I have a 02 screw 4x4 w/ the 5.4. I keep getting the SES light w/ codes po171 and po174 and the po174 on the code scanner says "pending". I have replaced the 02 sensors{ upstream} the MAF the PCV valve AND the hose that connects it to the throttle body, and the fuel filter. I have checked and checked again for vaccum leaks and there is NONE! This is driving me absoultly crazy. The truck idles and drives fine no problems. I disconnected the battery and went through the procedure for the truck to relearn its idle and fuel trim. The light went away for a while but this morning when I took the wife over to her Mothers house it came back on again The only things that I can think of that could be causing the SES light is the harness that connects the MAF to the wiring along the inner fender where it plugs in at by the air filter housing or that I have a defective PCV valve again.

 

check intake gaskets, dpfe, clean throttle body ports. also i had the same prob. ended up being low voltage to the maf.

 

I have cleaned the throttle body, checked the intake gaskets. When I checked the codes again today I did a KOER and a KOEO. Code came up as a po1000. and the EVP light was flashing on the code scanner. The guy at orielys said try checking the gas cap. He showed me a new one and what to look for. My cap on the seal looked like it has shrunk. I bought the new cap and the truck does seem to be running a bet better. On decelleration it would somtimes hesitate.

 

i believe i just got the same code after cleaning my throttle body, seems like MPG has dropped too. how did you fix this?

 

When you cleaned your throttle body, did you install new gaskets? Make sure everything is hooked back up properly, gaskets seated like they should.

 

First know what the codes mean.
They are the "results" of the fuel tables being shifted too their lean limits trying to account for a 'rich' fuel condition after combustion.
This can be a tail chasing event started by a rich condition or it can be stated by too much air.
Seems contradictory but the hardware chain gets into the act such that the OX sensors are the last to see the end results.
The code 1000 is not a direct trouble code and is the results of you rebooting the PCM or doing a code clear.
After doing so, the PCM must test all systems as good before the code 1000 clears. A normal action anytime the PCM is rebooted 'or' a code is force cleared.
For the 171/174 codes both banks; look at the fuel regulator for leaking past it's diaphram and into the intake as raw gas.
Check possibility of leaking injectors, low fuel pressure and all intake areas for an unaccounted for air leak.
Vapor recovery system for excess fuel getting back into the intake.
EGR system allowing air to enter at any point.
The dipstick tube rust through at some point. The crankcase is a closed system and is indirectly monitored by the PCM.
A good scanner to look at all the operating PID may also be helpful if you know how to interpet the readings.
Do not depend on any scanner to tell you 'what' is faulty or what to do but to supply info on what you should look at.
It is possible for either a rich or a lean condition to cause a shift in tables and depends on the inital fault and what happens afer that for what he OX sensor detect.
Good luck.

 

^^^Ok I sorta understand what you are saying. The possibity of a leaking fuel pressure regulator makes sense. I do seem to be using a lot of fuel lately. I had the ox sensors changed a few weeks ago. Do the sensors have to be "broken in" somehow for the PCM to recailbrate to the new sensors? How hard would it be to replace the fuel regulator and/or the injectors if they are bad?

I do hear a "ticking" sound like it is comming from the clamshell housing of the air filter. if air would leak out of this housing it would cause the codes correct? Do these air box housings have a tendency to leak? if so Would it just be better to get a cold air intake?{yes I know about the gotts mod}

 

Ox sensors are ready to use as manufactured.
Air does not leak 'out' because there is a sleight vacuum being pulled by the motor.
The regulator is on the driver side fuel rail.
All injectors are 'o' ring sealed to the fuel rails and the heads.
Check for raw fuel in the vacuum hose from the regulator to the intake.
Use pressure gage to determine if there is a leak-down after the engine is shut down.
Should hold pressue for more than 5 minutes.

 

A ticking sound? What could that be? Are you sure it's coming from the air box? All I can think of is a bad MAF harness wire, at the connector inside the box.

Also, make sure your IAT grommet is tight, -not split and leaking.

Disconnect the MAF and fire it up. Is the ticking still present?