2000 expedition running very lean

[dunn logan]

Hi forum pals,
I am new member here, with a problem 2000 expedition. My engine light is on. The codes are0171
P0174
P0303
The engine is running is very lean on both banks, and It is badly misfire and engine is driving rough. I did check the PCV hose, and they are very weak at their conections. Took the car to my local pepboys to get the #1 and 2 bank (O2 sensor), PCV hose and valve, and EGR valves to get change. They said the the valves and hoses did not need to get change but the engine light refused to turn off because of the misfire as they claim.
Can you please help me solve this problem and what needs to be fixed?
thanks in advance.
dunn

 

[cali]

My guess would be a coil pack going bad. I just dealt with the same issue. Turned out I had one getting ready to die and one was dead.


98 Epy 2WD XLT 115K

 

[tonydiv]

Start it up and get out a can of starting fluid and start spraying it around the all vacuum lines, especially that big elbow behind the throttle body. If the rpms jump then it's a vacuum leak.


Other things that can cause a lean condition.
Dirty / damaged mass airflow sensor
Bad O2 sensor(s)
Bad / clogged fuel inector(s)
Fuel filter

 

[tmajikman]

My supposed to be elbow on the back of my intake is actually a straight through, uhgg, most of the codes will point you to your solution, but I would go with the aboved mentioned issues, the vacuum hoses can create big problems.

 

[HFFH]

when mine was runninh ruff and throwing lean codes i had bad rubber hoses. one hose accualy colapesed on on itself. also the mass air flow sencor went bad in mine and ran ruff.

 

[dunn logan]

Well I want to autozone and change the MAF sensor, the engine light went off and it did drive smooth for a while. the next day, the engine light came back on so I I checked the #3 fire order/cylinder because it started misfiring again. It had some liquid on the wiring and it was very dirty. I suspect the liquid is antifreez. will change the #3 ignition coil on monday and recheck all vaccum holes as you guys showed me in my reply.
what could that liquid in the combustion chamber means? does it means that I have a damage cylinder head gasket/seal? or a damaged intake, exhaust gasket/seal?
help! help! and thanks again
dunn