Hi,

i'm just wondering if i could get a list of the various tuning maps available, and also their respective resolutions. i think i know them, just want to get an official listing. maybe others are interested also.

oh, this would be for the v2.2 or v3 board, running ignition control also.

thanks

 

did a little reading on the megasquirt info site, and found the following:

The most fundamental parameters are in the
- 12×12 volumetric efficiency (VE) table(s),
- the 12×12 air/fuel ratio (AFR) table(s),
- and the 12×12 spark advance table.

is ignition split on the rotary also 12 x 12?

so you can use multiple tables for VE and AFR? how many tables and what would be the application?


and is there a way of increasing the resolution? i know 12 x 12 should be good enough for most purposes, but most current EMSs out there use at least a 16 x 16 map.

 

12x12 VE
8x8 AFR
12x12 Spark
6x6 ignition split

None of them can be made bigger.

The EMS's with 16x16 maps don't interpolate between rpm/MAP bins, nor do they let you set what each bin is... at least that's my impression. The Megasquirt lets you set each of the RPM/MAP bins to what you want them to be, and then interpolates when it's between bins. Because of this, 12x12 for fuel and spark are more than enough, as are the 8x8 AFR and 6x6 split.

There is also the dual table code, which lets you control the primary and secondary injectors by giving each set its own table. Using that code it's possible to get a VERY good tune, but it's also a bit harder to tune than using a single table and the staged injection code.

The AFR table is just used in closed-loop mode with a wideband O2 controller. The MS will modify the amount of fuel being injected from the VE table to match the AFR at the same point in the AFR map. If you using autotune in megatune, and your settings are set right, you'll be able to sit there and watch megatune tune your VE table using your AFR table, and it'll do it for you.

You can also switch between 2 sets of tables for VE and Spark at least, and maybe AFR (not split though) using an extra circuit with a toggle switch.

Last there are several smaller "tables" which are all 2 wide for things like cranking pulse-width, after-start enrichment, warmup enrichment, accel enrichment. For the warmup/cranking/after-start settings, you set several coolant temperature points, and set pulse-width/percentage values that correspond to each coolant temperature point. For accel enrichment, you specify either TPS or MAP based accel enrichment, and then specify the rate of accel, and a pulse-width to add to the calculated (based on the VE table etc...) pulse-width... this is used so quick taps on the throttle don't make the engine go lean and stutter before the megasquirt catches up and adds the right amt of fuel for the new throttle position.

 

Can you use 2 separate "switchable fuel maps"(with hardware fix) if you use renns's stagged injector code in MS'nS-E?

 

You should be able to, although I'm not sure if anyone has tried it or not.

 

ok, thanks for all that info.

i realize now that what you mentioned is based off the Megasquirt-I, using msns-e?
so we are not able to use Megasquirt-II hardware and software yet on the rotary?

thanks
- Aaron

 

correct. The MS2 doesn't have support for rotary trailing ignition yet....

You could probably do the "modify your CAS to have 4 teeth and use an HEI module" method to get ignition with MS2 working for leading only on a rotary... but then you'd have to use dual table code to tune, and it'd probably be a bit difficult for a first tune to use dual table code.

msns-extra has all the features such as the ability to use the stock CAS and ignitors/coils for leading and trailing, ability to control the idle speed using the BAC valve, staged injection using a single VE table, etc....

once I'm done testing the rx8 code, I'm going to pick back up on my port of msns-extra to the ms2 chip (if it's even possible with that hardware)... so I'll keep anyone who wants to know progress up to date... it's going to be a month or two before I have anything worth showing anyone though.

 

i'm anticipating your updates
i am not planning to put in a standalone EMS until my car gets back on the road, which will be in April/May. definetly leaning towards the MS. building it is not a problem, that is totally my field. just want to make sure it will do what i need it to.

so my only concern is that the specs for the MS-I look rather, well, archaic. i mean it is more along the lines of technology from the 80s, lol.
in fact the stock S5 CPU is more powerful

the MS-II looks like a good improvement, so i'm just wondering if msns-e gives basically the same functionality, where is the difference?

 

although the ms1 chip is a bit old, it performs just fine. It has a TON more features than the MS2 software wise right now too:

http://megasquirt.sourceforge.net/extra/index.html

Some of what it can do isn't even listed there.

The ms2 mainly at this point gives you more accuracy. Things like 100x the fuel injection resolution (so instead of a pulse-width being 10.1 ms, it's 10.103 ms ). There are other features but I'm not going to go over them here... just check out the MS2 page at www.megasquirt.info.

the ms1 chip running msns-extra works great, so it doesn't really matter to me how old it is... On tofuball's car we've got it running leading+trailing ignition using all stock components, fuel, opening the VDI and AUX ports, controlling an electric radiator fan, taking input from a techedge wideband O2 controller and using it to run closed loop everywhere but idle using an AFR table. Basically there's no real reason not to use the msns-extra firmware on a MS1.

I and a few others are working on porting those features to the MS2, but the MS2 has some limitations that the MS1 didn't... it appears to have fewer outputs for one... So it might not be possible to do some of what the msns-extra firmware on the ms1 can do. Bowling & Grippo (the designers of the megasquirt hardware) are working on a CAN bus router board for the ms2... basically the ms2 communicates digitally over a "network" to a router board... the inputs and outputs to/from the engine go to the router board, and the running parameters and such are comunicated to the router board by the ms2 over CAN bus. With this, supposedly all the msns-extra features could be supported, and then some... things like sequential injection for example... Of course using the router board will likely double the price of a megasquirt system...

Anyway, my opinion is that if the msns-extra firmware on an MS1 chip will do what you want... then stick with it... the fact that it's an old chip isn't a good reason not to use it. Even if the stock hardware on the stock ECU is better, tofuball's s5 'vert runs better on the MS than it ever did stock... and we're not even done tuning it.

 

ok muythaibxr, exactly what i was looking for, thanks.
glad to see there is a lot of functionality being provided by msns-e.

i'd like to hear what sort of work needs to be done to port everything over to MS-II.
i'm currently in university for computer engineering, in my 3rd year, so MS really interests me from a learning perspective. it would be great even to help on some of the development, although i'm not too good with software sometimes, lol. give me a PM if you need some (basic) help or something

 

If you have any project courses talk to your professor about doing some of the development for credit. MS-II is C, MS-I is assembly, so you've got two options. Might as well kill 2 birds with one stone if you have the chance!

 

awesome, i have my year-long project coming up next year
it would be cool to do that, however computer engineering projects are usually in a group of a few students, so i would have to get both cooperation and approval from the supervising prof.
maybe as an extra thesis credit or something? i'll have to find out...


on another note my university just started doing Formula SAE again, and i am in the electronics and instrumentation team. we are definetly considering using Megasquirt for our car, so that would be even more involvment with it for me.