Wouldn't that entail a sensor on the motor itself instead of built into the coil?
I would think, and I have no idea on the actual function, that the temp sensor would help build the fueling curve.
MS261 Stalling/Not idling M-Tronic Issue?
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I would think, and I have no idea on the actual function, that the temp sensor would help build the fueling curve.
I don't think the temp sensor has anything to do with the fueling curve.
I interpret it as if they lean the fuel and the RPM doesn't drop then they leave it lean. If the RPM drops they add the fuel or more back.
I have the original patent. I'll see if I can PM it to you.
That's how I interpret it as well, but I was unaware of the temp sensor being a thing. It's also odd to me that the temp sensor is in the coil. If it was for building a fuel curve it should be at the carb inlet, if it's to monitor temperature of the motor it should be on the cylinder head or in the exhaust.
Regardless, the system works and is pretty simple in comparison to fuel injection as found on the 500I.
SteveSr
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I think that the temperature sensor (if it does truly exist) may be there to shut down the saw if the temperature gets too high. If not there would have to be a large offset between coil temp and air temp.
SteveSr
Addicted to ArboristSite
I would also be interested in a copy of the patent. Patents are public knowledge and not proprietary to Stihl so there is no need to PM it.
If that was the case putting it inside the coil is bad placement as it's far removed from the engine internals. Wouldn't you agree?
US Patent 8,161,931 B2
In a method for operating an internal combustion engine that has a starter device for starting the internal combustion engine and a device for supplying fuel controlled by a control device, it is determined whether cold start conditions or hot start conditions exist during starting of the internal combustion engine.
[...]
A simple configuration is provided when the control device is an electronic control unit and the temperature is measured in the electronic control unit. The temperature sensor for detecting the temperature can therefore be directly arranged on the circuit board of the electronic control unit so that no wiring is required.
Maybe I'll briefly describe what it's all about. In the M-Tronic, the temperature sensor is at least used to recognize warm and cold start.
As a result, there is one less lever position on machines with M-Tronic.
This patent describes it.
This patent does not mention adjusting the fuel-air mixture.
Way overthinking. It is a carburetor with a solenoid for mixture adjustment controlled by engine rpm. It can be reset to adjust to a new part, but will still be controlled by rpm. No other adjustments are possible, even with the diagnostic computer.
All I want to know is what to do to repair it. Not much different than any other saw.
As for the flywheel being the issue, never say never. The next one you work on will be that exact issue. Never fails.
All I want to know is what to do to repair it. Not much different than any other saw.
As for the flywheel being the issue, never say never. The next one you work on will be that exact issue. Never fails.
Ive posted on this before - I live in Colorado and saw up in the mountains. ( Last weekend I was sawing at 9000’). I also maintain saws for a number of non-profit groups. The most common saws I see are Stihl 261C, 362C, and Husky 545/550 OE series including the J’reds. They all have trouble starting here when hot. The Stihls just shut down but brand new coils seem to cure the problem. I routinely replace the black solenoids with green or white, new fuel filter, and latest coils. The old Huskys I will vent the cowl, like the new cowls, and do a muff mod if I have time. I have found them to be much more reliable starting by using the Husky “hot start” feature. Since us guys never read the Owners Manual, most operators don’t even know about it.
IMHO it is not really a coil “failure”, it is just the earlier coils weren’t programmed to go lean enough in these conditions, I have a 261C that is, IIRC, a 2022 and have never had a problem with it.
IMHO it is not really a coil “failure”, it is just the earlier coils weren’t programmed to go lean enough in these conditions, I have a 261C that is, IIRC, a 2022 and have never had a problem with it.
That's exactly it. Still a simple system and remarkably so given what it accomplishes. Very un-germanic engineering to say the least.
Above in response to @SteveSr request, for your convenience, I have posted a PDF of the Stihl US 8,544.448 patent, which describes the principle of the system that most of you guys associate as M-Tronic, a system that controls the fuel valve based on changes in RPM.
In fact, in addition to this, the system includes, closely related to the fuel valve control, the ignition timing control.
In addition to this, the system referred to by Stihl as M-Tronic also includes, at the very least, recognition of hot and cold engine starts based on, among other
things, the measured temperature, and selection of the appropriate amount of fuel for a given type of start based on this.
This is the US 8,161,931 patent that I also posted above to show that the temperature sensor is in the control unit.
I saw that. A BUS line is for transferring data between components, in a computer or whatever. In this case a control module and a carburetor.
If it does not have the return wires to the control module it is not M-tronic.
These three patents are interconnected, and there are probably more.
SteveSr
Addicted to ArboristSite
That's why I said... If it truly does exist... Unless it uses this coil temperature sensor to determine "cold start" conditions?
SteveSr
Addicted to ArboristSite
I don't know if I would consider 2 wires for controlling a solenoid and a throttle position switch a "bus". However, Stihl's scan tool does apparently read data from at ;east one of these wires.
Keep in mind that companies patent a LOT of ideas, a few of which might actually make it into real world products. If you really want to make your head spin just try matching Hewlett Packard patents to a specific inkjet print cartridge!
Yes, there may also be multiple patents on different aspects of the M-tronic system. Keep in mind that M-tronic began as Stihl's "intelligent engine management" I believe first used in an MS280 around 2010 or so.
2010 came the first saw with M-Tronic, the MS 441 C-M.
2006 (late 2006) was the MS 280 (with intelligent engine management) released.
2006 (late 2006) was the MS 280 (with intelligent engine management) released.
