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About bwnunnally

Bruce Nunnally is an independent Blogger who writes Cadillac Conversations on all things Cadillac. Connect with Bruce on Google+

A MAF is a MAF, Right? Well…

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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.

 

Adjustments for the Spectre Intake

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After some discussion I have made the following adjustments to the intake install:

After install at the dyno with change notes added

Re-route hoses under the corner of lines:

New MAF clocking closer to 11:00 when viewed from passenger side:

Next headed out to do new temperature comparison runs.

 

Update:

I reclocked the bottom of the intake (changed the relative orientation of the pieces) to ensure clearance away from the fan shroud.

It would be handy if the parts had indicators that showed the correct relationship.  I also had a great deal of trouble getting and keeping the circular gasket gasket in the hole.

HP Tuners Dashboard monitoring IAT1 during cruise

My initial results looks promising in that IAT1 during cruise now goes near ambient as expected.  After I reset the battery the Scanned Ambient went to 32F, slowing coming up to 52F by the end of test 2.  I assume it has a delaying function since generally ambient temperatures don’t change very quickly.

Cadillac Video HPTuners Dashboard playback showing IAT2 trends

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Here is a short video capture of an HPTuners VCM Scanner output of a test run to monitor intake air temperatures through the MAF (IAT1) versus after the intercooler (IAT2) or ambient.

The source video was over 1080 pixels but Youtube offers it for viewing in up to 1080p so please select the highest resolution your playback can handle and hit the fullscreen gadget for the video then pop back and comment.

I am still synthesizing the data.  It appears to me that as the STS-V accelerates the IAT2 temp rises from 131F to 151F the slowly drops down again.

There is some Knock retard coming in at high RPM.  The V will also pull timing at higher IAT2 temps.

Let me know what you think about the run data and this method of reviewing it.