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Mass air meter may be shot

  • Thread starter Thread starter Mr. Getbad
  • Start date Start date Aug 26, 2004
M

Mr. Getbad

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Aug 24, 2004
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Aug 26, 2004
#1
  • Aug 26, 2004
  • #1
I'm getting a code 66,and I have a question for you guys. My car runs better with the meter unpluged, No popping or missing. So would it make any difference if I was getting 12v to the meter or not? I'm trying to figure out if its the meter or the wiring.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
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Aug 26, 2004
#2
  • Aug 26, 2004
  • #2
first thing i would do is clean the maf up. elec contact cleaner seem to work for folks (Im SD).
good luck.
 

jrichker

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Aug 26, 2004
#3
  • Aug 26, 2004
  • #3
Some more info in your Sig would be helpful to troubleshoot your problem. Car year & mods are very useful when we look at possible problem causes.

Do you have a Cold Air Intake?, If so, rotate the MAF to a different position. That will change the airflow, and MAF performace.

If you have a stock airbox, read on...

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 (usually pins A & B).

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).

There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element casing 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 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
 
M

Mr. Getbad

New Member
Aug 24, 2004
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Aug 26, 2004
#4
  • Aug 26, 2004
  • #4
I have a 90 lx
306
Procharger 14#'s
Pro-M Univer
42# injectors
AFPR set at 45#
Stock heads
Ecam
Holly Systemax intake
75mm Tb
Timing at 23 (spout out)
A9p computer, No chip

It all started with an intake swap. Can a vaccume leak throw that code, and cause popping and missing? I can take the car out and it wont be that bad. The further down the road I go the worse it gets. I pulled of to the side of the road and unplugged the mass air meter it cleared up some. So I don't know if its the meter or a vacumme leak. What does it sound like to you guys.
 
M

Mr. Getbad

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Aug 24, 2004
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Aug 26, 2004
#5
  • Aug 26, 2004
  • #5
Meter cleaned, helped a lil bit. Problem still there.
 
M

Mr. Getbad

New Member
Aug 24, 2004
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0
Aug 26, 2004
#6
  • Aug 26, 2004
  • #6
Ok I checked the meter and this is what it read.
A&B wires 11.86 V
C&D wires between 0.51 & 0.59V at idle.
So what do you guys think now?
 

jrichker

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#7
  • Aug 26, 2004
  • #7
Is the MAF a blow thru or is it in front of the supercharger intake?
 
U

ucanbeatme

New Member
Aug 19, 2004
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Williamstown, NJ
Aug 26, 2004
#8
  • Aug 26, 2004
  • #8
did you car come stock with Mass air or was it added?
 
M

Mr. Getbad

New Member
Aug 24, 2004
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Aug 27, 2004
#9
  • Aug 27, 2004
  • #9
Its a blow thru meter, My car came with mass air from the factory.
 
M

Mr. Getbad

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Aug 24, 2004
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#10
  • Aug 27, 2004
  • #10
TTT
 
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