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My Name is Lee Davidian
And i need to ask is your 3.0 liter engine a Flex fuel? Vin # is the eighth digit is it a 2 or S??
Too, Code P0174 is hardly ever attributable to faulty 02 sensors. For one thing, the odds of both upstream sensors going out at the same time are pretty slim. Secondly, that code, while related to the fuel management system, do not tell you that there is anything wrong with the 02 sensor units or circuits; they only indicate that the sensors are encountering and/or reporting a lean condition in both banks for which the PCM can no longer compensate (i.e., long-term fuel trim limits have been exceeded).
It is wise, therefore, to approach the problem from the perspective of a lean condition first, before condemning the 02 sensors or their circuits. Lean condition = too much air or not enough fuel, or a combination of both. Hence, you want to look out for the usual lean suspects, some of which have already been noted: upper or lower intake gasket leaks, leaks at the vacuum and air hoses/connections that run to and from the upper intake, PVC system leak, EGR system leak (or system malfunction), dirty MAF sensor, and also fuel-delivery issues such as clogged filter/injectors, weak fuel pump, faulty regulator, etc. A fuel pressure check would be a nice thing to do if possible.
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PO174 FUEL TRIM SYSTEM LEAN BANK 2 CONDITIONS. OTHER POSSIBLES CAUSE FAULTY FUEL PRESSURE REGULATOR.AIR LEAKS IN THE INTAKE MANIFOLD, EXHAUST PIPES OR EXHAUST MANIFOLD.LOOK FOR A VACUUM HOSE DISCONNECTED, BROKEN, LOOSEN,FUEL CONTROL SENSOR OUT OF CALIBRATION LIKE ECT IAT OR MAF.USE CODE SCANNER ERASE CODE.IF CODE PO174 STILL REMAIN CHECK THOSE THINGS I MENTION ABOVE INFORMATION.
TRY CLEANING FUEL INJECTORS.DIRTY CLOGGED FUEL INJECTORS WILL RESTRICT FUEL FLOW GIVE YOU A LEAN FUEL MIXTURE.TRY A BOTTLE OF SEAFOAM POUR IN A FULL TANK OF GAS SEE IF IT HELP.
I really doubt the fuel injectors are the problem here. do a vacuum hose leak test, poss EGR problem as well
HOOK VACUUM GAUGE TO INTAKE MANIFOLD YOU NEED AT LEAST 17 - 20 HGS VACUUM.IF VACUUM LOW AROUND 12 - 14 HGS YOU HAVE INTAKE MANIFOLD LEAK OR POWER BRAKE LEAKING WILL CAUSE VACUUM LEAK.
WELL EGR VALVE FAULT WOULD CAUSE ROUGH IDLING AND STALLING.COULD BE BROKEN VACUUM LINE TO FUEL PRESSURE REGULATOR. OR FUEL PRESSURE REGULATOR FUEL SOAKED CAUSED BY RUPTURE DIAPHRAGM.
CHECK FUEL PRESSURE SHOULD BE 26 - 45 PSI. NOW IF FUEL PUMP SOME TIMES THEY WILL GET OLD AND WEAK.CAUSE LOW FUEL PRESSURE THAT WILL CAUSE FUEL LEAN CODE TO SHOW UP.
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This code is usually caused by leaking intake manifold gasket on the front side. With the engine running, spray carb cleaner or ether on the gaskets. If the engine revs at all, you have a leaky gasket. If not, check for other vacuum leaks in anything attached to that side of the manifold. If you have more questions, please let me know.
This is likely the problem, the O2 sensoras were just reading the lean condition, so yes a trained ford tech would have NOT replace the rather expensive O2 sensors, that is throwing parts at the problem, one lean code may indicate a bad sensor.
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I did fix a vaccum leak and the problem is still there.
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