Originally Posted by
turbo_neoffroad
hi, guys.. just registered after following this whole JTEC reprogramming thread.. it sucks to see that good progress came to a grinding halt..
hopefully, i just may be able to help and get this show back on the road...
i noticed that the JTEC wiki isn't working - except for links to a couple pictures..
so, hopefully between here and speedfreaks, this can get worked out..
as far as this SCT company, it looks like they're just flashing calibrations, rather than the whole eeprom..
does anyone know if the pinout for this motorola z3 processor exists (or as least for this processors' maskset)
need to find out if this eeprom has the programming voltage and reset pins going to the processor.
(can we just get the eeprom to drop into programming, or does it need to be bootstrapped like the motorola ME7 / 7.2 / 7.5 ecus?)
i know a lot of the newer chrysler pcms' use that SCI bus specifically for programming - not sure if the older ones even have that bus...
so, if we have a pinout of the processor that's in there, and if the correct programming pins go from the eeprom to the processor, it's just a matter of finding all the calls to the port that controls those pins, and working backwards from there.
usually for 'security', a lot of these obdii programmable pcm / ecu's will use some completely screwed up sequence of commands to enter a programming mode..
GM uses a seed / key for security access
Subaru uses a pin that goes to B+ voltage
volvo actually uses the central electrical module to do all the dirty work - it puts all the modules in the car into a 'bootstrap' mode, all the data is sent to the CEM; which then decides if the data is good / checksummed correctly, then it will program the corresponding module, then reset all the modules in the car to take them out of 'bootstrap'
(BTW - you can just bootstrap the eeprom in a volvo ECU, and directly read / write to the ECU via a basic K-line connection)
The older nissan JTEC ecu's had commands you could send via diag line to read out the ecu - one byte at a time
I guess one obvious way to make this easier would be to record the argument between the PCM and a J2534 during a standard calibration update.
The maps, axis, and scaling information is a pretty straightforward thing to do. I don't understand some of these other posts by 'those in the know' about the stock PCM not having the 'resolution' to do this or that...
part of the formula that the pcm / ecu uses to calculate how long to fire the injectors is 'injector deadtime' - this is the value you use to change the size of the injector - you change that, and everything else on the fuel side gets scaled accordingly.
using a stock pcm / ecu, you actually have a very good amount of adjustment (plus all the factory safeguards) - oh, and for those with OBDII, when inspection time comes ALL the OBDII test calibration stuff is in there too... hell you can set it to run all your monitors at idle, in 5 minutes if you want.
I am completely hellbent on being able to reprogram this pcm....
it's a motorola processor - so BDM is a viable option - even to just 'watch' what the processor is doing
I understand (in a way) what the 'companies' are trying to do.. "I know something you don't know... unless you want to pay.." I understand they have overhead, development costs, marketing, and of course; since the only people who can really afford some of this 'tuning company' stuff, pretty much piss money, they need to make a hefty sum since only a few people will have enough money to buy...
Dilemma did a open-source project for SAABS - T5 suite, T7 suite and T8 Suite. sure, if you didn't have the technical knowledge to do it yourself, most of the higher-end cookie-cutter tunes from companies were between $120-$350. That is a much more realistic price for your average person to pay..
And, another reason this should be obtainable info - if the car companies have their way (a couple car companies are whining to congress) - vehicle pcm / ecu's may be soon covered under the DMCA....
if anyone has copies of the stuff that got posted to JTEC.INFO, it would be great to be able to get copies....
Even if this PCM needs to be bench-flashed with some type of harness, it really needs to be figured out!
I'm sick of having vehicles with ECU's that can't be screwed with! I just finished my Discovery I ecu.. there really was NO info on it out there - thankfully, it just used 2 socketed EPROMs..
Reply With Quote
Bookmarks