ECU Maps

5th January 2008



The ECU has a number of Look Up Tables (Maps) that are used to determine the values of various functions. I wrote down the every address in the data section that was indexed in the main code and then used TunerPro as analyse the data. These are some of the tables that I found. The EEPROM is mapped from address 8000h so the address shown in the code must have 8000h added to it to give the actual address, ie. 10C0 is actually 90C0.




This appears to be a fuel map, the fuel map will roughly follow the shape of the torque curve. There appear to be two fuel maps the second is shown below. This line of code selects one or the other:
D49B     87 D7 20 03       brset     L00D7, #$20, LD4A2



I suspect that the map below may be the ignition map. If you took slices through it it would have the same shape as the advance curve that a set of points would give. Flat for a bit (around idle?), rising sharply then levelling out. I'm not convinced by this though. I would have expected something more progressive from a digital system. I may model this in EXCEL so I can spin it round and get a better view of it.



Alternatively this may be the ignition map. More datalogging is required before I started playing with values.