you might have something with a drastically lower octane level than when fresh.

 

[Husky77]

Good fuel, good oil and clean air and with the right carb setting auto or manual you'll have a good running saw, will it cut good? Maybe not as well as expected because the art of sharpening hasnt been learnt yet. It's a combination of knowing what is right and how to do it.

 

[J D]

I think the motive behind my original post may have been misconstrued (or I didn't explain myself well enough).
Obviously no one should be running old fuel, that goes without saying. BUT... I (like many of you) still see plenty of saws that have issues because of old gas (& most our gas is ethanol free).
One would like to think that someone who has made the investment in a quality AT/MT saw would know well enough to use fresh mix, but we all know this won't always be the case. So... I'm curious as to how an auto tune or m-tronic carb would vary the mix in that situation, & to what end