bkrepindy

I'm almost done installing my new engine and all that is left to do is plumb the fuel system and install the DFI. I want the car to function like it is straight from the factory (ie. cruise, gauges, AC, all works). What I'm not sure of is how to marry the two sytems together. I know Fast Tracks Performance makes a unit to splice the two together, but I can't get a hold of them and they are not calling me back.

Does anyone have any suggestions????

I would appreciate it.

Injuneer

I found the easiest thing to do was keep the stock PCM along with the aftermarket computer. You will need it for PASS-Key, VSS/speedometer, fuel pump on/off, and a number of other interfaces. I run a MoTeC M48Pro in parallel with the stock PCM.

You need to keep the Opti pulses paralleled into both units. That gives you the fuel pump control and the tachometer. I also keep the IAC motor on the stock PCM (the MoTeC will only handle pulse width modulated IAC, not the GM "stepper" motor). I also added a second coolant temp sensor and a second IAT sensor, since you can't feed two computers with one sensor. The TPS and MAP are paralled into both computers. That allows the stock PCM to control idle exactly the way it normally does. That also allows the EEC, EGR and AIR to function, if you want to go that far.

With this setup, the A/C responds correctly, and the IAC responds to A/C operation. Cruise gets the info it needs, so that works.

Other than the speedo and tach, all the other dash gauges (oil pressure, charging system volts, coolant temp, fuel level) are direct feed from independant sensors, and do not require anything from the stock PCM.