Is it possible for a tuner to remap or retune a 20v (either ST or BT) ECU?

Not with the OEM ECU.
There is an option to remap the OEM ECU but in that case you need some additional hardware.
I have a TOM's ECU for the 20V silvertop that uses such hardware. However, you need to have good knowledge of programming since there isn't any software available to the public.

Toyoloog wrote:Not with the OEM ECU.
There is an option to remap the OEM ECU but in that case you need some additional hardware.
I have a TOM's ECU for the 20V silvertop that uses such hardware. However, you need to have good knowledge of programming since there isn't any software available to the public.

What hardware is needed? I'm IT guy, so it might be usefull for me

For a start, you have to create a PCB that lets the MCU refer to external memory. this can be done by grounding some of the pins to put the MCU in external mode. Problem is, those pins are used for inputs so you will have to take that into account. Often this is solved using a FPGA or similar (although I have some ECU's that use discrete components instead).

Techtom is one of the suppliers of such hardware. The controller itself is very similar to the 8-bit Motorola 8600 MCU but with an unique instruction set. I have already extracted the program from a silvertop ECU, disassembling however, is a PITA.

Not familiar with a Motorola 8600 microprocessor.

Would that be instead a Motorola 6800 series variant, such as 6801, 6803, 6809, etc?
If so, its similar to what both GM and Chrysler used in the late 80s and early 90s.........

Very interesting info. Thanks buddy. I wasn't considering doing a tune myself but rather having a dyno tune. Probably would be easier and more tunable to go with a stand alone and an adapter harness in all honesty.

s24a wrote:Not familiar with a Motorola 8600 microprocessor.

Would that be instead a Motorola 6800 series variant, such as 6801, 6803, 6809, etc?

Uhhh indeed it is... Guess I was a bit too fast on the typing...

If you know or have a good idea of what the opcode map is for your 68xx variant controller, you can utilize a cross-platform disassembler to generate the code base that the micro was using.
IDA-Pro is a good example, although not the only one and some I think could even be freeware or shareware. There seems to be a pretty good number for the Motorola 68xx family of controllers.

I mention IDA-Pro disassembler as it allows you to "tune" the action of the disassembler if not all opcode instructions are known to iteratively generate a disassembly that can then be used as the basis of modifying for your own unique software that will run on the controller.

will the 4agze oem ecu work with a 20v blacktop?? thinking of turbocharging BT20v nd can't afford to go for standalone systems!!
Any help/advice would be greatly appreciated.