Response time test apparatus for a mass air flow sensor

A response time test apparatus for a mass air flow sensor (10) mounted on a sensor manifold (12) connectable to the air intake manifold of an internal combustion engine. The test apparatus has a connector member (28) to which the sensor manifold (12) may be attached and a primary manifold (30) connected between a vacuum source (46,48) and the connector member (30). The primary manifold (30) has a first branch (32) and a parallel second branch (38). The first branch (32) has a first sonic nozzle (34) and a first valve (38) controlling the air flow through the first branch (32). The second branch (38) has a second sonic nozzle (40) and a second valve (42) controlling the air flow through the second branch (32). The first and second sonic nozzles (34,40) producing substantially different air flow rates in the primary manifold (30). An electrical control (50) sequentially activates the first and second valves (38,42) to produce a step change in the air flow rate through the sensor manifold (12), records the output signals of the mass air flow sensor (10) and determines the response time of the mass air flow sensor (10) in response to the step change in the air flow rate. The electrical control (50) also is capable of comparing the response time with a reference time to detect each mass air flow sensor (10) having a response time greater than a specified response time.