: GM MAF sensor information and Discussion



AJxtcman
12-27-07, 07:43 AM
The thread recently about cleaning a MAF got me thinking. One post referred to an LS1 web site. Problem is an LS1 MAF is a Cold wire not a hot wire. It maybe digital also. Currently I work with a minimum of 7 different types of MAF sensors. That is just at a caddy dealer. I have several laying around and I will post all the information I have on all of them.:D

AJxtcman
12-27-07, 07:52 AM
This is from an 07 Escalade:D
This is s front shot. Note NO screen
http://i224.photobucket.com/albums/dd25/AJxtcman/MAF/07MAFfront.jpg

This is from the back side.
http://i224.photobucket.com/albums/dd25/AJxtcman/MAF/07MAFback.jpg


This is the inside.
http://i224.photobucket.com/albums/dd25/AJxtcman/MAF/07MAFinside.jpg

Circuit/System Description
The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF/IAT sensor has the following circuits:

• An ignition 1 voltage circuit

• A ground circuit

• A MAF sensor signal circuit

• An IAT sensor signal circuit

• A low reference circuit

The ECM applies 5 volts to the MAF sensor on the MAF sensor signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 1,700 Hertz at idle to near 9,500 Hertz at maximum engine load.

Onalaska
12-27-07, 08:01 AM
What are those little pipes sticking up off the main bar? Is this the digital type without the hot wire?

AJxtcman
12-27-07, 01:59 PM
What are those little pipes sticking up off the main bar? Is this the digital type without the hot wire?







http://i224.photobucket.com/albums/dd25/AJxtcman/MAF/07MAFinside.jpg


The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor.


That would be " Resistors" between the "pipes". This is used for IAT

Submariner409
12-27-07, 03:38 PM
The little heated resistors are part of the frequency generation circuits - they're the shiny bars spot welded between the vertical "pipes". The IAT is the black thermistor on the airfoil mount. There are 5 connector pins: 3 for MAF, 1 for IAT and 1 for ground reference. There's a pretty good electrical diagram in the '02 FSM.

(Take a look at the ambient temperature sensor mounted on the front of the radiator/hood latch brace. That is also a thermistor: a resistor which changes value over a calibrated temperature change. Same principle as the cabin air temp sensor, that fan-fed unit behind the 1" square dash grille just left of the steering column which gives some owners a squealing sound in the winter.)

AJxtcman
12-27-07, 08:13 PM
The little heated resistors are part of the frequency generation circuits - they're the shiny bars spot welded between the vertical "pipes". The IAT is the black thermistor on the airfoil mount. There are 5 connector pins: 3 for MAF, 1 for IAT and 1 for ground reference. There's a pretty good electrical diagram in the '02 FSM.

(Take a look at the ambient temperature sensor mounted on the front of the radiator/hood latch brace. That is also a thermistor: a resistor which changes value over a calibrated temperature change. Same principle as the cabin air temp sensor, that fan-fed unit behind the 1" square dash grille just left of the steering column which gives some owners a squealing sound in the winter.)

I am at home and was just thinking about my post today. it is a Thermistor not a Resistor for the IAT sensor. Thank sub

DomDeville
04-04-09, 01:59 AM
I take it that the pictures posted are of an inline MAF. Mine is a little clip that plugs into the stock air box.

Submariner409
04-04-09, 08:49 AM
That's your IAT - Intake Air Temperature sensor. The actual airflow sensor in your car is attached directly to the throttlebody, ahead of the butterfly.

Go to www.rockauto.com and get to Cadillac, Deville, 1999, emission, mass airflow sensor. Click on the blue (!) icon for a bigger picture of the part. Then go to fuel/air and do the same for intake air temp. Then go to 2002 Seville and look at the difference in the MAF - the IAT in this case is a tiny black thermistor in the side of the MAF bore.

Dom, Take a look at your similar post next to this one.