bad_monkey

Ok, that makes sense.

As far as ignition timing goes, is it possible to run a knock sensor in a similar manner?

Do you have a full stock ignition table with the AFM input vs RPM?

If not then if someone can provide me a hex dump of the appropriate motronic ROM I should be able to decode the full stock ignition table from there (with some help from the info at frwilk) Then what we need is a conversion factor between the flow measurement of the AFM and the pressure measurement of the MAP sensor.

Perhaps do some datalogging with both sensors and observe the relationship between the signals? Then we can substitute pressure for AFM flow at varying RPM.

Then you could set the microsquirt ignition to our new approximation of stock, and based on whatever octane you want to run advance the timing a bit, using a knock sensor or (insert your idea here)?

Once we have a really good base fuel and ignition map, then there's something to take to a tuning ace at the dyno (that maybe an interesting group buy!)...

Then we find out that there's room for tuning the NA after all, especially without the AFM, and all the Turbo guys sell them and buy NA's.

And when Alina comes back we tell him to install Microsquirt.

*ahem*

RobHeinl

Wow, that's a loaded post. I know that the MS can run Knocksense and can use the Knock Sensor that's found in the 944 turbo. Beyond that I know nothing about using Knock sensing but MS is definitely capable. There's at least one 951 MS'er that is using his Knock sensor.

Personally, I'm tempted to throw in an M90 supercharger once I get mine running. Think about it- with total control of fuel and spark we could handle a well intercooled low-boost setup quite well. Plus we have the option of running water injection w/ Megasquirt, I believe.

FYI- do NOT use an MS2 for stock ref sensors, it takes more modifications than it's worth. The daughtercard needs modified (resoldering surface-mount components...), VR2 circuitry needs to be implemented and other settings need tweeked

Raven951

i tried searching through megasquirt's tuning info, but i couldn't find it........ What is the tuning resolution?

bad_monkey

Ok, apologies for length again...

Raven, do you mean the fuel/timing map resolution? I'm taking a look at the MegaTune info, but you're right, it's hard to see what stepping the maps have. You'd assume that it would be significantly superior to the Motronic, and that the levels would have to be interpolated from the stock map to the MS map... This is where we need Justins input, as he's already been there...

RobHeinl - I think you may have been reading my mind re: superchargers. I was thinking that getting the NA to a solid state of tune might be Stage 1, and then moving to a supercharger for Stage 2. Again, all of this can be done for a lot less now that we can afford to tune the ECU... [and here in NZ a 951 is 2-3 times the price of base 944, so about $18k USD, so please no "Duh, buy a 951 cos everyone says so" flames!] (heh)

The M90 might be overkill in terms of the output it produces and the resultant resistance, especially for those of use with euro-spec static compression. Perhaps M45 or M62?

However, I too am interested in the idea of water/methanol to allow more boost with stock compression. We need as small a blower as possible while staying in the more efficient part of the map as much as reasonably possible...

The ultimate would be a blower/ECU map package - that would be a new lease of life for all the original-engine NA's... a cheaper alternative even than the ugly but tempting LS1...

theedge

From what I remember, on the Microsquirt the maps are 12x12 for fuel and timing. The bins are user configurable for both (you specify RPM and MAP value) and interpolate.

Raven951

12x12? wow, doesn't seem worth the time and/or money. especially when you can get the same tuning resolution with the Maxtronic/Maxtune AND it's plug and play.

kudos to you for taking on the task, though. we need more projects of this sort.

maybe microsquirt will have a better tuning resolution in the future.

RobHeinl

Like Theedge said- it interpolates which means it calculates the values between the 'bins'. You can see this in Megatune- the rounding between bins is represented by bin colors- hard to explain.

JustinL

Fair enough. Microsquirt is another option that is a stand alone ECU. It's not for everyone, but it does have some distinct advantages over any motronic based system. 1st and foremost is that it's MAP based allowing for the removal of the AFM and freeing up the intake. Also, this allows forced induction. The spark accuracy will be higher with microsquirt, because I don't think the motronic calculates every tooth on the ring gear. There is also much more flexibility in terms of injectors and ignition options, n2o, water injection... etc.

I agree, it's not as easy as plugging in a chip, but again stand alone is not something everyone wants or needs.

reno808

I am going to be looking INTO THIS VERY NICE WRITE UP. keep up with the good work. whats the difference between the mircosquirt and megasquirt?

theedge

More resolution isnt really needed. It interpolates between all the bins, it calculates the values. So if you have a bin at 2000 RPM and one at 2500 RPM, but your engine is running at 2300, its calculating the right value using data from 2000 and 2500 RPM bins... And if its a huge issue, I think theres a new feature allowing some of the tables can be combined to give 32x16 and such for the VE.

Plus theres things that Megasquirt can do that Maxtronic/MaxTune cant even begin to dream of....

http://www.msextra.com/ms2extra/

theedge

Mostly size and build. The Microsquirt uses SMD parts (surface mount) so its very small, costs a bit more and mostly prebuilt. Its hard to add things like COP to though. Its geared towards motorcycles, jetskis, etc but works fine for cars for basic installs.

MegaSquirts are bigger, and theres a board thats SMD that can be bought mostly prebuilt, or a version that you build. Theyre more suited to adding features to IMHO.

Other than that, they can use the same firmware, the differences are just hardware.

blown 944

little highjack


the m90 is the best choice out of the eatons . anything smaller is not enough. It is good for around 12 psi with any available pulley and more with a custom piece.

Justin, I am also subscribing to this and if I can get back on Alex 's good side I might be able to get some timing and fuel maps

bad_monkey

Good hijack :-) I was waiting for you to chime in there... I was hoping to pick your brains regarding mounting the supercharger anyhow...

By my calcs, with the 10.9:1 static CR on my '89 euro engine, a max boost of 12psi equates to an effective compression ratio of 19.80:1 (at sealevel). Did you run turbo pistons? I'm thinking that I'll need to run water/methanol at least at the top end of the rev range.

With regards to microsquirt versus anything else - I'm with Justin, even if it's not 100% plug and play (it's near!) it's cheap, efficient and you can use most of the stock sensors and eliminate the AFM.

Ultimately, it will be as simple as wiring the module to a DME plug, adding the MAP sensor and removing the AFM, and uploading the software. Turn the key and go... $500ish US for an improvement in power and driveability.

AKA the NA holy grail.

blown 944

I am using the 9.3 pistons in the 83. I know that Dally is using the euro pistons in his and he is around 8psi IIRC.

I haven't researched but I imagine there is a thicker head gasket that could bring it down some to allow for a little more boost. Ultimately turbo pistons and rods (or aftermarket) are the best choice but for mild applications NA stuff should sufice if good fuel is used. Fortunately I have E85 at my disposal and it makes all the difference in what I can do with both of my cars.

Just Pm me about the mounting

Caleb B

Hello Justin,

I've been in the process configuring/ building my megasquirt for my early 944 na.
I wondered if you’d had screenshots of the settings to use the stock VR speed and reference sensors?
and possibly a tune or data logs I could see?

I hope all is well and look forward to hearing from you!