Problem with VR V8 Auto memcal

[Charlescrown]

I have a VR V8 auto and can put the hsv program into the memcal but if I change any of the maps eg ignition timing and reload it into the memcal the car is in limp mode. Put the unmodified program back in and its fine. Is there a starting address when writing the program to the memcal?
Any help appreciated.

[festy]

Is it a checksum issue?

[Holden202T]

sounds like you need to bypass the checksum

[Charlescrown]

How do I do that?

[Jayme]

set the "program ID" near the top of the constant list to AA, that will tell it to ignore the checksum.

[charlay86]

There should be an item in the XDF called "Engine Program ID - $11=VR - $AA=bypass checksum"
Change it from 0x11 to 0xAA

[antus]

Added to the faq:

"Im working with a factory program, and if I run the factory bin as is, the car runs, but if I change something and try to start it, then its a no start. What might this be?"

https://pcmhacking.net/forums/viewtopic.php?f=7&t=1396

[Charlescrown]

OK I have changed the XDF file line 3 020011 DescSize = 0xAA. It was 0x1.
I hope I am doing the right thing.
Whats next?

[Charlescrown]

Not sure if I was supposed to actually change the XDF. I can see the program ID but I can only change it to a number.

[VL400]

Nah leave the XDF item as 0x01, if you cant change the item to 0xAA make it 170 (0xAA is a hex number, 170 is the decimal equiv). Its likely that the XDF item is not defined as a hex item so cant use any letters.