A MAF is a MAF, Right? Well…

The Mass Air Flow sensor measures the mass of air entering an engine.  The fuel injection uses this and other information to predict the correct fuel/air mixture.  The MAF sensor used on the Cadillac STS-V and several other GM vehicles is the ACDelco 213-4222, GM p/n 15865791.

Looking up the intake tube at the MAF

Looking up the intake tube at the MAF

This sensor is actually made by Hitachi.  It is a combined sensor, and measures the mass air flow as well as the temperature of the air passing through the sensor.

The Camaro Community has discovered that not all examples of the same part number have identical responsive properties.  Summary.

This MAF is a card type MAF, which allows use of the same low-restrictive flow MAF sensor in a variety of intake diameter systems.  The Camaro and the STS-V for example use the same sensor.

What the hu-bub is about is that some lots of the sensor are –while working correctly — less responsive, and some lots are more responsive.  Although the part numbers are the same, the more responsive examples have a letter-number lot code along the side of the device, as opposed to a single-letter designator for the less responsive examples.

My STS-V MAF sensor is a “D” model, so I have ordered a cherry-picked letter-number model from Apex Motorsports to replace the current one.  I hope to swap to the more responsive MAF next trip to the dyno.


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