F-150 Running Rough-Help!!
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Joined: Jan 2003
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F-150 Running Rough-Help!!
Can anyone help? I've got a 97 F-150 with the 4.6 liter engine that had been running fine, I parked it and didn't use it for a week. When I went to use it the next time, the truck was running really rough, especially under partial throttle. I replaced the fuel filter and reset the computer by disconnecting the battery. The truck ran fine for a weekend and I parked it for another week. When I started it a week later, the same problem occurred. I drove the truck to a parts store that will read the OBD II code. The code scanner showed 174 and the guy said I needed the downstream 02 sensor, so I forked over the fifty bucks. I installed the sensor and the truck runs a little bit better, but is still pretty rough. I looked in my Haynes manual and it said code 174 was for some kind of lean fuel problem. There was a separate code for the 02 sensor.
Anyone have any ideas? Any help would be appreciated. Thanks.
Anyone have any ideas? Any help would be appreciated. Thanks.
Last edited by Zigracer; Apr 24, 2004 at 08:30 PM.
Lead Driver
Joined: Dec 2003
Posts: 6,773
Likes: 7
From: On the road in Ohio
Try checking for vacum leaks, the pcv tube that runs from the passenger side valve cover to the back of the engine, there is a rubber boot that likes to crack and cause a lean condition, see if this helps.if it is the rubber boot post back i got a neat fix for it.
Elder User
Joined: Sep 2002
Posts: 772
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From: White Sands, NM
From the service manual:
H41 DTCs P0172, P0174, P0171 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM
Diagnostic Trouble Codes (DTCs) P0171 bank 1 (Cylinder 1) and DTC P0174 bank 2 indicate the fuel/air ratio is too lean. The fuel trim system is at the rich correction limit.
DTC P0172 bank 1 and DTC P0175 bank 2 indicate the fuel/air ratio is too rich. The fuel trim system is at the lean correction limit.
Possible causes:
Fuel system
Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Contaminated fuel injector(s).
Vapor management valve (VMV) leaking.
Induction system
Air leaks after the MAF.
Vacuum leaks (vacuum lines and gaskets).
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated engine oil dipstick.
EGR System
leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.
Base engine
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2S(s).
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks
H41 DTCs P0172, P0174, P0171 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM
Diagnostic Trouble Codes (DTCs) P0171 bank 1 (Cylinder 1) and DTC P0174 bank 2 indicate the fuel/air ratio is too lean. The fuel trim system is at the rich correction limit.
DTC P0172 bank 1 and DTC P0175 bank 2 indicate the fuel/air ratio is too rich. The fuel trim system is at the lean correction limit.
Possible causes:
Fuel system
Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Contaminated fuel injector(s).
Vapor management valve (VMV) leaking.
Induction system
Air leaks after the MAF.
Vacuum leaks (vacuum lines and gaskets).
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated engine oil dipstick.
EGR System
leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.
Base engine
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2S(s).
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks
