antus wrote:if the comms is just serial and you understand them, could you replace the control logic hardware completely but keep the electronic throttle assembly? run from a pro micro or something? obviously would be safety considerations in the implementation and not for road use.
definitely possible- and is essentially what some companies are doing... that are converting signals and splitting logic and what not. Me not being a hardware person I was on the assumption that a 'simple' retune would be best. I was hoping I would run across someone with experience in dumping and flashing these older chips. I have experience with JTAG but this is older than that. Also I'm only looking to make two changes to the programming, the max idle TPS and inverting one of the TPS ranges, so it just seems easier to reprogram vs all new.
I'd bet the process is super simple, just not well documented.
Would inverting one of the TPS ranges allow the use of Gen4 throttle bodies without the $200+ adapter?
exactly.
and if you could turn off current monitoring you could even run a cheap china gen4 TB.
and if you could turn off current monitoring you could even run a cheap china gen4 TB.
I'll be happy to take a look and see if there are any parameters that look at that in the Engine Diagnostics segment of the calibration, maybe changing the range would allow the GEN IV throttle bodies to work. I'm not very good outside of the calibration section, but I'm sure there is a way to turn off current monitoring in a similar way that Lean Cruise has been turned on (I believe by skipping the Holden verification) or like the A/C Logic patch has been added in order to use the pressure sensors on a P59 without the need for an HVAC module.
and if you could turn off current monitoring you could even run a cheap china gen4 TB.
I'll be happy to take a look and see if there are any parameters that look at that in the Engine Diagnostics segment of the calibration, maybe changing the range would allow the GEN IV throttle bodies to work. I'm not very good outside of the calibration section, but I'm sure there is a way to turn off current monitoring in a similar way that Lean Cruise has been turned on (I believe by skipping the Holden verification) or like the A/C Logic patch has been added in order to use the pressure sensors on a P59 without the need for an HVAC module.
this logic is handled within the TAC, not the PCM. We'll need read/flash capability of the TAC to make these changes.
Am working on reverse engineering tac and using a raspberry pi pico to replace pcm and allow tac to be used standalone. One thing I have learned is that the cpu used in the tac, a Fujitsu 6433038f, uses a rom mask. The code is etched in silicon, it has no ability to reflash. There are versions of these chips that have flash memory, but then you’re into setting up some kind of development without any vendor assistance. The pico is a much better route imo. Using factory tac, pedal, and throttle body, you get all the safety/redundancy features relating to throttle. You can also purchase any of these items at your local auto parts store.
The formats of tac/pcm messages are covered under J2178. They are type 3 read functions, 3 byte request, 6 byte response (+crc). This knowledge is not as comforting as it may seems since these functions notions are vendor defined, though there are standard encodings for things like tps and mph, so it does help a bit.
