I know it sounds like a stupid question, but I am in the process of working out a deal with a guy for a complete RamJet 350 system, computer, harness, everything.....and intend on installing it all in my 1993 Z/71. The Z/71 has the PCM which controls transmission functions along with the normal engine stuff. I'm trying to see if it is feasible, or even possible, to use the MEFI4 to run the engine and somehow piggyback or integrate the truck's factory PCM to allow it to control the transmission. Any thoughts?

Yes, it is possible and it has been done to piggyback two ECM/PCMs. Using the added one to run the engine with the stock PCM staying to run the trans. Some sensors are shared between the two. Such as the TPS, DRP, & VSS. Then the system grounds, battery and IGN+.

The trans signals stay with the PCM while the remaining engine controls (IAC, EST, CTS, etc) go with the ECM.

Have you considered a '7730 running the $8D code in place of the MEFI? IIRC the MEFI controllers can only be programmed by a handful of companies.

RBob.

Hey there, RBob.....no, I never considered a '7730, cause I am not familiar with them. I was leaning toward the MEFI4 cause it comes with the system and I have the correct cam already to put together a poor man's RamJet 350. I've looked at www.mefiburn.com and while the software is expensive, well, so is all the stuff needed to tune what I already have. The stuff to tune the '7427 with a flash chip, the ZIF adapter, and AutoProm would run over $360 plus shipping, and then I would have to tune the thing in.....
My thinking is that by using the MEFI4, I get a factory tune, and can fine tune it in later.....like if I upgraded to FastBurn heads or an LT4 cam or LT4 HOT cam and kit.
Thanks for your response, I will consider it.
Now.....anyone able to point out the steps needed, materials, etc, to make a piggyback harness?