I think the issues they're referring to are with regard to making the PCM believe it's a Holden (which I have no intention of doing).

MPG estimates vary, but I generally hear 2-4 on this alone for GTOs.

Holden is GM's brand for Australia. Mostly nice rear-wheel-drive cars that GM is to dumb to bring over here. The GTO is a rebadged left-hand-drive Holden Monaro.

 

from what I understand on HP Tuners the US version of their software restricts it flat out, but the Australian version allows it. Does Australia have the Silverado? If so would it have lean cruise enabled? (maybe not, hauling a load you wouldn't want it to be too lean) Either way from what HP Tuners says, their software has the capability, but b/c of US law they have it blocked.. maybe you can get your hands on an Aussie version?

 

Thats because with the aussie version all you need to do is edit the table values. The function is already turned on from the factory. With a US pcm you would need to not only edit the values but enable the function in the pcm code as well which is what he is talking about.

 

Not taboo at all. In fact, I encourage good quality talk about any tuning, as long as it isn't non sponsor popping. Personally, I'm not a fan of the leghumping that goes on so much here, but that's just me.

I'd be VERY interested in doing this. If my truck were even running, I'd be more than willing to send you a file to try it out on. (I use HPTuners). I can try and send you something later on if you like.

For what it's worth, I have tried to edit the tables and can do so, but they are completely ineffective. It doesn't matter what the value of them are, they do nothing.

 

Guys, if you go EFI commerical and can load custom OS #3 (and others), you don't need to edit the OS code at all. COS#3 is an SD OS, but has the ability to target a particular AFR via MAP + RPM, so you can build your own lean cruise with a few minutes of work. I've been running this way for about a year (as have others) with no OS hacking.

I just found the cruise cells and idle cells and target 15.7 AFR in those cells. Because its MAP targeted, you don't have to worry about hitting this AFR unexpectedly.

 

That is the one reason that makes me wish I would have gone with EFI instead of HPT, but nooo you had to go and give me a deal and sell me your HPT.

 

Would it make sense to run one of these custom OSes with a nearly stock truck? Tuning is essentially the first performance mod I'm doing to my truck, hopefully followed by electric fans and a cat back.

 

Wanted to elaborate a bit on what I'm specifically looking at here...

This is the lean cruise skipping code. It just jumps over the execution of the lean cruise subroutine.

(I obtained this code from http://efiforum.iqd.co.nz/showthread.php?t=833)

To remedy this, the line "bne.s loc_0_29A96" would be changed to "nop" for no-operation. I believe this could easily be done in the binary file as the bne.s is two bytes of machine code, as is the nop opcode.

The binary version of the above code looks likes this:

The updated version would become:

I used the "EASy68K" 68000 Assembler/Simulator to figure out the above (www.monroeccc.edu/ckelly/EASy68K.htm). My assembly is quite rusty and I've never written assembly for this particular chip, but everything appears to check out.

Also note, the "--" parts are memory addresses, and thus are unknown as the code is not necessarily in the same place on different PCMs.

I downloaded a stock 04 Silverado 5.3 PCM BIN file from this site:
http://www.horist.com/hptuner/

and searching using a binary hex editor the above code sequence is present.

That's where I stand at present on this. Now I need to figure out a way to get my raw BIN file off the PCM, and then get a modified version back on the PCM. I read somewhere there are also checksums that must calculated for the updated BIN file or the PCM will reject it...still have no idea how to calculate/insert those.

Again, I don't actually have any tuning software yet other than a demo version of EFILive (obviously with no interface). Want to have this figured out before I spend the money as it might influence which software I buy.

 

PM me and I can put you in touch with someone who can enable lean-cruise for a small charge....he's a member on 'Tech but he's not a sponsor so I don't want his name floating around

 

Anyone know if HPT will allow a .bin to be written to the pcm with the above changes made to it? I really hate to pay for something that I have already paid over $700 for the ability to do it myself....