I have a 79 280z i just aquired trying to get smogged running way to rich.
The ECU controls the rich and lean. The EU gets it's info from the water temp and block temp sending units (same part, 2 different spots). Replace ECU. Also, make sure your Air Control Unit is working. That gizmo has a hose going to the front and rear of it and has it's own small internal heater the size of half a small postage stamp. Within it is a hole that a shutter opens and closes. Open when cold, closed when warm. Shutter works via the little heater and thus bending metal. Sits on top drivers side of engine.
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