Mustang Keeps Going Into Closed Loop/open Loop Won't Read Maf

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mark32

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Nov 15, 2015

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May 2, 2017

#1

• May 2, 2017

• #1

Okay so the other day I was cleaning the maf sensor on my 2003 gt with the maf spray cleaner, the air cleaner was dirty so i washed that also it has the bbk CAI. After I had cleaned the maf up I let it sit maybe 5 mins and I put it back in and started the car up and it ran really rich so I hooked up my scanner and no codes but for air/fuel mix it showed closed loop running off O2 sensors. I threw the maf from this car into another to see if I had a bad maf and the other gt did not start at all. So I took the maf off the other running gt and threw it on this one and it now just goes into open loop due to insufficient air temp. I tried to reset the ecu pulled the neg cable and turned headlights on. Not sure what else to do. I'm not sure if I short circuited something. Maybe I didn't let the maf dry long enough I was rushing a bit.

 

wmburns

SN Certified Technician

Aug 14, 2009

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May 2, 2017

#2

• May 2, 2017

• #2

Just wondering. What model year did the "other" MAF come from? Could it have come from an older Mustang? One with a separate IAT sensor?

If a MAF without the internal IAT is swapped into a car that needs a built in IAT it would cause an IAT related fault.

 

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mark32

Member

Nov 15, 2015

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May 2, 2017

#3

• May 2, 2017

• #3

wmburns said:

Just wondering. What model year did the "other" MAF come from? Could it have come from an older Mustang? One with a separate IAT sensor?

If a MAF without the internal IAT is swapped into a car that needs a built in IAT it would cause an IAT related fault.[/QUOT

wmburns said:

Just wondering. What model year did the "other" MAF come from? Could it have come from an older Mustang? One with a separate IAT sensor?

If a MAF without the internal IAT is swapped into a car that needs a built in IAT it would cause an IAT related fault.

Click to expand...

its the exact same model 2003 gt that i got it from. It has the 6 pin connector

Click to expand...

 

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mark32

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May 3, 2017

#4

• May 3, 2017

• #4

The MAF I used is exact same they are both from the same year car . I'm thinking I might of short circuited something in the ecu maybe because I think the maf was still a bit wet or moist when I reinstalled it. Not sure where to look on the ecu if that's even possible . pretty much what's happening is the ecu I not getting the signal from the MAF I'm guessing or that's what I'm assuming.

 

wmburns

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May 3, 2017

#5

• May 3, 2017

• #5

Test for key on +12 volts at the MAF Red wire using a KNOWN good ground.

IF no voltage suspect a blown F2.2 fuse. In fact, it's not a bad idea to check all fuses.

DOUBLE check the wires to/from the connector. Have you ever "probed" the connector during tests? If so, there's a possibility the female connector has been spread and not making good connection.

Considering that this problem began after performing work on the MAF it just stands to reason that is where the problem is.

Does your scan tool have access to operational data? If so, monitor the MAF and IAT values.

 

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mark32

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May 3, 2017

#6

• May 3, 2017

• #6

So I looked at the reading for the air temp and maf and nothing it just stayed at zero also checked the f2.2 fuse and its a 5amp fuse but its not blown.

 

wmburns

SN Certified Technician

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May 3, 2017

#7

• May 3, 2017

• #7

mark32 said:

So I looked at the reading for the air temp and maf and nothing it just stayed at zero also checked the f2.2 fuse and its a 5amp fuse but its not blown.

Click to expand...

Have you CONFIRMED power at the MAF? Remember that it's a powered sensor that REQUIRES power to work.

But........ I believe that you have found the primary problem (no MAF signal at the PCM). So the problem is either:

• disconnected MAF or other connector problem
• wiring fault between the MAF and PCM
• no power to MAF
• Bad PCM

 

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mark32

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Nov 15, 2015

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May 3, 2017

#8

• May 3, 2017

• #8

Yeah there is power and good ground I took the PCM out right trying to see if I can find any fried connections can't see to find the pin looking for the 3 pins 36 39 and 88. Do you know which pin is which the ones sticking out ? Also i see 4 souder connection's that are balled up

 

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mark32

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May 3, 2017

#9

• May 3, 2017

• #9

Also I checked the return signal and got voltage so the maf connector is working I'm going to double check the connection between the maf connector to the pins if there isn't a connection problem then I'll look into the PCM more

 

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mark32

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May 3, 2017

#10

• May 3, 2017

• #10

Okay so I checked the connection between maf connector and PCM connector and I have come to the conclusion that it indeed is the PCM that has short circuited somewhere but now I'm not too sure where to look on the PCM to fix it.

 

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mark32

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Nov 15, 2015

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May 3, 2017

#11

• May 3, 2017

• #11

Ok so the problem has resolved itself somehow idk how maybe it was me redoing all the wiring connections unplugging everything and plugging it back in but it works now!. Lool . thanks for all your help wmburns I really appreciate it.