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Old Nov 10, 2013 | 11:02 PM
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P0171-p0174

2004 fx4 190k miles. 5.4
The dreaded 171-174 codes. Truck has air raid intake ,Gibson exhaust ..PCM was played with years ago.last week ford reprogrammed to stock"..maf ,o2 s ,brake booster , all changed..cat s replaced 2 years ago..cel on all the time.
Fuel trims ,LT maxed at 30 ,ST18-20 ..runs perfect won't pass inspection. DMV will not register. NY ..smoke tested no vacuum leaks..I clear codes and kam within 30 minutes same thing. Help winter is coming ..
 
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Old Nov 10, 2013 | 11:30 PM
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glc
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From: Joplin MO
If you still have the stock intake, put it back on.
 
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Old Nov 12, 2013 | 07:33 PM
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Thanks good thought didn't work.
 
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Old Nov 12, 2013 | 10:54 PM
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glc
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From: Joplin MO
You have major air entering the intake somewhere after the MAF or you aren't getting enough fuel. I'd take a good look at the FPDM and change the fuel filter.
 
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