Guys,

I'm fairly new to computer generation cars. I'm not savvy on the whole ECM/PCM/CCM thing. However, I'm not computer illiterate either.

I've ordered a USB interface cable for my laptop to ALDL connector from AKM and plan to download the TTS Datamaster software (unless there is a collective suggestion to use another). With this, will I be able to reprogram the ECM on my '94 LT1, 6spd for my hotcam, header and maybe heads mods when and if I do them? If so, is there a tutorial or some type of instructions in the software that will tell how to do it? If not, where do I go?

Thanks,

Carl

 

You can't re-program your chip with Datamaster.

I use TunerPro to tweak the bin-file for my EPROM. After burning a new chip (using Advantech Compact programmer) I take the Vette for a spin and use Datamaster to log. I think you will find Datamaster useful but another program for changing parameters is required.

 

You are looking at two different kinds of software for two separate functions:

1. Scanning & Logging

Programs like DataMaster link to the car's PCM and record engine information in
real time on the laptop. This occurs through a connector cable like AKM's. The data
recorded includes things like RPM, injector pulse width, manifold pressure, vehicle speed,
spark advance, etc etc.

This is a read-only function. Its use is to measure & record how the car is running under
different driving conditions. DataMaster is an excellent program, and the TTS site has
good instructions on how to read and understand the information recorded.


2. Program Editing

Programs like LT1 Edit or TunerCat are used to CHANGE the PCM operating program.

This is typically done to accomodate engine modifications like new intakes, cams, heads,
headers, etc. Changes are made to the fuel and spark tables (among others) to tailor the
PCM program to the new engine parts/operating characteristics.

This is a read/write function, and there are no fail-safes - what you change in the program
has real and immediate consequences in the engine's operation. Programming for a '94 is
done by flashing the memory chips (2) directly on the PCM mainboard. This requires a
bi-directional cable between your Windows PC and the car PCM.

The cables I am familiar with are serial cables, hooked to my home PC. You need to check
with AKM to find out if the USB cable you bought supports full memory-flashing. Why is that
important? 'Cause if there is any hiccup in computer commo during a memory flash, you will
waste the PCM. Check the AKM site for info on building a bench rig to flash the PCM outside
the car - and the potential problems with flashing in the car.



As far as instructions on how to edit car programming, there is no book on what to do. The
process presumes an understanding of how engines (and computer controls) work. Your best
sources of info are probably going to be the bulletin-boards at LT1 Edit or HPTuners (the '94
PCM has more in common with the OBD2 computers than it does with the earlier models).

An example of the HPT board is here:
http://www.hptuners.com/forum/YaBB.p...num=1101917527
I put some general ramblings on tuning here:
http://www.corvetteforum.net/c4/doctorj/cartest.htm


Good luck.
DrJ

 

DrJ,

Thank you. This is very informative. Will the TTS Database perform the scan function of recording codes for diagnostic purposes?

For the one time re-programming of the PCM for engine mods, would it be more cost effective to simply send it out for the reprogramming? I assume it requires separate software?

Any recommendations on who to send it to if I choose that option?

Carl

 

If you are refering to fault codes in the ECM/PCM, yes! But Datamaster will not retrieve code from other systems. If you want to find out the other system's codes use the CCM. This is done by grounding pin G (G to A) and turn the ignition on. Then the CCM will enter diagnostic mode. It displays fault codes (in speedometer) for the CCM (module1), ECM (module4) and the EBCM (module9). End of list is indicated by "---".

 

You're welcome, Carl.

DataMaster will display (and I believe erase) the PCM diagnostic codes. I haven't used it on a '94
myself, so check the Helms manual on displaying codes from the traction control, anti-lock brake,
BCM and any other electronic processors in that car.


I believe the TunerCat Editor and $EE definiton file for your model are about $90. Even if you
choose to have someone else work on the program it's a good investment, for at least three
reasons:

a. You can check what your stock calibration looks like, and compare that to whatever a 'tuner'
gives you. That way you know what you're buying, and can learn which table changes do what
in your car.

b. If you learn to flash the PCM memory yourself you only need a file to load (from a tuner) which
you can get via e-mail. No need to physically mail the whole PCM around the country - and if
anything goes wrong with a 'tune' you can easily re-load the original program, getting yourself
out of trouble instantly.

c. No tune is perfect the first time. They can always be tweaked and improved for your individual
needs. I've been tuning on mine for several years now through a few engine combinations, and I
find working on the program is like honing a Gerber blade - the more time you spend working it,
the better it will do its job. Anticipating that you will go through a few iterations before you finish,
flashing the PCM yourself will save a lot of down-time on the car; and allow you to experiment with
different table settings yourself later on.

TunerCat's site is here: http://www.tunercat.com/


I have no first-hand experience with commercial tuning services, I do all my work on my own. The
most recent (and very modest) contribution I made to the world of tuning was described here:
http://www.thirdgen.org/techbb2/show...hreadid=296415

That being said, to answer your question about commercial tuners:

Both Alvin and tjwong post on this board, and generally have good reputations. If it were me I'd ask
for specific references on cars like yours that have been tuned for your application (street, road race,
drag, autoX or whatever). Then go with the one with the most relevant experience. People skilled
in computers will be able to answer your questions honestly - if their answers don't make sense (or
don't answer the question) try someone else.

If you have any other questions just post them here, somebody will try to help.

DrJ

 

You're welcome, Carl.

