the yj computer can not be reprogrammed or reflashed if it be a dealer or a tuner. the chip that is in the computer is an eprom and located under the gel in the computer the chip requires the gel to be removes the chip to be un soldered and a new flasable chip soldered in. after that nobody has wrote the code to be-able to read the chip meaning that even if you put a new chip in you would not know what to put on it.
i have done a lot of research on the subject of tuning a yj or any obd 1 jeep
All we can do is upload new software onto the vehicle that we download from DealerConnect. The only things we can change is simple stuff like horn beep when doors lock. We can't just go in and change different tuning parameters.
Edit: And good luck finding a dealer that still has a working DRB2 with a Jeep adapter. You're best off going to a independent tuner.
1990 YJ-The wheeler
2015 JK- The DD
100% No. I did a lot of testing with the OBDI in development. It is not flashable, that being said there are other options you can use to trick it into thinking differently. Wideband O2 sensors, adjustable map sensors, and even relocating the crank sensor to change advance and allow for bigger cams. The question is at that point why would you. There are other options available and unless you are stroking a 4.0L it is a waste of money and effort. You would be fiurther ahead getting a 350 with the effort you would need to use to do any of the serious tuning.
There are people/companies that have hacked the SBECII ecm and made it tuneable, however its mainly on other mopar cars. There was a guy at one time working on a jeep specific definition for the bin on the chip (that has to be dug out of the gel, de-soldered from the board, then read. However I think they lost interest in it.
If interested, you might try contacting these guys and see if they have any suggestions. http://www.boostbutton.com/catalog/
'93 YJ 4.0L, AX-15, NP-231HD/SYE, 8.8in rear, OME 2.5 lift, WJ knuckle/brake conversion, hydroboost. Warn M10000 winch. Hope to some day build a stroker for it.
'79 Cherokee Chief, 401 MPFI fuel injection, T-18/D-20 and hydroboost. Otherwise stock.
Future mods: NV4500, NP205, high pinion D60 front and smooth bottom D60 rear, e-lockers front & rear. SOA with 35X12.50's