How Well Does the Engine Breathe?
All technicians know that an engine has to have good compression in order to run well. But an engine also has to “breathe” well, or be able to move the air in and out with minimal restriction. Restricted catalytic converters, improper cam timing, even clogged air filters, can impact the ability of the engine to do this with various driveability concerns as a result. In addition, many of today’s cars use Mass Airflow sensors to tell the ECM how much air is being drawn in. If this information is incorrect, the ECM will not supply the correct fuel charge for optimum performance and may also result in the Check Engine light illuminating. There is an easy way to tell if the engine’s ability to “breathe” or an inaccurate MAF sensor are the cause of the driveability complaint you are diagnosing. It’s called Volumetric Efficiency and is a measurement in percentage of the actual ability of the engine to move air versus what it could move in a perfect world. To use this test, you need a scan too
