Learning to read and modify hex and build cax files

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,735
804
113
Texas!!!
Who here has played around with this? I've been playing with EFILive on our trucks for years, but I have never ventured outside what is available from EFILive. As things have changed over the years, it seems EFILive has become less concerned with the average end user and focuses their support more on big tuning shops who can somewhat fend for themselves on some of the smaller issues that tend to crop up such as missing or mislabeled/inoperative tables that can be fixed or remedied with a cax file. I have never attempted to dive into that aspect of tuning, but it seems that if I want to continue this and be able to make the trucks do what I want, I will have to learn. Can anyone provide me with some tips and/or resources to start learning? What software do you use to to hex editing, and how do you figure out how tables are linked and what they do? I just don't know where to start here.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,743
5,911
113
Phoenix Az
Who here has played around with this? I've been playing with EFILive on our trucks for years, but I have never ventured outside what is available from EFILive. As things have changed over the years, it seems EFILive has become less concerned with the average end user and focuses their support more on big tuning shops who can somewhat fend for themselves on some of the smaller issues that tend to crop up such as missing or mislabeled/inoperative tables that can be fixed or remedied with a cax file. I have never attempted to dive into that aspect of tuning, but it seems that if I want to continue this and be able to make the trucks do what I want, I will have to learn. Can anyone provide me with some tips and/or resources to start learning? What software do you use to to hex editing, and how do you figure out how tables are linked and what they do? I just don't know where to start here.



You might get in contact with tony. Pretty sure he can help with atleast some of that.
 

N2BRK

Well-known member
Dec 31, 2009
2,059
391
83
great thread! I've used cax files provided to me for my truck, but would love to learn more and to learn how to go through the truck's ECM/TCM to look/find/modify things on my own. It may be a lot for a non-pro like me to handle though, LOL
 

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,214
364
83
At Da Beach
I thought there were classes for this somewhere, not for the EFI side but for people learning to write for manufactures. All I know is it's a freaking puzzle.
 

2004LB7

Super Moderator
Staff member
Dec 15, 2010
7,106
2,208
113
Norcal
Many years ago I tried to get my hands wet with HEX editing but it was way over my head. I was using Winols and trying to edit my VW TDI. From my recollection it gave you a sort of 2d graph of the HEX and I think you used this to find tables. Then you can highlight the area of HEX and see the graph (maybe in 3D?). Then you can lable it and bookmark the table.

I think from this you can find the address and then put this into efi live. How you determine what it does I have no clue. Maybe based on the values in the table you make an educated guess

Its been many years since I have done anything with it
 

1FastBrick

Well-known member
Dec 1, 2016
2,600
1,117
113
Junkyard
I really like this topic and wish there was more information out there.

I looked into it a bit on the gas side but wasn't never able to get any specifics from any one. I even tried getting a few people on board that supposedly had experience writing CAX files. Trying to get them to look for certain existing un mapped tables on the commercial side. Even tried bribing someone at an OEM with OEM Access to not only the calibrations but experience with writing the code in C++.

I forget the Program I was told to look into but it was like 10K. I would Drop that in a heartbeat if I understood how to use it.

The Diesel side seems even more Secretive. I understand wanting to protect your work But I just cant run a locked tune on my stuff. I will pay 2x the price and sign an NDA not to have a locked tune on my truck.
 

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,214
364
83
At Da Beach
Jesse Bubb offers classes, but they are very expensive for the non-commercial user.

That's what I understood, but it's been years since I looked into it. I was hoping the price point would drop as the manufactures move into electrics and less are learning to write files for combustion ignition but it may all be the same format. I know zero about the electric vehicles.
 

rcr1978

Active member
Apr 1, 2007
790
26
28
Spring Creek, NV
This is were I was at in my hunt just never did anything yet since I had no need yet.
Get yourself a spare ecm, china alientech, do some searching on boot pin tools and boot pin locations, read out the stock bin file with the alientech.

Make some small changes in efi live to a stock file and flash your spare ecm.
Dig out your alientech and boot pin shit and read out your bin file again then compare the stock/modified files in winols to find addresses/tables, this may help you get a general grasp on how to find the tables we have access to already, now finding the ones we don't have access to good luck :D

Not saying this is how to do it but this is were I ended up in my searching.
 

DPC

Member
Jan 2, 2012
323
1
18
Adams, TN
I have been wondering this same thing. HPtuner also gives you the ability to modify files with TunerPro and the "user defined parameters" but you have to know how to find the different addresses in the .bin file. I have no clue on where to start. I would love to be able to map out a .bin file for the L5P...
 

rcr1978

Active member
Apr 1, 2007
790
26
28
Spring Creek, NV
Did you spend the $$$$ for your 2018 and get the ECM unlocked? Hows the mapped definitions for HPtuners looking? I've been contemplating buying the software to see since you can't open a L5P file in the demo software.
 

DPC

Member
Jan 2, 2012
323
1
18
Adams, TN
Did you spend the $$$$ for your 2018 and get the ECM unlocked? Hows the mapped definitions for HPtuners looking? I've been contemplating buying the software to see since you can't open a L5P file in the demo software.

ECM/TCM unlocked. Very happy with the HPtuner stuff so far. If you have any questions send me a PM don't want to hijack this thread. Thanks.