[juddev]

This is not my car and I dont know anything else about it.



1990 Buick Reatta Coupe with 4.9L V8 Cadillac Eldorado motor, This engine conversion is basically a bolt in, not butchered, major improvement over original V6. Car is very clean, very nice interior, V8 has about 30000 miles, asking $4500 obo, must sell, 651-270-1318

* Location: Lake Elmo
* it's NOT ok to contact this poster with services or other commercial interests

Click Here

[Jim]

The car was at the Back to the Fifties car show last weekend at the MN fairground and it was in the swap meet on Sunday. I looked at the car and it is still pretty nice. The car was at my home here in Duluth about 10 years ago and the installation looked like the factory did it. It is showing a little wear under the hood but the car still looked quite good.

[KDirk]

Ok,

I have to ask (if Jim or anyone else here knows):

How did they adapt the PCM? I gather the 4.9 PCM was transplanted (need to control 8 injectors, not 6), but is it piggybacked to the 3800 PCM, or was the 4.9 Cadillac PCM "patched" to work seamlessly with the rest of the electronics?

I can't tell for sure from the pics in the ad, but it looks like the stock instrumentation is still in the car.

This is a mod that I would almost like to do, as I love the 4.9 PFI engine (it's in my Deville) but I hate to knock the 3800 as it is remarkably reliable.

Anyway, I hope someone knows the details on how this was done, or can point me in the right direction.

KDirk

[nic walker]

Heck, the link has been deleted [img]<>/frown.gif[/img] ??????

[D-a-n-i-e-l]

Here is how it would work without too much of an issue. The subframe, BCM, are the same as a Eldorado. This means the ECM out of the same would comunicate with the BCM in the Reatta and any of us that have added the compass or radio brains know that the display control will addapt on its own. So all in all it would be a quick easy swap, with the hardest part being a possible repin on the ECM plugs.

I would do it for some one for little to nothing. I may even think about buying one building it up a bit and slapping it in to mine or an other low end 88'-89'Reatta

[padgett]

Except the serial data steam from the Cad ECM is different from the Reatta. Heck the 90 Reatta data stream is different from an 89. The BCM uses this stream to drive the gauges. Get it rong and the displays read strange things.

[D-a-n-i-e-l]

Padgett,

Do we know that the 89' caddy stream is diffrent from the 89' Reatta? I know I am currently using a 89' caddy BCM in my Reatta (proms switched of course).

If the streams are diffrent then that would mean that the code for them is stored in the proms?

[KDirk]

I'm pretty sure the data formats are different Cadillac vs. Reatta for identical years, even if we are talking only about E platform. Heck, the Toronado (the Reatta's second closest cousin after the Riviera in terms of on board electronics) is a lot different, and except for the compass module, RKE, CPS, RIM and outboard cassette, most of the modules (or at least the ROM's within) are different from the Buick E-platform cars.

The data format is determined by the PROMS (or CALPAK if you prefer GM speak) which is one reason why PROMS have to be swapped into a replacement ECM or BCM, even if the module itself is used in several different cars.

Enough is now known by tuners about the GM OBDI system that the ECM data streams are pretty well documented. BCM code, and what it expects to "see" on the data line is not well documented at all, and there seems to be little interest in doing so now, as the cars that use this format are a minimum of 14 years old now (1996 and up are OBDII/Class 2 or later on CAN network, not OBDI/UART 8192 format). Obsolescence has killed the possibility of reverse engineering this part of the system it seems.

That is why I am curious how they did it. Mechanically, it is clearly no problem to do this swap; it bolts in complete, cradle and all. I have to think they edited the PROM code however, to make it play nice with the Reatta BCM or the gauges and diagnostics would not work right, if at all. If this was done, I wish someone could produce the doc's on what was changed to gain compatibility.

Knowing the differences that exist, a drop in PCM swap just doesn't seem possible without complications.

KDirk

[padgett]

Not neessarily the format (it is all in bytes) but the order changes. The most complete listing I have found is in a file called ALDLSTUFF from ftp://ftp.diy-efi.org/pub/gmecm/

[imported_55chevy]

Originally Posted By: nic walker

Heck, the link has been deleted [img]<>/frown.gif[/img] ??????

Must have sold