custom codemasks...

[robertisaar]

i was checking out all of the stuff at code59 the other day and i've been kicking an idea around in my head for a few days, and i think i have it sane enough to be able to explain it a bit...

why can't we just make our own codemask? i see patches and the like for other masks that turn the VE table from like 8x10 to 16x23 or something crazy like that. so in that same train of thought i came up with: an entirely new codemask that is entirely mapped so we know what every function is, what all the tables do/ where they're located, be able to set options like lean cruise, egr diagnostics, any size of ve/spark tables, electronic tranny control, anything...

i would think we would need at least 2 versions though: 1 for SD and one for MAF systems, or maybe there could be a option in the definition to switch back and forth using the same mask.

if i knew how to do this myself i wouldn't ask, but i'm lost once people start talking about disassemblies and the like.

but from what i figure is whith the collective knowledge of everyone that knows how to write a codemask definition, this should be possible, right? i mean GM made a couple dozen codemasks using the same basic hardware, so why can't we?

by the way this is going to be up at w-body too, so i can help progress this idea faster.

[Guest]

The "code mask" or in Tuner Pro terms "XDF" is just a way of interpreting where the tables and constants are in the code (BIN) itself. You can do whatever you want to the mask, but it won't change the fact that the tables and parameters are set up by the BIN itself.

The code, AKA "BIN" is what you would need to write, essentially from scratch to do what you want to do.

I know I've seen this idea brought up over the years, and while it is possible, it would take quite probably years to write, test modify, test, re-write, test, test, test, before a reliable code could be released. Look at Mega Squirt for example, this is essentially what happened there, but they started with all new hardware as well.

Once you see just how much of an undertaking it would be to start from scratch, it doesn't seem to so bad to stay within the "confines" of existing code, and if need be add code or "patches" for extra functionality.

There is a lot of code in the BIN that won't be shown in a tuning program, since they are simply instruction lines that have no real user tuneable interaction.

There is a document that goes through the functionality of the Motorola processor that is used by the OBD1 GM ECMs, and it's long. I've started reading it, but it is very dry reading.

I'll post the link once I find it again. I think it's called the "Motorola Pink Book". You would have to understand exactly how all the address lines work in order to start from scratch, not something for a novice IMO.

[robertisaar]

you got exactly what i meant, my terminology backwards as it was. and megasquirt did come to mind while i was thinking about it but it has a few deficiencies that a factory ecm/pcm covers like malfuction checks/tranny controls/abs...

then the idea of megasquirt piggybacking a factory computer comes up but you still cant change the fact that you can't change fuel/spark maps the way i'm talking(making them much more precise). i mean look at DA code(DA2 or DA3 however its refered to) for the early LT1 motors, 2 VE maps(lower going from 400-2000 in 100rpm increments, upper going from 2000-7000 in steps between 200 and 500rpm), with 17 places for MAP and 29 for RPM. thats huge, but i bet it'll run better than most anything else(obd1) when properly tuned thanks to the very detailed maps.

and it is the pink book you're talking about i've heard it refrenced many times lately.

and on a slightly related note: how big are the fuel and spark tables for megasquirt, 12x12?

[Guest]

you got exactly what i meant, my terminology backwards as it was. and megasquirt did come to mind while i was thinking about it but it has a few deficiencies that a factory ecm/pcm covers like malfuction checks/tranny controls/abs...

Which is exactly why I DON'T use Mega Squirt in ANY of my conversions. I like some of the refinments that the OEM OBD1 GM ECM has to offer. I have a '7749 with $59 running my Nissan 2.8L I6 in my 1973 Datsun.

then the idea of megasquirt piggybacking a factory computer comes up but you still cant change the fact that you can't change fuel/spark maps the way i'm talking(making them much more precise). i mean look at DA code(DA2 or DA3 however its refered to) for the early LT1 motors, 2 VE maps(lower going from 400-2000 in 100rpm increments, upper going from 2000-7000 in steps between 200 and 500rpm), with 17 places for MAP and 29 for RPM. thats huge, but i bet it'll run better than most anything else(obd1) when properly tuned thanks to the very detailed maps.

I can't stand "piggy backs", especially when you end up with less features or abilities after adding the piggy back.

Most GM code as at least 2 VE table, infact I can't think of any GM code that doesn't. Some just use a main 3D VE table, along a 2D multiplier table. Others use a "closed throttle" and "open throttle" or "main" VE table. Both schemes have thier advantages and thier disadvantages. Personally I prefer a single VE map. I use the main (extended) VE table (F29x) found in $59, for both open and closed throttle duties. Code has been added to $59 to allow the use of F29x for both open and closed duties, if the proper flag is seleceted for doing so. For engines that run in the same cells for both cruise and idle using the F29c map might help there.

and it is the pink book you're talking about i've heard it refrenced many times lately.

It will help understanding the way the code works even if you don't end up writing new code.

and on a slightly related note: how big are the fuel and spark tables for megasquirt, 12x12?

Yes, but there are also 16x16 maps available too.

$59 has a 16x32 main VE table (F29x), which has way more adjustability than needed, really. $58 has a 9x9 1 BAR table, that uses a 11x1 multipler table that starts at 90KPA and goes to 190 KPA. So, you could in essence think of this as a combined table of 9x18 table (there's overlap at 90 and 100 KPA), due to the way the multiplier works with using the 100 KPA cells of the main VE table and multiplying by the proper cell in the multipler table.

Honestly, with the avialable code around, there's really no need to start fronm scratch.

$59 is great for force fed applications.

There is a code based on TPI code ($8D) called "S_AUJP" that is good for NA applications, though it hasn't been expanded in quite the same way $59 has.

I am working with the $59 developers on a straight 1 BAR $59, to get the WBO2 fueling control, the expanded fuel maps, and many of the other options and refinments $59 has to offer.

[robertisaar]

all good stuff to know...
and i didn't know about the S AUJP, but it sounds like something i could get interested in if i plan on doing anything related to a TPI motor.

honestly, i just want something to run my 95 monte on when i get around to doing a motor/manual tranny swap, with the possibility of boost. or just pulling the body/interior off of it and sticking it on the frame of a 78-87 monte and run a LS1/2/3/6/7/9.... with a 6 speed.

[Guest]

S_AUJP could be adapted to other engines too.

I've thought about ways to run an LSx on an OBD1 ECM, but it wouldn't exactly be easy, and possibly not cheap.

The biggest issue is the ignition. The COP ignition system is fired directly from the PCM, at least on later LSx's, I've heard earlier ones may have used a box between.

The two reliable options I have thought of are converting to a dizzy, probably a front mount belt drive dizzy, and then using a GM dizzy ignition module to interface with. I believe MSD makes this dizzy for the LSx.

The other and probably better option would be to use a DIS system from either a Northstar, or one of those 32 valve 'Vette engine, the build code eludes me right now. The later being an easier interface, since it uses a 7x low res reluctor wheel and single sensor just like the 660 and 2.0/2.2L OHV I4s, but are harder to find, or very expensive. The Northstar ignition is easier to find, but needs more sensors to work, including two crank sensors and a cam sensor, along with a very specific reluctor wheel to trigger it.
You would also lose sequalial injection, but I don't really see that as any great loss.