Q: My car is not starting when the MAF sensor is plugged in - 1991 Nissan Serena

This may be a sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor. When this fails, this can cause an imbalanced air/fuel load to be supplied to the motor which often times results in the engine starving for air or fuel.

This is what causes the hesitation or loss of power you describe. This can also cause the engine to struggle to idle for the same reason. In your case, when unplugging the mass air flow sensor, your car’s engine is bypassing the mass air flow sensor input into the ECU causing it not to have a reference point for air/fuel mixture. This may momentarily start the car, but it will not run correctly or rev up normally as you have experienced.

I would suggest having a professional, such as one from YourMechanic, come to your home to diagnose and replace the mass air flow sensor.