(looks like I just wrote a novel :))

Well, I know I'm not exactly on the correct site for this, but there are no performance forums for my car and I came here once before and you all were a big help!

Anyways on with my question: I have a 1995 Cadillac Fleetwood and was told it has almost the same engine as the Corvette. It's an LT1 350. I want to adjust a few things with the computer now (like change the tire size to fix the speedometer) and I'm wondering about the programs out there that can do this.

So far I've found three options:

1. Hypertech said their Power Programmer III will do it, but I would have to special order it directly for them since the normail ones aren't set up for any Cadillac VIN's. Also the programmer only allows me to change the tire size from 24-27" and, although close, my tires are barely outside that range. Cost would be roughly $350. http://www.hypertech-inc.com/

2. There's a guy that sales programmed PCM's and would send me a PCM programmed how I want for my car. Although he say's he can do it, I'm just concerned that their might be a problem considering my car is a Cadillac and this is usually done for Corvettes, Camaro's, Impala SS's. I don't know if their is any difference in the engine specs and if the PCM controls other features in the car like the air ride and traction control. The cost to go this route would be $214 and I would get to keep my original PCM as a spare. http://www.pcmforless.com

3. I could buy a copy of LT1_Edit and try and figure out how to do everything myself. This would be the most powerful way to go, but since I'm a complete beginner at this it would also be the most risky way to go. I'm sure I could mess something up pretty easy! Cost for the program and a OBD1 cable would be about $250. http://www.carputing.com

Any feedback you can all give me will be very helpful and if anyone has used any of the above tools for programming their PCM (especially the DIY method) I would love to hear your experiences!

Also, does anyone think I can mess up my Cadillac considering all of these were generally created for sports cars?

Thanks,
Gary

 

Gary-


Sounds like an interesting project, and like you are doing your homework. Here are a couple of thoughts:


GM generally uses the same computers across several car lines - so although Cad isn't mentioned (who hotrods Cads?) your engine computer probably uses an $EE type program, per the info on this site:
http://www.geocities.com/ecmguy.geo/tuning/do_tune.html

[Note: Your car PROBABLY has at least 3 computers installed - one for the engine/drivetrain (the one everybody modifies), one for the dash display & ride control, and one for the ABS system - there may be more, I dunno. The last Cad I owned was like a '56.]


I note from this site that at least one person has copied a 94 Fleetwood engine file that you can look at under the LT-1 editor, so there must be copies of the engine program around somewhere:
http://www.bfranker.badz28.com/LT1Edit/LT1files.htm


Last, there is another option for editing engine programs - Tuner Cat. I use a version of this for my '91 project. I haven't used the later year stuff myself, but on my project it works great. It's also like only $100 to buy. TC is good on tech support, and has his own bulletin board where some pretty good tech's post from time to time - follow the links on the site to find it. You might send him an e-mail and tell him what you are trying to do, maybe he knows if it works.
http://www.tunercat.com/


If it were me I'd find a copy of a Fleetwood engine program somewhere (they are posted as computer files at various spots around the Net so you'll have to look), get a copy of an editing program (like TC or LT-1 Edit), and open up the program on your desktop computer - you can do this without going anywhere near the car! If it looks like something you can learn, then you are all set to start - if it's beyond your skill set, you can always turn it over to a pro. Not everyone enjoys computers as a hobby.

If you decide to try modifying the computer program yourself you will also need some kind of data recording device to see what your changes are doing to the actual car - there are a couple of free ones around that might work, and several commercial programs at various prices. Look on the PROM FAQ page at the 3rd Gen Board.

Hope this helps
drj

 

Thanks for the quick reply! It was very helpful. Those sites you linked to helped alot.

I'm thinking I might actually order the PCM from pcmforless.com and then still keep my options open for getting a programmer (thanks for the tip on tunercat) to tune things up later down the road when I start adding more mods to the engine. It will cost me alot more that way but, if I can convince myself to part with the money, I'll have a backup computer just in case I mess up. I know the going rate at the dealer is $400 for one.

 

I agree with doctor jay. Download tuner cat (free trial). Get a program that will work with your PCM and play around with it. You should be able to do all the editing you need to with tuner cat.