MS + OBD-II equipped car (TRACK USE ONLY)

Background: My buddy and I installed a MS-I, v3.0 on our XR4Ti track car so I am familiar w/MS, building one, hooking it up to all the sensors, and tuning it, on a non-OBD vehicle. The XR4Ti is street legal (Passes GA-smog tailpipe sniff test).

New Project: I would like to install a MS on my 1998 Cadillac Eldorado and be able to retain all of the normal ECU functions like automatic trans shift, gaugues, etc for track use (I know it was never meant to go road racing but hey it's not my DD, just my toy and I'd like to have a backup HPDE for when/if the XR4Ti is down or being driven by one of my teammates, also I'd like to use it as a test mule) which means I need to prevent the OBD-II from killing my engine/trans when I decouple some of the sensor returns. I'm pretty sure this can be accomplished by datalogging on the various signals and using various resistors on the return signals to keep everything in the green. Again, I do not care if it throws emissions check codes as this vehicle will not be used on-road as long as it doesn't do something stupid like throw the car into limp home mode or cut power, however if I am controlling fuel, timing, and spark there is very little possibility it will be able to go into limp home mode but rather I would expect it to cut power or something.

Currently: I have my FSMs and am in the process of isolating each signal and the cross communications on the returns in the OBD-II so that I can figure out which ones I 'have' to have.

Questions: If anyone has any experience, links, or contact info on individuals running MS in parallel w/OBD-II (particularly GM but any info will be helpful) again, mostly because I want to keep the stock trans and gauges, I would very much appreciate it.

I believe the last time I was perusing the MS forums, people were working on the transmission control pieces using MS. Seems like they were working on GM units.

Another thought is that the aftermarket does have transmission controllers (not sure if they have any for your particular transmission) so that might be another direction of research.

For other's reference the Eldorado could have had either the 4T80 or 4T60 transmissions

http://en.wikipedia.org/wiki/GM_4T80_transmission

http://en.wikipedia.org/wiki/Turbo-Hydramatic_125#Turbo-Hydramatic_440-T4

http://en.wikipedia.org/wiki/Cadillac_Eldorado#1992-2002

http://www.powertraincontrolsolutions.com/downloadview-details-13-4T80E_wire_harness_diagram.html

TCI Auto has a controller for the 4L60 and 4L80 transmissions. I don't know how similar it is to the transverse versions.

Generally on any car I do everything in my power to completely delete the stock ECU. There are many times that it's hard, if not impossible to share things like the crank signal between two controllers. Unfortunately a lot of it has more to do with the factory controllers input circuit vs the MS's. There is a good bit of information somewhere on the MS site about sharing resistive temp sensors. Generally it's not hard to add additional CLT/IAT sensors to most cars, and adding a wideband controller that has both a wide and narrowband O2 output (like the Innovate LC1) can keep both controllers happy.

As you know you will have to add resistors on some of the outputs to keep from throwing the open/short circuit codes.

Do you know what kind of trigger type and signal the stock computer is using for its engine speed input? Usually that's the biggest pain on the whole thing.