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99 explorer running rough and vibrating

Lee's Automotive

Git-R-Done
Elite Explorer
Joined
September 23, 2020
Messages
1,558
Reaction score
2,147
Location
United States
City, State
Alabama
Year, Model & Trim Level
99 Explorer XLT 4.0 SOHC
Hello I have a 99 explorer 4.0 SOHC and it runs really rough when cold and at operating temperature i have changed the intake gaskets upper and lower egr tube o ring iac gasket egr gasket and the fuel filter along with the dpfe sensor i have also cleaned the iac and MAF the idle will go to 500RPM and then drop and almost stall and go to 1000RPM sometimes it will stall really need some help on this one not sure if its a vacuum leak or what's going on at this point i'm also getting codes p0171 p0174 using forscan
 



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Check pressure at fuel rail.... sounds like it's acting up enough to perform test during one of these incidents.... fuel pump could be on it's way out....they'll hang on for a couple weeks or more before completely giving up the ghost...
 






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Does this look right all of the were taking at idle except number 4
 






Bump
 






Things to check...

  1. Replacing the fuel pump.
  2. Replacing the fuel filter.
  3. Replacing the fuel pressure regulator.
  4. Replacing the powertrain control module.
  5. Replacing one or more injectors.
  6. Replacing one or more oxygen sensors.
  7. Replacing the mass air flow sensor.
  8. Repairing a vacuum leak.
 






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