Volumetric Efficiency (VE) Test Procedure
While graphing the PIDs, accelerate at wide-open-throttle (WOT) to near redline in first or second gear. Capture the movie or screen on the Scan Tool and return to the shop to enter the peak RPM and MAF values into the VE calculator along with intake air temperature, altitude, and engine displacement. The VE calculator will let you know the engine’s breathing efficiency.
Interpreting Test Results
The table below shows approximate ranges for the test. As you can see, sometimes the results aren’t clear because some engines are naturally more or less efficient. For example, a 2-valve pushrod V8 from GM doesn’t breathe very efficiently even when new, and 80% is a decent result. On the other hand, a 4-valve Hyundai with variable valve timing and intake tuning should get to 95%. Therefore an 80% result on a 5.3L Yukon V8 is a pass, but on a 2.4L Sonata it’s a fail.
The good news is that the results are often very obvious, so don’t worry about the ‘fuzzy’ result range unless you have to. Even then, you can often reason your way through a result. For example, if our hypothetical Sonata barely runs, our ‘failed’ 80% result does indicate a fault, but isn’t bad enough to explain the barely running engine. Look for something else. On the other hand, if the complaint is ‘it seems like it doesn’t have as much power’, the 80% result completely explains that symptom.