Abstract: An evaporative fuel leak diagnosing apparatus for an internal combustion engine, which can detect a pressure of concern with high accuracy with a structure implemented inexpensively while ensuring high accuracy for the detection of fuel vapor. The apparatus includes a computer unit (50A) for fetching directly non-linear outputs of a pressure sensor (6A), determining a pressure detection value within a furl tank (1) on the basis of the non-linear output value of the pressure sensor (6A) and data registered previously on the basis of the non-linear output value of the pressure sensor (6A) as fetched from the computer unit for use in evaluating the actual pressure corresponding to a noted pressure sensor value.

Abstract: A mass airflow sensor is provided with a system of conduits and ports which connect the mass airflow sensor to a main fluid flow channel. Pairs of ports connect the plurality of fluid interconnection conduits with the main fluid flow conduit being monitored. The mass airflow sensing apparatus is adapted to receive a mass airflow sensor in fluid communication with its system of conduits. First and second pairs of ports are disposed upstream from a third and fourth pair of ports. The first and second pairs of ports are connected to each other in a way which provides an average flow from each of the pairs to an inlet of the mass airflow sensor. In a particularly preferred embodiment of the present invention, the outlet of the mass airflow sensor is connected to an arrangement of conduits and ports that is a mirror image of the upstream arrangement of conduits and ports.