Following the engine build and immediately recognizing the need to get the modified car and its computer playing along together would result in a far less explodey disposition, in early 2019 i set about finding the way to tune Roxanne's Ancient flash tune computer using modern means. I sourced an ALDL USB connector cable from RedDevilRiver and immediately realized a problem: My desktop Battlestation computer was far too cumbersome to be used as a tuning machine! I looked around our apartment, Knowing The Wife had some old Laptops in storage I dug around and found a four year old, $249 Asus R3-131T running windows 8.1 with an unusably dead battery. "No issue there" I figured, as i could a power inverter with the cigarette lighter plug to keep the thing alive while i logged data and worked out my tune.
Not so. Every time i cycled power to the car, i would lose the datalog. So the first order of business in restoring this machine to a usable state was to replace the battery. After fixing that Gaffe, I installed EEhack and Tunerpro RT, Then began teaching myself what little i could about those programs. At the time, I knew very little about these flash tuning systems, or their inner workings, or how to adjust them. Eventually, i reached out on Fuckbook to the Roadkill fan group and had another fan and 3k hooptie challenge competitor take a look at and even help to establish a base tune.It is worth noting, however;
In order to understand what i did not before, i had to do a lot of reading, so to hopefully save you some of that headache, i am going to try and explain some or all of what was done using the R3-131T here.
The first thing you need to understand is that you are dealing with the proverbial old gods of computing. The 4 bit GM PCM of Roxanne's Era was designed in the mid 1980s and built using proven, off the shelf components known to resist moisture intrusion, heat, and intense vibration, and to acquire and transfer data at 8192 Baud.
This system was never meant to be modified by the end user, yet we are doing it anyway. Modifications of this nature should be understood as being done at the risk of the end user damaging or even destroying the hardware and data inside (also called "bricking" the PCM)
Despite familiar similarities in construction, use, and structure, the 4 bit system used in roxanne does not begin to touch the capabilities of later 16 bit systems such as the LS 411 PCM. To those of us who grew up in the Era dominated by the Windows PC, understanding the conventions,norms, and institutional knowledge of this era can be a daunting, even immobilizingly difficult challenge. For Starters, Rather than using later, the faster and more capable "SAE J1962" OBD-II or CAN-BUS protocols, the ALDL Link used by GM Powertrain Control Modules (Hereafter PCM) of the era is based on the old RS-232 communication protocol with the sigificant difference being that ALDL uses a pulse similar to 1 wire low pulse to establish value, rather than voltage in standard RS-232.
The GM LT1 ALDL PCM uses a pair of customized Motorola 6811 Processors running at 8.388mhz, with 2KB of Ram, a 32Kb UV EPROM for Calibration and Code, and a 128kb flash memory module. The final component of the PCM enclosure is a Piezoelectric knock module that is designed to retard timing if it detects knock from the two sensors located in the head. The two processors are used to record "Event" and "time" data which based on values set by the block of Eprom Chips GM called called MemCal,Short for Memory and Calibration, adjust timing and fuel curve based on atmospheric data from the Mass Air Flow (MAF) and Manifold Absolute Pressure (MAP) sensors, as well as readings from the oxygen sensors on each bank of the exhaust.
None of this matters if you cannot access the computer. In order to access the data stream being generated by the PCM in assembly language, It is necessary to use a program which can decode the 10 digit data packets sent by the PCM. For this task, i used and will continue to use eehack to log data and Tunerpro RTto make changes to the tune.
The R3-131T required a minimal amount of playing with to make work. The biggest hurdle was getting Visual Basic to understand what it was seeing coming in through the USB, And some minor tweaks were able to be made to the tune using the R3 including, but not limited to
The only major change made to roxanne during this time was that i found an example of the elusive and long discontinued LT4 Knock Module,installed it, and ran a singular tuning run to ensure improvement. although the timing retard run by the car was still present, the events of 2020,and my personal circumstances of being a horrifically underpaid retail employee with a target on my back in a market populated by the most ignorant fuckers on earth slowed the rate of my build and indeed any work done for personal reasons down to a crawl i am still recovering from today.
By Fall 2022, It was becoming increasingly obvious that the R3 could no longer hold its own as the mobile tuning machine it once was. Indeed, windows 8.1 had ended support, and the aging N3050 processor was having issues even maintaing an open browser. In spring of 2023, I elected to remove the Microsuck bloatware and see if the R3 would handle Linux as its primary operating system. And so began the nearly 2 month long ordeal of assembling eehack in a Linux Distro. With the help of a few friends in the IT field, I,
By august 2023, With the machine clearly on its last legs, I began scouring eBay for used IBM Lenovo Laptops to replace the R3.
I wanted something better than what i had,(a paperweight in need of replacement) and i know there are constantly commercial use or industrial use computers on the internet being sold as-is before they get dumped into
some gigantic e-waste pile. Digging around in a sea of utterly worthless google machines chromebooks, i found the deal of august 2023,a school or office used lenovo with an i7-7300U and 8gb of ram. Two years newer than the
R3 and nearly 4 times the price. TEven though it had come with a fresh Windows 10 Pro install, Immediately after unboxing the machine and verifying it worked, i shoved my Ventoy into the USB slot, Installed Arco-D on a dual boot, compiled
EEhack, and got to work at long last with a reliable, stable means to program the computer in roxanne.
