Good 96 LT1 tuning is finally here!

Hey 96 owners -big news! if you still have your original LT1 PCM, after several years of work behind the scenes, the 96 PCM will finally have good tuning software like the '94s and '95s. This opens the door to quality, affordable mail order tuning, easier AIR pump deletes, speedometer recalibration, VATS delete, injector improvements, shifting changes and engine performance improvements. A small group of guys has been working on this since 2020, and we are now doing prototype testing. I expect the solution will be publicly available by Thanksgiving. I'll keep you posted once it's fully ready for release.

This is really big news because the only other available option is JET DST 14005 which hasn't been updated since like 2006 and is steaming pile of hot garbage. It's also like $500. This will be a fraction of that cost.

And yes, an optional add-on includes unbricking, which is accomplished by soldering some connectors onto the two PC boards inside the PCM case. It allows you to directly re-load the comms instructions to a bricked PCM and then it's flashable again; this can be done as many times as needed. It's a bit more involved due to the soldering, but way easier and more reliable than adding a socketed chip. More details to come. Stay tuned!

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Very interesting as I use a DST on my 9 RMW. I really haven't had any issues using it once I got through the learning curve. I can do all of the changes you list and have many, including a tune for the Ford injectors which I have but not installed and tested yet (true slacker here on this).

I do have one BIG question, though.

Did they fix (easy fix) the issue they have had all along in that the DST would not tune the Buicks? The DST wasn't setup to connect to Buick coded serial numbers or something.

I ran into this issue when I got mine and had actually bought a Caprice PCM to put in so I could program the Buick. I had also found a back door through a gut to contact the original programmer for the Tuner Cat tuner that the DST is now owned by Jet. He was great, super nice guy, and wrote a short update and sent it to me. He was also under contract with Jet for the DST stuff so he sent it to them also. Jet also sent me a copy, but they never added to the new units they were making.

A user on this forum had the same issue and I sent him the update and he got going.

I hope the group working on this has that information and put it in place.

I really like the idea of the brick recovery Will that unit work on the old DST or only their new one?

Cost of the stuff?

Yes, it will tune Buicks (my 96 RMW will probably be the test vehicle for that). This deficiency really shows why JET is so terrible, especially given that the original programmer so quickly fixed it.

I will say that apparently the '97 PCM firmware the developer started with is very different from the '96 firmware; so I can't say for sure when it'll be done.

This unbrick system is completely independent of JET DST. It currently works for the '96-97 PCMs and development is in work on the '94-95 PCMs.

Cost for the HW will be in the $100ish US range. Software will be donation-based; the definition file is mostly done with some of the OBD2 diagnostics in work.

Have been following this through a tuner on FB that I follow. Great stuff for OBD2 B Body owners. They will soon have the stuff us 1 owners have had for years.

I am the person booster helped last year. I have not done much yet. Please keep me in this loop.

Hi,
I read your article about the new 1996 RMW LT1 ECM fine tuning.
I would like to purchase this for my 1996 RMWs.
Please keep me posted.
Thanks,
Gary

Some updates, and Q&A from the ImpalaSSforum.com:

Will this be VIN-locked? Or can I use it on whichever '96-97 LT1s I want?
Yes, you can use this on whatever '96-97 vehicle you want, once it is supported. It will not be "VIN-Locked" as many tuners are. We have found that the '97 LT1 calibration is radically different in many ways, so it may take some time.

Can I damage a PCM while reading the calibration from it?
You can never damage one of these PCMs during a read. It's just querying the memory and sending it out on the data line.

How does one write a new calibration to the PCM? What are the dangers, like "bricking it"?
These PCMs have two Motorola 68HC11 computers, one for Time-based actions (like spark and fuel), and one for Event-based actions (like transmission shifting or AC request). Each has a EEPROM memory chip (Electrically eraseable Programmable Read-Only Memory) which contains executable code, enable/disable flags, constants, and lookup tables. "Tuning" or "Reprogramming" involves reading the memory to a binary file, modifying it (using a Binary "BIN" file editor like TunerCat or TunerPro), and then erasing and rewriting (or "flashing") the memory with the updated data.

The problem comes just after erasing. The 68HC11s are setup to go to a specific memory address on startup that will instruct it how to operate, including communicate with the outside world. If that portion of the code is not rewritten before a fault, the computer will not know how to communicate, thus rendering the whole PCM useless.

