Nissan Technical Advisor 2/1/2011Yes you're correct. Black smoke is caused by too much fuel being processed inside your car's engine and then released from the tailpipe of your car. Malfunctions in fuel delivery or internal system leaks will cause black smoke to come from the tailpipe. Airflow in an injection engine is controlled by the throttle body; fuel is distributed directly in each cylinder. This creates better fuel control, lower emissions and faster acceleration. The process of measuring the amount of fuel a fuel injector is dispersing is determined by the PCM (powertrain control module). The fuel injection system has several parts: the mass airflow sensor or map sensor, throttle body, throttle position sensor, idle control valve, fuel pump, fuel pressure regulator, fuel lines, and oxygen sensors. Get the engine scanned to determine the faults and post it here.