MAF Sensor Help Please

['88Cobra]

I just bought a used MAF sensor for my car and I'm suspecting that it might not be working or that some part of the wiring is not working. When the car is running, it still runs like it did before the MAF conversion. I need to know if there is any way to test the MAF sensor to make sure it is working, and is there any way to test the wiring? Thanks in advance for any help and/or comments.

 

[Scorcher2005]

are the sensor wires clean? What brand of meter? Is it the right calibration?

Edit: I see its a C&L...I've heard some people w/ complaints about those. You should look into a Pro-M meter.

 

[Mean86GT]

it has to be working if thecar is running....

 

[dstanggt50]

You can chk to see how much voltage the maf is reading @ idle. Thats what I did when my maf was bad, but I knew someone that had one of those star testers that the techs use. I think the snap on scanner can read it also, but most just chk w/a volt meter, but I don't know which wires hook up the voltmeter or anything.

 

[jrichker]

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.


If the computer detects a MAF problem, you'll probably get a code 66.

Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.

There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.

The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).

The MAF output varies with RPM which causes the airflow to increase or decease. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.

There should be a minimum of 10K ohms between either pin C or D on the MAF and ground.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

To clean the MAF, remove the MAF element and gently spray it with electrical contact cleaner. You can also use non-flammable brake parts cleaner (same chemical in a bigger can & cheaper too). Let it dry and put it back in.

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp

 

[CManT1914]

it has to be working if thecar is running....

The MAF can not be working, and the car will still run. Trust me, I'm on my 4th one. jrichker nailed everything there is to do in testing a MAF sensor. An easier way though, is to unplug it while the car is running. If the car runs the same with it unplugged, then it's most likely bad. If the MAF is working properly, then the car should start running like crap, and possibly stall when the MAF is unplugged.

 

[Mean86GT]

The MAF can not be working, and the car will still run. Trust me, I'm on my 4th one. jrichker nailed everything there is to do in testing a MAF sensor. An easier way though, is to unplug it while the car is running. If the car runs the same with it unplugged, then it's most likely bad. If the MAF is working properly, then the car should start running like crap, and possibly stall when the MAF is unplugged.

ya thats why the 3 that i have seen wouldnt run when the intake pipe fell off

 

[CManT1914]

ya thats why the 3 that i have seen wouldnt run when the intake pipe fell off

Well obviously if the damn pipe falls off it's not gonna suck any air through the MAF, and it's not gonna register any incoming air, the computer won't send any fuel. But see then it wouldn't be on the car would it? And actually, when my Pro-M fell off (all three times) the car still ran, it just kept wanting to die.

BUT... the MAF can be on the car, NOT working, and the car will still run. I KNOW this, because two of my MAF's have broken, and the car still ran. It ran crappily, but it still ran.