Volumetric efficiency (VE), is typically defined as "the actual amount of air being pumped by the engine as compared to its theoretical maximum." VE can vary a great deal between engines, but typical "good" numbers would be between 70% and 90% for naturally aspirated engines.
Technicians have used VE in order to help identify mass air flow sensors that are not measuring the incoming air mass correctly. It can also be used to identify mechanical problems.
To calculate an engine's VE, the following PIDs must be used:
Setup your scan tool to record these PIDs and then take the vehicle out for a test drive. There are differing opinons as to what point in the test drive that the data is collected. A little wisdom goes a long way here... Engines do not breathe the same at all rpm ranges and with the introduction of variable valve timing and electronic throttle control, using VE as a "diagnostic" can be tricky.
One school of thought is to capture your scan data and find the inputs for the VE calculator at wide open throttle and max rpm. Another school of thought is to find the inputs at wide open throttle and low rpm. Whichever method you use, be sure to use the same method at all times. This way your data will have value to you.