I recently purchased a 1988 speed density mustang that the prior owner converted to mass air using the X3Z Computer. I have a A9L that I want to swap in place of the X3Z and my question is do I have to do anything special with the wiring or pins, or is it just plug and play?
read this before you do the swap, if you're using a cobra MAF, then you'll have some fuel metering issues...however, yes you can just pull the old one out, and pop in the new one-after you disconnect the battery of course
Personally I would stick with the A9L. The X3Z computer is actually a little less aggressive with the fuel and timing, according to most.
It is unclear (to me anyway) if the MAS from a 5.0HO (A9L) can be interchanged with the MAS of a 93 Cobra (X3Z). If you do switch computers I would recommend changing everything to the new combo.
What MAF are you running?
I am using the x3z, but the tweecer will allow me to play with the fuel and timing, and possible import the A9L tables directly.