Ramblings. Not all of this is accurate, and I've probably gone over myself a couple times.
So, to keep things relevant, only the plastic case ECUs can be reflashed. The metal case ECUs (to my knowledge) can only be read, and not written to.
To do so, you need a few things:
- Tactrix cable
- Reflash plug: this is a white plug located just above the OBD plug (often tied in with the loom), which is a single wire that goes to the ECU
- Software to flash (ecuflash is a very popular one, i think theres a couple others, but I'm not familiar with them)
- Wideband AFR sensor and gauge
- Plastic case ECU (i think it may be from 1998 onwards?)
Essentially, turn the car to ign, and plug in the tactrix to the laptop and to the OBD and reflash plug. Open up ECUFlash, and click read. Bam, you now have your ECU's ROM file.
The ROM is a "text" document of just hex code that your car's ECU reads to control fueling, timing, rev limit, and a couple other things ill get to below. ECUflash will use another file called definitions to decode this ROM and put it into something that we can read and modify.
Oh wow, this is amazing, I'm going to be able to do so much now!
Yeah nah, hang on a minute. The stock ECU doesn't allow for a whole lot of adjustability.
- You CAN change the injector size (to upgrade to larger injectors), but you need to know the flow rates, and then measure/add in latency (depending on battery voltage). I do not know the upper and lower limits you can input.
- You CAN change the AFR values, but keep in mind it may not respond the way you want it to without that wideband to confirm. I do not know the upper and lower limits you can input. Your fuel map is a 3D table: RPM v LOAD v AFR. From memory, your AFR ranges from 14.7:1~ to 11.6:1~ (ive muddled my stock map as practice, so i dont exactly remember) but remember your ECU's input for this is the stock narrowband o2 sensor, which has a range from like 15:1-14:1, so its not really accurate by a long stretch.
- You CAN change timing; map reads as 3D table again, RPM v LOAD v Degrees. I do not know the upper and lower limits you can input.
- You CAN change the Rev Limit; something higher around 7500 rpm may suit your fancy, providing your upgraded valve train can cope. This is a simple single cell to edit.
This is basically it for the stock ECU. No fancy launch control, no super duper dual mappings, or anything like that. Plain, simple, economic ECU like the car was designed for.