DataMaster will display (and I believe erase) the PCM diagnostic codes. I haven't used it on a '94
myself, so check the Helms manual on displaying codes from the traction control, anti-lock brake,
BCM and any other electronic processors in that car.


I believe the TunerCat Editor and $EE definiton file for your model are about $90. Even if you
choose to have someone else work on the program it's a good investment, for at least three
reasons:

a. You can check what your stock calibration looks like, and compare that to whatever a 'tuner'
gives you. That way you know what you're buying, and can learn which table changes do what
in your car.

b. If you learn to flash the PCM memory yourself you only need a file to load (from a tuner) which
you can get via e-mail. No need to physically mail the whole PCM around the country - and if
anything goes wrong with a 'tune' you can easily re-load the original program, getting yourself
out of trouble instantly.

c. No tune is perfect the first time. They can always be tweaked and improved for your individual
needs. I've been tuning on mine for several years now through a few engine combinations, and I
find working on the program is like honing a Gerber blade - the more time you spend working it,
the better it will do its job. Anticipating that you will go through a few iterations before you finish,
flashing the PCM yourself will save a lot of down-time on the car; and allow you to experiment with
different table settings yourself later on.

TunerCat's site is here: http://www.tunercat.com/


I have no first-hand experience with commercial tuning services, I do all my work on my own. The
most recent (and very modest) contribution I made to the world of tuning was described here:
http://www.thirdgen.org/techbb2/show...hreadid=296415

That being said, to answer your question about commercial tuners:

Both Alvin and tjwong post on this board, and generally have good reputations. If it were me I'd ask
for specific references on cars like yours that have been tuned for your application (street, road race,
drag, autoX or whatever). Then go with the one with the most relevant experience. People skilled
in computers will be able to answer your questions honestly - if their answers don't make sense (or
don't answer the question) try someone else.

If you have any other questions just post them here, somebody will try to help.

DrJ

 

Drj,

You make it sound like something I'd like to try. It will be a few months before I do any mods, but I'll be sure to learn all I can by "playing around" before I start changing anything. I like your Gerber sharpening analogy.

Carl

 

Nice post.

Just wanted to add.. You can order the original USB datalogging cable capable of flashing 94-95 cars from moates.net. Its very relieable and very professional looking.

If you have any questions while tuning feel free post here. Just because me and TJwong are in this buisness doesn't mean we don't like to help people.

And as long as the question is not like "I just got my datalogging cable/software, what do I change now?" you should be entertained by plenty of answers.

 

Here is another source of information on my friend LJ's website:

http://para.noid.org/~lj/

Just click on the link "PCM Tutorial" This applies mainly to the 94/94 F and Y body PCMs so this will directly help you. The basics are the same since the inception of GM computerized control from even the old C3 days. One thing to remember is to make small changes one at a time. And always make notes as to what these changes are, and save the original file as well.

Funny for me, I help more people tuning vettes here on the forum than I actually tune in my shop. I actually tune more trucks and SUVs in my shop than I do F and Y cars. The most popular are 383 based TBI pick ups, and 383 based vortec small blocks in the earlier 96 and up trucks. Not to mention the 2000 and up LS1 based trucks and SUVs.

 

Carl, I saw the pedigree in your 'member's bio' and thought you might recognize the name
Me, I 'm old enough to remember(barely) all the parts in a Garand. Let me know if you need
any help with the computers, they've become a hobby of mine lately.

Dave

 

All I've managed to do at this point is load the drivers for the cable from AKM. My work will be a long drawn out process. I'll pop up infrequently as I progress. I live in Flag and commute to Albuquerque weekly. I travel all the time and tend to focus my weekend time with my family. Hence, the vette and bike get secondary attention. I know you don't need the personal snibble, but it does explain why I pop up in spurts with ????? First I need to replace the left half axle stud, or whatever, that's leaking from the rear end.

I guess I can get one of the softwares at least and drive around, get used to and learn before I start rearranging ones and zeroes.

Again, thanks for everyones responses and offers to help. I'll take a step back and read my Helms manuals that I've had for a few months. I take it this car has an ECM, PCM, and CCM? I understand one should reprogram the PCM on the bench and not in the car, correct?

Carl

 

Re programming the car Powertrain Control Module (PCM), read sections 2 & 3 here for detail:
http://www.akmcables.com/techinfo.htm

Me, I'd flash the thing out of the car, using either a car battery or a dedicated power supply
(running off the house mains) for 12+v power. That's just based on my experience with
chip flashing -serial commo is a fragile process- others may see it differently.

You will need to look in the Helms book to get the pin locations on the PCM box - AKM
calls out four (4) power pins and four (4) ground pins but you'll want to check that.

You'll also need to verify with AKM that the cable you have is suitable for chip flashing,
in addition to its 'data logging' function.


Re the acronyms, just look in the Helms to see what is in there controlling what. Programmable
processors are commonly used for security, climate, brakes, traction, and suspension control -
as well as the PCM for eng/trans. Details vary by year.

 

Drj,

Andrew at AKM says it will handle memory flashing.

Carl

 

What Helms manual are you referring to?
Is it something I can read to make me feel less overwhelmed by the technology gap from my early '80's shadetree experience to my '90 corvette wake-up call?
Ed

 

It's the shop / service manual. For my '94 it's two volumes and cost ~$100.00. I forgot where I ordered it, but it was on a link I got from this site. Perhaps someone will jump in and post a link for you.

I've used it a couple times, but I have to admit that I haven't read it thoroughly to learn about the computer stuff.