aaronc7

Last digit of the OS is different between the GTO and 04 C5 file. -604 won't work on the corvette.

This is EFILive format, but this file claims to have the table definition to enable lean cruise on the -603 OS. No idea if it actually works or not.

https://forum.efilive.com/showthread...X-for-12587603

I think lean cruise is a little dubious on a car that doesn't have a wideband but that's just me.

Speedy007

Some guy is asking about post #13 what file was mentioned?

Nosferatu333

Op deserves a merit badge. Thank for posting and all the hard work. looks like I’m going this route.

aaronc7

Hey guys, a bit of an update. I've kinda migrated over to HP tuners over the past year or so. So I have a new zip in the first post with FF enabled files for Base A4, Base M6 and Z06 M6.

Also included a much more complete XDF for use with hptuners, to include tables like cranking fuel, fuel impact factor, evaporation time and stomp compensation. Plus all the FF stuff of course.

In my example files, I put reasonable values in all of these tables, but if you have user defined parameters, feel free to take a look and fine tune further.

Many of those tables are defined in EFI Live but not hp tuners. Also I discovered today that HPtuners removed the master EGR enable/disable switch... thinking about going back to EFI Live primary but not decided yet!

EGR switch is also in the xdf....

TastyBacon

aaronc7, big thanks for doing this. I swapped my '99 to an '04 Silverado PCM and enabled flexfuel using your XDFs earlier this summer. Looking forward to adding the new stuff in the spring. Shame on HPT for abandoning these older PCMs even though they're still extremely popular.

Thanks also to NSFW for making PCM Hammer, which allowed me to load the C5 -603 OS and change the VIN before reading the tune and licensing it with HP Tuners. Saved me from having to buy credits for the Silverado OS that I was going to overwrite anyway, and allowed me to create a VIN/OS combo that HPT would never allow.

aaronc7

Happy to help and share info. There's always been this mystic black magic cloud around flex fuel on Gen3, especially for the Corvettes since you generally don't want to do a segment swap to keep everything functioning correctly etc. And the only reason it's black magic is because both EFI and HPT never defined a few FF tables. I don't think many were interested in flex fuel/E85 for performance back in early 2000s I guess. People make it out to be like it's some custom logic or something really amazing....it's not.

Jonathan Eme

I tried to install the tune, and its requiring a new license, is that normal? I changed the VIN and it still won't install.

aaronc7

Hmm, yeah probably just a silly thing about how HPT does their licensing which is based off the controller serial I believe. When I first made this post I was still primarily using EFILive which doesnt have this issue. PM me and I'll activate it on your file if you'd like. Otherwise you'll probably need to buy user defined parameters so you can open the XDFs posted.

Jonathan Eme

tune attached

Jonathan Eme

I just want to publicly thank Aaron, because without his help, I would not have been able to fix my issues. He was instrumental in getting my E85 capabilities realized.

smitty2919

Is all of this info still valid? I'm beginning my journey on getting an early 03 C5Z (with early style fuel system) converted to E85.

Cliff notes:
My car has a P01 ECU. Source a P59 ECU
Need to re-pin my red harness and modify it or buy green connector
Wire in the sensor to +12/Ground/ECU
Use a 04 C5Z OS and simply enable E85? (with associated value changes) Or do the 04Z OS with spliced in 04 Tahoe FF segments?

This could be the latest most concise info in one place!

aaronc7

Yeah, that's it. I think early 2003 is same PCM wiring as mine (late 2003). You just run a straight 04 C5Z file. No segment swapping, everything works 100%.

If you need help getting flex fuel activated on the tune just shoot me a message, be happy to help.

smitty2919

Awesome. Good to hear!

Anything particular to look for when sourcing a P59 ECU? Does it matter what car/truck it comes from...where said car/truck was E85 capable or not?

Supercharged111

You have EFILive, right?

Edit: disregard, this is different from the other thread Smitty bumped. Gonna give this whole thing a reread.

Supercharged111

So the multipliers and stuff that EFILive/HPT didn't unlock aren't zeroed out on a stock 04 C5Z tune? Mine just happens to be an 04 C5Z. The xdf won't work for EFILive (far as I know) but cax files do.

​​​​​

Tusc

Uh oh. Smitty's going on the rampage now. Welcome to the early stages of the snowball project effect.

aaronc7

Get the part / service number in the first post. I believe there's another couple PN that may work. I can't recall the details, but a few websites out there cover which PCM PNs support various HW features (like electronic throttle) etc.

I have both EFI and HPT now. The XDF will work with HPT but you need to purchase "user defined parameter" access. There is also a CAX file in the original post which will work with EFILive. Will have to convert it to a CAX8 I think if you're using V8 software. Honestly I prefer EFILive and think the definition files are a bit better too, on these cars.

And yeah, there's a slew of flex fuel related tables that aren't defined in HPT or EFI and those are zeroed out basically in the stock 04 C5Z tune. So it's just a matter of populating those (and a few others like the E content vs stoich table) to get flex fuel working.

smitty2919

Ported heads and E85 has been the plan for a while. Ported heads is the easy part lol.

Thank You

Supercharged111

I knew I should have gone back and re-reread that first post last night. I see now it was all wrapped up in the zip file, one stop shopping. Mine came to me with 12592425, based on what you were saying about the difference between the 2 OSs, I could likely rename that .cax and it would work for my OS? I searched the cax text file for the OS number and didn't see it embedded in there. I also have a completely untainted version of 12592425 if you like. It sounded like you already had one, but you didn't have an EFILive tune in there ready to go with the FF already enabled. This and lean cruise are the sorts of things I'd prefer to have in place before slamming a COS on top. BTW, as it pertains to the P01, the lean burn stuff is even easier than this to get working.

aaronc7

Yep, just rename the -7603 CAX file to 12592425 and it will work. That OS upgrade was just a few minor fixes IIRC, but the file structure is all the same.

Let me know if you need any help getting your file FF enabled, I can send you a file or two to diff.