[Richard22]

I compared an aftermarket chip to a stock chip for rev limit. F0 was changed to DE. This changed 6500 rev limit to 7000.

All the differences in code are accounted for except this. In another area, D2 was changed to C2. Is this change also rev limit related. Any ideas?

 

[Tifosi]

Stock chip and aftermarket chip for _____ with _____ EFI system?

 

[CorseChris]

I had a fiddle with the chip in an old Lucas system a few years back. I was fiddling with fuelling mainly, but any changes made to numbers like that, changed the checksum, which required a change to the checksum correction bytes....so I suspect this is what you are seeing.