Tuning available for 93-95 L32 and L82 PCMs

[95cutlassproject]

turn the 4t60-e to 8k shift points! Well that wouldn't exactly do much other than make the tranny explode. Though if it was possible i think it would be nice to change a stored tune for like a 3k shift point that way my brother can't beat on the car to hard while he runs an errand in it.

[robertisaar]

i'm a liar...

final interesting piece of information i'll release today:

the only difference between the tunes of a 94-95 L82 L, N, or W body, and a 94-95 automatic or manual trans L32 F-body is in the calibrations....

cliffsnotes: the 94-95 3.4 automatic cars run a 4L60E.... meaning pressure control solenoid. so you can actually run a 4T45/4T65/4T80/4Whatever on the 94-95 3.4/automatic PCM, just have to setup the options in the tune to do so.

[robertisaar]

i don't even know what it's for yet....

also, last teaser for the day: VE tables(main and idle, no adder) in the tune are stored as 16 bit tables... the highest value in the stock tables is the decimal equivalent of 1,056...

if that last part makes no sense, think of it this way: if a stock 3100 requires 1,056 for a correct amount of fuel, and it's VE is somewhere around maybe 80 or 85%, and the maximum value possible is 65,535...... well let's just say that VE values beyond 100% are entirely possible to be stored without any trickery.

[95cutlassproject]

Surprises, i like surprises, i cant wait to see what can be done, somehow hearing 255 row 2D table make shivers run down my spine.

[robertisaar]

man, are you guys in for some surprises.... i've never seen/played with an OBD1 PCM other than the northstar PCM that uses some 16 bit 3D tables.....

i've never seen a 255 row 2D table until now either.

another interesting tidbit: it almost looks like GM left in the code to use a PCS equipped transmission in the FWD cars. not sure if the hardware is there though.

i'll shut up and get back to hacking now.

[madtuner]

I am glad to see there is some interest in this. I just had a few of these PCMs on my shelf for nearly a decade and finally decided to give them some TLC. As I mentioned before, I have already developed the software to fully read, upload, some datalogging (though this can be accomplished via Tunerpro already thanks to Robert's definitions) and I have mapped out quite a bit of code and variables. I expect to be able to tune them for any modifications in a couple of months with a little bit of help.

[tkoforpresident]

This could be interesting! Although a little late for me, as I already swapped to OBD1

x2 lol

[19Cutlass94]

This could be interesting! Although a little late for me, as I already swapped to OBD1

[95cutlassproject]

So many great things seem to be happening. We have the nAst1 progject, the custom intake(superchargers anyone) and now the possiblity of tunable obd 1.5 PCM this is going to be amazing!

[robertisaar]

considering mode 2 sends a total of 6 bytes(including checksum), and then recieves 64 bytes of RAM or ROM in a 68 byte packet(checksum included again), it's a fairly efficient and simple method. just have to increment the address by 64 bytes for every command until you get to the end of the PROM. since these PCMs use dul 32KB PROMs, it requires a total of 512 commands to grab all of the bytes from 1 PROM. takes about ~55 seconds per PROM IIRC.

[madtuner]

Interesting. I never even bothered to try that. I just wrote my own bootloader. Could have saved me a little bit of work. Will reply shortly.

[robertisaar]

you can dump BINs through the ALDL circuit, same way the 94-95 LT1 guys do... couple different methods to go about it actually, i believe mode 2 commands typically are fastest without sending a custom program over the ALDL that resides in memory and just continuously dumps the BINs(since there are 2 32KB PROMs to deal with).

don't suppose you have interest in the 93-95 NorthStar stuff as well?

[madtuner]

OK Robert, maybe we can combine efforts and add features quicker since I have so many other projects.

Please e-mail me at support@madtuner.com and I will send you a few bins. I have developed my own software from scratch, though I am curious what you mean by pulling it through the ALDL circuit.

[robertisaar]

i've never messed with the OBD1.5 native code, i've been too busy adding stuff to the $A1 mask.

i've never came across(nor had the ability to write) the software required to actually write the tune to the PCM, which has been my big hangup.... pulling it via the ALDL circuit is cake though.

if you could send a few BINs my way, i could probably run them through my disassembler though, just need to know which areas to focus on.

[madtuner]

Robert,

I take it you have modified your tune already at some point? Please let me know which parameters you have been able to uncover. I've got enough to tune most cars out there, but I am still missing a few parameters for more advanced modifications.

I have used your datalog definitions in the past by the way. Thanks.