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EricFromCT
EricFromCT, Ford Lincoln Mercury Senior Master
Category: Mercury
Satisfied Customers: 3575
Experience:  ASE, Ford Lincoln Mercury Senior Master, Diesel, Kia Professional Elite
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04 monterey 4.2 p0190 p0191 changed the pressure sensor and

Customer Question

04 monterey 4.2 p0190 p0191 changed the pressure sensor and fuel filter
Submitted: 1 year ago.
Category: Mercury
Customer: replied 1 year ago.
Idk what it could be it backfires and if you floor the gas it will miss and if u slowly let off the gas it will straighten up some
Expert:  EricFromCT replied 1 year ago.

Hi. Sounds like you might have a Mass Air Flow Sensor issue. Can you disconnect the MAF sensor on the airbox and see if it operates differently? Then please let me know.

Customer: replied 1 year ago.
I did that and it shuts the car off i use my scanner and that same code comes up
Expert:  EricFromCT replied 1 year ago.

Ok. Those codes are for the fuel rail pressure sensor circuits. Since the sensor is new, the cause of the codes is probably a broken or chaffed or corroded wire on one of the wires from the sensor to the pcm.

Customer: replied 1 year ago.
My scanner says fp vac psi 20.0 is that the fuel pressure
Expert:  EricFromCT replied 1 year ago.

The scanners I see use FRP for fuel rail pressure. If that is, it is too low. That sounds like it is engine vacuum.

Customer: replied 1 year ago.
do u think the pcm got wet what do u recomend me doing i took the negative terminal off for 15 min and as soon as i put it back on it ran great till it warmed up then started again p0191and p0174 idk
Customer: replied 1 year ago.
I dont hear any vacum leaks when i disconnect the fuel pressure sensor there is vacum
Expert:  EricFromCT replied 1 year ago.

You have circuit codes so you need to either trace the wiring back and look for chaffing. Or you need to access the vehicles computer and then check the resistance of the wires from the pcm to the fuel pressure sensor.

Customer: replied 1 year ago.
u dont think its the fuel pump
Expert:  EricFromCT replied 1 year ago.

Low fuel pressure can cause the p0174 and p0191. The p0190 can only be set by a circuit. Could it be possible that the p0190 was set by accident from you disconnecting the connector on the sensor?

Customer: replied 1 year ago.
Im sorry it was a type error it is p0191 and p0174 thats it
Expert:  EricFromCT replied 1 year ago.

Alright. You should either check the fuel pressure manually, try a pump, or make sure you are reading the correct reading from the sensor with your scan tool.

Customer: replied 1 year ago.
Ok i will try the pump then should i change anything else?
Expert:  EricFromCT replied 1 year ago.

No. You already did a filter, which is usually done with a pump.

Expert:  EricFromCT replied 1 year ago.

When you remove the pump take notice if there is debris in the fuel tank or not.

Customer: replied 1 year ago.
Ok well tyvm appreciate all your help
Expert:  EricFromCT replied 1 year ago.

You are welcome. If you need more assistance later on please request me and we can continue.

Customer: replied 1 year ago.
Can i come back to this conversation and talk to u
Expert:  EricFromCT replied 1 year ago.

Yes. You can bookmark the page and come back. Hope I have been of assistance. Please rate my service and let me know the outcome.

Customer: replied 1 year ago.
I def will tyvm
Expert:  EricFromCT replied 1 year ago.

Sounds good.

Customer: replied 1 year ago.
Ok changed the pump and still same thing
Expert:  EricFromCT replied 1 year ago.

There must be something that is being over looked. The computer is adding a lot of fuel to bank 2 indicated by the p0174. Reasons for p0174 could be these:Fuel System.

  • Fuel pressure regulator (leaking, faulty).
  • Fuel filter plugged, dirty.
  • Fuel pump (weak, check valve leaking).
  • Leaking/contaminated fuel injectors.
  • Low fuel pressure or running out of fuel.
  • EVAP canister purge valve leaking (when the canister is clean).
  • Fuel supply line restricted.
  • Fuel rail pressure sensor (incorrect reading).
  • Ethanol content in the fuel

Air Induction System.

  • Air leaks after the MAF.
  • Vacuum leaks.
  • PCV system (leak or valve stuck open)
  • Improperly seated engine oil dipstick.
  • Air induction turbulence due to incorrect air filter.

Exhaust System.

  • Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets)

EGR system.

  • Vacuum hose disconnected on EGR System Module (ESM) applications
  • EGR valve tube/gasket leak
  • EVR solenoid vacuum leak

Secondary Air Injection.

  • Damaged/malfunctioning secondary air injection system (mechanically stuck valve).

Air Measurement System.

  • MAF sensor (contaminated, damaged, or faulty

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