- A vehicle with a MAF sensor
- A VE calculator
- A Scan Tool displaying the following PIDs
- MAF in grams/second or pounds/minute
- RPM
- IAT (air temperature affects density)
- Barometric value (or check online for current atmospheric pressure)
VE | Interpretation |
---|---|
90% or More | No breathing faults are present, or at least they are so minor that they will not cause a code to set or a customer to report a symptom. Note that non-turbo engines with very clever engine and intake designs may exceed 100%. |
76-89% | The ‘fuzzy’ zone. Consider the engine design (e.g. number of valves, number of cams, use of VVT, use of variable intake). Also consider whether the vehicle is designed for performance, economy, or workload when calibrating your expectations for this test. The higher the result in this range, the less obvious the symptom, so consider the severity of the fault you are diagnosing before jumping to conclusions. |
56-75% | This range clearly indicates a breathing problem. Use Fuel Trim to determine if this is a real breathing fault or just a sensed breathing fault. |
55% and less | Very few engines will even run if the actual breathing is under 55%. However, if it’s a ‘fake’ breathing fault, then Short Term & Long Term Fuel Trim may be able to add enough fuel (often over 50% combined) to keep the engine running. Therefore, if your results are in this range and the engine runs, verify high Fuel Trim and then diagnose |