Electrical New Codes 29/98/66 - wont run unless MAF unplugged (all volt and ohms checked at maf)

Good evening,

I have been reading over the site for the past few days. Ill explain my issue , what ive done and any suggestions from you guys are appreciated.

I have a 91 5.0 that I purchased earlier this year. Mods are: Cobra intake, BBK 70MM TB, BBK shorty headers, off road exhaust . Smog delete, Egr delete.

When I got it the previous owner had the MAF unplugged because he couldnt get it running right. He also told me that he had the ECU replaced because he couldnt figure out the idle problem. When I brought it home, I fixed all vacuum leaks coming from Brake booster and old Egr hoses still hooked up. Now the only vacuum I have hooked up is for vent air control, brake booster, and FPR. All extras are gone. Everything has been fine ever since I fixed all these issues even though me CEL is on. That is until recently.

It started with the car dying when I hit the gas, so I brought it home and now it wont even start unless the MAF is unplugged. Using a code reader I get the same codes ive gotten since day one which are: KOEO 31-81-82-85-84.... but now the new codes I get are 29-66-98.

So VSS and Maf issues.... on with the fun!

I looked around to see what I could do here are my results for volt/ohm checks at the MAF plug/sensor:

Between power and ground getting almost 12 volts
Between MAF Signal and MAF Return getting 15k OHMS
Between MAF and Neg Battery terminal key on is like .7volts and when start car it goes up to 1.2 volts and then the car dies.


Now I am trying to figure out what to look at next. I am thinking about replacing the MAF sensor or Unit completely. Im not sure what housing it is, but its a Ford sensor. Im pretty sure its not even the original because its a E9ZF-xxxxxx-xx and I think it should be a F1 code. Even my BAP sensor is a E7EF-12A644-A1A. I know some things are pieced together on this. What are some techincal suggestions you guys may have for me next since these voltages and ohms seems to check out. Thank you!
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Can you post a picture of the MAF? Also, are the injectors the stock 19 lb/hr units? If you do not know what color is the top of the injector? Just trying to see if you have a “calibrated” MAF for larger injectors.


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That appears to be the stock MAF sensor for a 55mm MAF - AFH55-03 is what gives that away. Orange tops are 19 lb/hr so you seem to have the correct injectors.

Do you have another EEC that you can try? If not you probably need to crack the case open on the one in the car and see if you have any issues with the caps or any burnt traces. Seems the common theme here lately has been the processor has an issue and needs to be either repaired by the owner or by shipping it off. Here is a thread on how to replace the caps:

Place most are sending them to get repaired is here:

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I'd try cleaning the ma F sensor wire with ma F cleaner. Then if it doesn't help switch out the sensor.
Vss code could be posted wire ,check those . Good luck.