MAF gone bad?

[TrickStang37]

ok, im having a hard time finding someone to respond to my threads. when checking the MAF, jrichker posted that there needs to be atleast 10k ohm between pin C & D and ground. On my MAF i get 3.74 k ohms on D and ground and on C and ground i get .4 ohm. I went to the junk yard, and EVERY MAF was with in that range!! I doubt EVERY MAF was bad (checked 3.8's, 4.6's, 5.0's etc). I must have tested like 20 different ones. So whats the correct information??! anyone knowledgeable on this at all or know another way to test the MAF? Searches bring up nothing, usually ending with jrichker saying to check the ohms and no more further posts. I NEED HELP, PLEEEAAASE!! also, is there anyother MAF (interchangeable) that will work from other cars?

and no, my car is not bringing up any codes.

 

[NYC LSC]

Sounds like you're testing it wrong.

Have a look at what I found on Pro-M's site:

4. What is the Mass Air Voltage at idle?

Our recommendation is 0.6-.9 volts D.C. between pins C and D on the mass air while connected. Pin A = Red 12 volts, Pin B = ground negative, Pin C = internal ground 3.5-4.0 volts, Pin D = output +.

http://www.pro-flow.com/tech info/8895 troubleshooting.htm

Good luck and hope this helps.

 

[autoXr1]

I've been through your same situation. What I have found out is that when a vehicle is modified, the voltages sent to the computer from the MAF meter may not be the same as when it was stock. In addition, if you are trying to track down things like electical noise, erratic voltages, high-resistance voltage drop, etc. you need the proper data-logging equipment to track it down. Testing with a simple multi-meter will not give you any useful data unless there is something significantly wrong. It has to be recorded and analyzed through a wide RPM range.

Take the car to a reputable engine tuner with, preferrably, a Mustang/eddy-current dyno...not a Dynojet/inertial-type dyno. This is important from the aspect of tracking down voltage irregularities under different load conditions. Although, a talented, knowledgable tuner may be able to track these things down with a Dynojet. It may be that the MAF meter is just fine and you have a computer calibration issue due to your modifications...and may just need a chip.

 

[KDK1988GT]

what is your car doing??

 

[TrickStang37]

i didnt need a chip four weeks ago. i didnt need a chip running the same exact set up on the same short block/cpu for the last 3 years.

and i was just testing it based on the highly regarded jrichkers postings. I dont get the Pin A = Red 12 volts, Pin B = ground negative, Pin C = internal ground 3.5-4.0 volts, Pin D = output +." part. what does it mean? i know pin A is the 12v source and Pin B is grounds, but is it telling me to check pin C and Pin D and with what? i already knew about checking MAF voltage at idle, i get .67 or so. The car is slowly getting less drivable it feels like. it was backfiring alot today on the passanger side from what i can hear, even in nuetral and bringing the rpms up to 3000.

 

[TrickStang37]

my car is hesistating big time. checked codes, nothing. checked ACT and ECT sensors, they come out fine. checked EGR, new one now, fine. checked TFI, new one, fine. the o2's have less than 200 miles on them. checked all grounds, fine. im running out of crap to change!!

 

[TrickStang37]

http://forums.stangnet.com/showthread.php?t=517346

thats my original thread.

 

[jrichker]

What changes have been made in the air intake? Are you running a cold air induction kit? Have you tried replacing the MAF sensor? If you are running a cone type air filter, is it located in the fender well? The fan wash can play havoc with airflow through the MAF when the cone is mounted in the engine compartment. Is the 76 MM MAF a Pro-M or C&L? C&L MAF's seem to have more problems in highly modded cars like yours.

A bad MAF would set code 66. If you're not getting a 66 when you dump the codes, your problem may be elsewhere.

Here's the MAF basics so that you can review and think about the problem...

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.

Look for sudden changes in the MAF voltages across pins 9 & 50 while crusing at a fixed speed on a flat road. They are indications of wiring problems or a bad MAF sensor. Measure between pins 9 & 50, do not connect the voltmeter lead to ground.

 

[TrickStang37]

im runnin the march ram air, have been for 4 years, so its a conical filter enclosed in a box basically. I just got the car back together and the car ran PERFECT for like 2 weeks, then i got a slight miss. well, that miss has grown into almost a constant miss and i cant really find it. i got code 42 today, again, so whats that really mean? Its runnin rich on the passanger side, but what can i do? the spark plugs arent fouling or anything. im thinkin im missing spark on that side, but how can i find out? the wires arent arcing at all, tested them with an ohm reader, read perfect, the highest reading was like 2.74 ohms on the longest wires. I think it was k ohms but that was the number. changed the spark plugs couple of times, still no change. I took my coil to autozone (what a joke!) to test it because they said they'll be able to tell me if its good. I thought they had some special machine of some sort to actually test it. I had to teach the damn manager how to test it with an ohm reader!! goddamn. i already had tested it myself, but by reading the ohms does it tell me if its holding voltage correctly? AAAHHHH!!!!!!! Ive asked around on local message boards but nobody steps up to help me, I live in one of the FU.CKEN BIGGEST CITIES IN THE U.S. how is there nobody decent enough to want to help??! is there a way to test the distributor??

 

[TrickStang37]

and i doubt its the MAF, the car does this at WOT too. and I drove with the MAF unplugged around the block today, ran WAY worse. I was just lookin for a way to really test it. so what can it be? im almost ready to take offers on the car.

 

[autoXr1]

and i doubt its the MAF, the car does this at WOT too. and I drove with the MAF unplugged around the block today, ran WAY worse. I was just lookin for a way to really test it. so what can it be? im almost ready to take offers on the car.

Stop pulling your hair out and get that thing to a shop. Look, there is common diagnostic equipment that installs between the computer and the harness that will data-log all the voltages throughout the RPM range. It will find any irregularities in the voltages and end all of this guesswork. Some of the Ford dealerships have this equipment. Just make a few calls. I've done that before. Just pay them for the diagnostic fee. If the car is modified, they may not want to work on it, anyhow, but they can hook it up to their diagnostic equipment. You can replace the parts yourself if you don't want to pay them labor.