CEL codes & some other questions

[LCM99]

I have a 1997 Expedition 5.4L 183,000 miles. It's been idling rough for a long time, but has gotten really bad recently (drops to 500 rpm while idle, have to keep the throttle down while stopped). The check engine light came on too, got it checked and these were the codes - P0171, P0401, P1131, P1151. So the engine's running lean, but why? I've seen that elbow in the back of the engine can go bad, but it doesn't feel like it's drawing air (but there's a sucking sound somewhere in the engine). Should I replace that whole vacuum line anyway? I cleaned the MAF, replaced the air filter and cleaned the throttle body a little bit last weekend. Anyone have any suggestions of what I can do next?

Also, I've always had this weird thing where the "vent" & "floor/vent" have always kicked on the A/C when it's to "cool", even with the knob not turned to A/C, which is fine, didn't really bother me. Today though, the front vents totally stopped working, and everything blows out the defroster vents up front (hot, cold, A/C, normal vent, etc.). The rear blowers work just fine. What happened?

Also as long as I have this thread going, my truck squeeks really loudly when I steer or go over even the slightest bumps. It's really noticeable when I'm going slow, can't tell when I going faster but that's probably just because I can't hear it. What do you think is wrong, and is it "bad" for the truck (can I keep going like that)?

Thanks for any help you guys can give!

 

[2blackfordrides]

May have a answer for blower problem.... My expy did the same and come to find out the knobs for heater controls had small cracks in them which made it so it didnt turn the selector to position i turned it too..... Not sure its the right answer... Just figured i would share....

 

[LCM99]

I'll check the knobs tomorrow and see if they look alright, thanks for the info.

 

[KWT2000]

alright many problems here... the squeaking suspension is most likly ball joints and tie rod ends very common as they cannot be greased from the factory.... for the a/c it sounds like broken blend door or blend door actuator... as you only have code for bank 1 running lean check for exhaust leak on that side... i think po401 is egr low flow which is probly the DPFE replace the unit and use neopreme lines on it. i will look up the other codes and post again

 

[KWT2000]

ok po1151 is bank 2 sensor 1 not switching... po1131 is bank both sensors reading out of range...po171 is bank 1 running lean...po401 is egr insuffient flow caused by bad egr valve or DPFE... If this were my truck i would replace all 4 o2 sensors and the pcv valve and line since youll need to sooner or later...also replace the DPFE and clean the IAC motor and replace the fuel filter and put some seafoam in a couple tanks good luck

 

[LCM99]

I took my vehicle to a friend of a friend about a year ago for a bunch of work and I thought he replaced the tie rods and ball joints, guess he didn't do that great of a job. Do you think they just need to be greased or replaced all together. Will it harm it just to squeak?

I'll take a look into the blend actuator & door and find out more about that.

Where would I check for an exhaust leak on that side? I'm assuming it's on the engine block and not into the exhaust system (tailpipe, muffler, etc), correct?

Autozone's computer said the P0401 was an "EGR system fault: The RCM has detected too little flow on the ERG system. Probable cause: -Blocked passage on EGR system, -Failed EGR valve, -EGR solenoid faulty, -Failed EGR pressure sensor where applicable, -Failed EGR position sensor where applicable."

The P0171 said "Fuel trim bank one condition. The powertrain control module uses the oxygen sensor to calculate the Air/Fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only. Probable cause: -If one bank and two codes set together suspect fuel pressure or MAF sensor, -Oxygen sensor defect, -Igntion misfire-repair, -Fuel injector problem."

I recently cleaned the MAF following this guideline here, looked perfect, made sure it was installed correctly and not broken when finished, though could it still be bad?

Also how much do you think a DPFE & lines would set me back?

Thanks for the help.

Edit: I'll start looking into replacing the o2 sensors, the DPFE, the fuel filter, and the pcv valve/line. Is the IAC fairly easy to remove and replace, its so far back to tell. Not really looking forward to putting all this $ into it but I guess it's still cheaper than taking it somewhere. :/

 

[LCM99]

Quick question about the O2 sensors, you say there's four of them. Can you buy the same sensor for all four of them or are they all specific?

 

[KWT2000]

the DPFE on the aftermarket will be $50-70 with the neopreme lines... dont use rubber vacum lines as they break down from the heat and plug up the DPFE... check for exhaust leaks at the manifold and between sensor 1 & 2 first gen expys are known for breaking exhaust studs and leaking... as for the ball joints i cant imagine some replacing them with non serviceable units if there greaseable get them greased asap if there not check them i bet there wore out if they are im very partial to moog suspension components... the IAC motor is on the passenger side of the intake held on with 2 bolts... goodluck

 

[KWT2000]

Quick question about the O2 sensors, you say there's four of them. Can you buy the same sensor for all four of them or are they all specific?

bosch has one part# for the front and a diff part# for the rear. i say bosch because almost all o2 sensors are bosch with different names