Yes, anything that is physically attached to the engine and conducts electricity should be a ground. There should be a large chassis to tranny ground under the airbox and a smaller ground wire from chassis to an area around the alternator. Ground cables and throttle cables are also mentioned in many of these threads:
i havent seen a ground near the alternator....I keep searching for the ECU pin out of a 91 na and a 95 jdm turbo...where can i find this? I have reason to belive wiring might be my problem. I bought the car with a 95 jdm 3s-gte. Theres these 2 wires just hanging around the fusebox, its a black with yellow line and a yellowish with a redl ine. I cant figure out what these are.