I'm in the process of trying to "hack" several old NipponDenso automotive fuel injection computers. I am pretty sure that the ones I am currently working on are both 8051-based.

Hardware hacks are not my speciality, so I thought I would ask here whether there is someone who might be able to devote a little time to helping me with my project. First step is to read out all the "map" data and runtime code from these units; I had someone think one of the units contained an 8048-class MPU, but could not locate any runtime code (I suspect this is because it is actually an 8051-based MPU).

Once I have a clear block diagram of the hardware and have decompiled the runtime, I intend to make some changes in the runtime for both units, and hope to piggyback a daughterboard in place of the original MPU. The daughterboard would give me real-time ROM "emulator" capability from a laptop (USB would be the preferable interface), the ability to edit/rewrite the "maps" (which would be in an outboard EEPROM that I could write values to, ideally, while the MPU was operating), and the ability to provide data from the inputs (fuel injection sensors) in real-time (observing the ECU's inputs, and potentially data-logging them).

Any assistance, however small, would be welcome. I will eventually be providing modified ECUs to people who own these older vehicles, if everything goes according to plan, but I only intend to charge enough to recoup my costs in developing the mods and adding them to existing ECUs, as an enthusiast endeavor rather than a serious for-profit business. I will be happy to share whatever I earn on "sales", or alternately would be willing to pay someone a reasonable sum to help out with development.

Any and all assistance, ideas, suggestions, etc. gladly accepted!