Historically, TunerCat, EfiLive and other reflashing tools simply wrote the whole memory chip from start to finish. If you had a fault AFTER the critical communications code was written, you could reflash it again no problem. But before, you were hosed. FlashHack (for the '94-95s) took a novel approach of writing the communication code FIRST, and THEN writing everything else, so there's only seven seconds of "vulnerability" rather than 10s of seconds. It also remembers what the last successful chunk of data was that was written, so it simply retries from that point once communications are established.

FlashHack does one other novel thing - if you read the existing calibration first, it compares the new calibration, looks for differences, and only writes the side that changed (whether T or E). This can cut flashing time from four minutes to two minutes.

So what about LT-FLASH?
LT-FLASH, although being developed by a completely different team, is going to follow in FlashHack's footsteps. The '96 computer had a lot more memory, so it takes 4 minutes to read and 15 minutes to write (or "flash"). It also has a high-speed data line (4x as fast as the stock 8192 baud line it's currently using); at some point the developers may figure this one out too, but it is not as reliable.

If you've read this far, I've got really good news; we successfully in-car flashed an Impala for the first time last weekend (9/14/24), and this weekend we just successfully in-car flashed a '96 Roadmaster wagon. We are now working on VATS compatibility, VIN consistency, and software updates.

It has been a while since I flashed my 96 with the Jet DST but I don't recall in taking more than a couple of minutes to do. I have changed programs when doing test drives even, sitting on the shoulder of the road so I would think I would have noticed it taking 15 minutes, or the police would have.

sherlock9c1 wrote:

This is really big news because the only other available option is JET DST 14005 which hasn't been updated since like 2006 and is steaming pile of hot garbage.

Funny. I don't consider the DST to be that bad, not having been updated.
Probably because it requires a COM port connection so the laptop I'm forced to use for tuning hasn't been updated since around 2006 either!!

FlashGumby wrote:

sherlock9c1 wrote:

This is really big news because the only other available option is JET DST 14005 which hasn't been updated since like 2006 and is steaming pile of hot garbage.

Funny. I don't consider the DST to be that bad, not having been updated.
Probably because it requires a COM port connection so the laptop I'm forced to use for tuning hasn't been updated since around 2006 either!!

The biggest issue when I got my DST some years ago was the COM port connection thing, and the fact that there we USB adapters, but most didn't work well. I had held off for a while because of that then they came out with an updated model that does connect via USB. I got one and it works fine, and pretty fast as I mentioned earlier. You have to run the laptop in, IIRC, in XP compatibility mode.

Update, version two of the tuning hardware has been released; the definition file (XDF) is in process; the lead developer is looking for as many BIN files as possible, so the best way to help is purchase a HW tuning kit and email your calibration file to him.

This will require a modern laptop (I use a 2 year old Dell business laptop running Windows 11). As this is still a prototype, a "write" does run the risk of needing to repair the PCM (requires disassembling the case and soldering 10-pin test headers to two boards.  The UnBrick hardware kit is inexpensive and so far has a 100% success rate.

I've PM'd all of you on this thread who expressed interest. If anyone else is interested, reply to this thread or PM me.

Here is an overview of the tuning parameters available in the '96-97 LT1 PCM:

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Sherlock9c1,

I am also extremely interested in this software. Could you please add me to your list of members you are sending additional information to?

Additionally, the youtube video is private.

I appreciate you bringing this software forward, and I am looking forward to possibly using it!

Hi brothapig, I responded to your email.

To clarify, LT-FLASH is really the hardware (SAE J1850) interface, combined with the unique hardware and software instructions necessary to read and write to the '96-97 LT1 PCMs.  The calibration editing will be done in TunerPro, and there will be unique definition files (XDFs) available shortly.

As a bonus, the lead developer has built a stand-alone addition inside LT-FLASH that will allow you to modify your rear axle ratio and shift points so that you can correct your speedometer and transmission behavior after a gear ratio change. That way you wouldn't have to use the separate TunerPro editor, which is daunting to the newbie. That is in beta testing currently.

Looks like the video settings were changed; I'll look into it.

Is this the type of tool the guy is building currently for speed, etc?  This is from my DST with a generic truck program.  When you change thing here, it does change the shift points automatically, although not always the way you might want.


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Yes, it's like that.

JET DST is heritage TunerCat, which does go change all MPH-related parameters when you make a gear ratio change. TunerPro does not, as I found out the hard way one time when recalibrating my wagon's speedometer. And then I discovered on the next drive cycle that the engine will run stable at 900rpm with the torque converter locked. (don't do this, very bad for the powertrain for multiple reasons)