Topic: Megasquirt (microsquit)

[emsvitil]

I'm trying to figure out the logic behind Megasquirt.


I downloaded the free Tunerstudio software to get an idea (helped a little).


What I've found online, is more a cookbook than how it works.     


Some features just say 'for advance users only' giving you no idea as to what they're doing.


But, I'm not going to reprogram the code in the box.




So I'm looking for something in between the 'cookbook' and the 'coder'...………..




thanks

[kneedownnate]

I can try to get my brother to post on it, but he really doesn’t like coming over here.  He’s used it for many years on a n/a mr2 with great success and has tried explaining it to me, to great frustration for us both

[emsvitil [OP]]

I'm just wondering if there's a manual somewhere that's above 'Megasquirt for dummies' and below 'customize your Megasquirt firmware code'

You mostly find  'for dummies' but I've found lines of code too.

[te51levin]

Ed,

I'm the brother in question.  My setup is MS1 on a V3.0 board running MegaSquirtnSpark-Extra firmware (MS1 doesn't do spark control on its own).  Ignition is distributorless wasted spark, using a Ford EDIS-4 coil pack with two coil drivers on the MS board to eliminate the EDIS module along with a 36-1 tooth Ford crank trigger wheel.

All of this is ten or twelve years old and I have not kept up with MS developments since then, so I am far from an expert, but maybe I can point you in the right direction.  What are you trying to do, and what questions are you trying to find answers to?

[emsvitil [OP]]

Hopefully for a future retirement project...…………..  (when I can tap into my 401k(s) and afford it.)


Microsquirt control of an experimental aircraft engine.     Lycoming (or clone)  IO-360 flat 4.


VE table 1 would be speed density or %baro     (map and rpm)     plus barometric correction (probably)

kPa changes primarily due to altitude not throttle position.

I kinda understard speed density with barometric correcton, but not %baro.



VE table 2 can be used to modify VE table 1 either additive or multiplicative.  (Planning alpha-n (TPS & RPM) or MAF (MAF & RPM))
Variable voltage of TPS or MAF signal to vary Air fuel mixture.    VE1 table * VE2 table.

VE trim tables 1 & 2 to modify/balance the 2 banks of injectors

AFR table 1 to set air fuel ratio (about 12:1 everywhere)



Next question


Is fuel calculation   ((VE 1 table +or* VE 2 table) * (VE trim)) * (AFR table)

or           ((VE 1 table * VE trim) +or* VE 2 table)   *  (AFR table)



Finally,   VE table 3 can be set to replace VE table 1 +or* VE table 2.

Are trim tables then used with VE table 3 or not used at all with table 3?


Hope this is understandable


 thanks

[te51levin]

Well, ain't that a thinker.

You're looking at features or parameters that my simple setup doesn't include, so I'm out of my depths here.  I only have one VE table.  That said, once you actually get things put together and start tuning, the effect of those will start to become clear.

You're going to run leaner than 12:1 at economy cruise, aren't you?

An aircraft application has some advantages in that the throttle position, load, RPM, and temperature are far more static and have far narrower operating ranges than an automotive application. Acceleration, throttle response, cold drivability, etc, are non-issues.  So you won't need to worry about them the way you would on the ground.  That may justify simpler hardware and firmware than you are thinking of.

An IO-360 is already injected. What are you hoping to gain by going to MS?

[emsvitil [OP]]

In reverse order

Mechanical fuel injection vs electronic.    Fuel balance starts to goto hell when you get below 7-8 gallons per hour.    Also fuel balance tends to be only valid at one particular fuel flow setting with mechanical (tuned with nozzle orifice size).
(side effect, something to tinker with to keep my mind active)


Microsquirt looks pretty simple.    First stage would be magneto replacement(s).    Then I have box that can handle fuel.     I'd actually have 2 microsquirts.    Each runs half of engine, but capable of running full engine. (it's an airplane............)

Yep,  that's where VE table 2 comes in.     If the VE table 2 lookup is 70%, I'll get 17:1 AFR (VE1*VE2).    VE table 3 mostly as a stupid simple, limp home mode.


Would initially be add on (parallel)  to mechanical system.      Then switchable in flight.     Can't stop and pullover when you're in the air.


I'm more or less trying to figure out if my idea would work, and what piece of equipment it would work on.   I hate it when you've missed something and your project gets much much more complicated.


(Retirement project: Vans RV-7 taildragger if you're curious)

[te51levin]

Very interesting. Didn't know the IO used mechanical injection.

The RV-7 looks pretty cool. I don't know an awful lot about aircraft, though I occasionally torture myself with daydreams of a Corvair-powered Sonex or similar. But then I also daydream about ever being able to retire. Anyway, I understand the desire for redundancy and staged implementation.

You may find some relevant conversations at the forums. Try MSEFI (now read-only, but still a resource) and msextra.com - I think those are the biggest two.

[emsvitil [OP]]

I've found msextra.com.

It's just getting the correct search terms so I can find what I'm looking for...…………………………...


thanks

[te51levin]

Learning the language can be a little tricky.  It might be easier to start at the other end, so to speak, and see what different users have done to configure MS on a piston engine in an aircraft.

There are plenty of results on a Google search for 'megasquirt Lycoming', so maybe some of them will be beneficial.  Probably have to shuffle through the forums to get more detailed information.

You might also try shooting an email to the people at DIYautotune.  They were, and I assume still are, the default source for all things MegaSquirt.  If they can't answer your questions they can probably at least point you toward a better resource.

Sorry I couldn't be more useful.  Good luck with the project.  It sounds like a fine way to spend your time.