There is no computer in the sense of a single, easily identifiable box like a desktop PC in a 1993 Pontiac Grand Prix 3.4L V6. The engine control unit (ECU), sometimes called the Powertrain Control Module (PCM), is the electronic "brain" managing engine functions. It's a fairly small, black box, usually located somewhere under the hood, often near the firewall or tucked away in a less conspicuous area. Its exact location can vary slightly depending on specific trim levels and options.
To find it, you'll need to consult a repair manual for your specific 1993 Grand Prix 3.4L V6. A Haynes or Chilton manual will show you a diagram and describe the location. You could also try searching online for "1993 Pontiac Grand Prix 3.4L V6 ECU location" along with images. Remember that accessing the ECU may require removing some plastic covers and/or other components under the hood.
