I've got a 96 Impala I have put a 94 LT1 into. I have the 94 PCM and knock sensors. The transmission is a T56.

Its my understanding that all I need to do to convert to OBD1 is plug and play. Change the tac signal to a 4 cylinder signal and maybe wire the knock sensors in parallel??

https://buickforums.com/forums/threa...to-obd1.13374/

The conversion is not hard at all. You obviously need an ODBI computer with a 95 B body tune, because of the PWM TCC in the 95-96 transmission. With a non Impala SS, you only have to worry about the knock sensors. The Impala SS you have to convert the tach signal to a 4 cylinder signal.

The pre-96 B body used 2 knock sensors wired in parallel. The 96 uses 2 knock sensors attached to two adjacent pins on the PCM. The resistance of the knock sensors are different also. The rear O2s and crankshaft position sensor (CKP) are on unused PCM pins, so you don’t have to worry about them.
To fix the knock sensor problem you have two choices. You can change the knock sensors to the 94-95 B-body sensors or add a resistor.
With either choice you must connect the two knock sensors together so they are in parallel.
You have two more choices, modifying the wiring harness or modifying the PCM. Modifying the PCM allows you to switch PCMs back and forth for emission testing, selling the car, etc …
To mod the wiring harness, find the BLUE connector on the PCM and connect the wires at pin 21 (Light Blue) and pin 22 (Dark Blue) together. ODBI only uses pin 22 (Dark Blue). If you did not change the knock sensors, you must attach a 2K resistor to this wire and connect it to ground.
If you can solder you can mod the PCM. Open the PCM and connect pins 21 and 22 (blue connector) together and run the 2K resistor from 21 to ground.