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i'm stuck and pulling my hair out p0171 and p0174

FYI Autozone and Oreillys do give you the choice, when you put in 98 explorer tell them 4.0 OHV..........

there were two 4.0 V6 engines OHV and SOHC....so go ahead and reach past the 6 foot social distancing barrier and smack the back of the head on the Autozone employee

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You can show them on their own website where it gives you the choice between SOHC and OHV 4.0

The SOHC INTAKES are way different then the ohv...

98 ranger will work as in 98 the ranger only had the ohv


yep i really would like to go and smak some of them lol thanks
 



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Great way to clean fuel injectors but there's a filter inside the injector that needs to be replaced in order to maintain the correct spray pattern. This is kinda how I rebuilt mine...

 






i got it all put back together started it up everything seemed fine it was running smooth no leaks anywhere ,
its been ok but today i got the p0171 code that's the only code i get , the air filter is only a day old the mass is new
all the vacuum lines have been replaced , did another smoke test nothing , i did upper and lower gaskets on the pleum
fuel injectors cleaned and new o rings they were seated and did a leak test no fuel came out ,
i changed the DPFE ,idle air control valve ,egr vacuum solenoid valve ,
so i am just missing something its got great pickup even with the code on no heasation ,
no stalling ,great power seems better than before , so the only thing i can think of to do is chance out the bank 1 o2 sensor ..
either that or tear it back down again and start over , and replace the fuel injectors , its running a lot quieter than before ..
i m so close to having this fixed , its very frustrating i have been working on this car for 7 days now . just not sure what to do next
i really don't want to take it in but its looking like i might have to .
thanks to everyone who has helped , if any one has any other thoughts or ideas about this please let me know ..
 






Those small vacuum lines can throw a code. The hard part is finding one that has a hole in it. Even a small pinhole can cause a code...been there. Check the upper and lower intake manifolds for cracks as the plastic becomes brittle after years of use. Another problem witrh the upper manifold was warping on these engines. Other causes can been bad wiring to the sensor(s), or sensor itself.
 






Well done! Sounds like you are making good progress
so lets just look at the new code
P0171

A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled.
There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor Possible cracked vacuum or PCV line/connection Faulty or stuck open PCV valve Failed or faulty oxygen sensor (bank 1, sensor 1) Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!) Exhaust leak between engine and first oxygen sensor

Read more at: OBD-II DTC: P0171 System Too Lean (Bank 1)
Copyright OBD-Codes.com
 






So any exhaust leaks?
You said you checked fuel pressure and it passed....what does that mean?
 






Well done! Sounds like you are making good progress
so lets just look at the new code
P0171

A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled.
There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor Possible cracked vacuum or PCV line/connection Faulty or stuck open PCV valve Failed or faulty oxygen sensor (bank 1, sensor 1) Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!) Exhaust leak between engine and first oxygen sensor

Read more at: OBD-II DTC: P0171 System Too Lean (Bank 1)
Copyright OBD-Codes.com


so i changed the o2 sensor out and now its giving me p0174 plus p0171
 






So any exhaust leaks?
You said you checked fuel pressure and it passed....what does that mean?

fuel pressure test they hook up a pressure gage to the schrader valve on the fuel rail . see photo 60 psi so it was good rules out the fuel pump .no exhaust leak
smoke test ruled that out
 

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There is a rubber "Y" elbow that connects to the IAC valve, it's very common for it to have small crackes that can't be seen with the naked eye or a smoke machine. There's also a rubber hose that connects the PCV valve to an oil baffle. It too, is a common problem to start tearing and cracking on high mileage Explorers. Check out this thread.

 






this is my IAC direct bolt to the housing ..
PCV valve and hose are new
but thanks for that every answer is helpful !!
and mine is a 1998 4.0 ohv different set up than the guide you provided
but thanks again
 

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i am going to take it apart again , i am going to order new fuel injectors and wait for them to come in before i do it , should be here fri
what i don't understand is why its great for a few hours and then plop back to p0171 and p0174 its not making any sense to me whatsoever . see photos below . well wish me luck i hope this does the trick
 

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DON'T TAKE IT APART YET
wait a second people, you said the result of the fuel pressure test was 60 psi?
60 psi is tooooooo low

Your fuel psi should be 62-68 you may have a weak fuel pump
Meaning its making adequate fuel pressure UNTIL it gets hot or demand is high, so seeing 60 psi on a cold fuel pump is close to enough PSI but it is NOT ENOUGH psi......I would revisit the fuel pressure test

Running lean both banks is usually air leaks or low fuel pressure (weak pump, clogged filter, bad regulator)
 






DON'T TAKE IT APART YET
wait a second people, you said the result of the fuel pressure test was 60 psi?
60 psi is tooooooo low

Your fuel psi should be 62-68 you may have a weak fuel pump
Meaning its making adequate fuel pressure UNTIL it gets hot or demand is high, so seeing 60 psi on a cold fuel pump is close to enough PSI but it is NOT ENOUGH psi......I would revisit the fuel pressure test

Running lean both banks is usually air leaks or low fuel pressure (weak pump, clogged filter, bad regulator)


fuel pump was checked at the ford house 60 psi cold 65 hot so he said it was good , he was also saying that they recommend this see photo , i am going to change out the valve cover gaskets as well , the new set has a upper and lower gasket for the plenum as well as the plastic rings not pictured , and i have new injectors on the way so we will see
 

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copy that 65 hot is fuel pump check
 












i just bought this set will get them tomorrow along with new fuel injectors , thanks for the reply
 

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well this morning i finally got all my parts for the car i am going to install , new fuel injectors plus got the right gasket set this is the part number for the gasket set , its good at autozone and o reillys auto,
VS50209

plus just google the number and it will come up on several other sites
the part number for the fuel injectors is 0280155735 you should have no problem finding them . wish me luck i hope that this fixes the problem
i am so tired of getting the codes p0171 and p0174
 

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your 98 has EGR you should really replace the large EGR O ring...... I am not sure if it is included in that Mahle set you have...

Fel Pro 71202

Ford part F67Z-9J469-AA


I use vaseline to help seat the O ring, so it does not pinch or crush
 



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so still going threw hell with the car ,i got it all put back together on wed and it fired right up , but it was running rough so i waited til thr
to figure out what i did wrong , well i was checking my torque and discovered that the front stud was not tight at all ,so took it back apart
and got the plenum cover of started to remove the stud and the head snapped off . see photos so i could not get it out , i ended up filing
the sides to get a pair of vice grips on it and got it out , and in doing so i rounded out the stud hole , so went and got a rethreader and ill be damned 3 turns and it snapped off in the hole . the problem is that it snapped off with a point (see photo )and i can not get a bit in there to drill it out , i order some dewalt bits from amazon and just waiting for them to come . , in the meantime went down to walmart and bought a cheap set and can not make any progress with them a set of 10 i have all ready broken 5 of them and dulled out the rest of them . i was just lucky in away because monday i went to the junk yard and got an extra set of studs its the only ford they had was a 2000 so they did fit , so any one doing this job i suggest going to a junk yard and getting studs because i tried to find them online and they are a discounted item .
if i ever get this car fixed i am only going to use it as a back up , and now i need to go find another car i love my fords but this has just been hell !!
and still don't know if what i am doing is going to fix the codes . i do have extract tools but they wont work as long as the threader point is in there i need to drill it down flat if not i might just have to go and buy a new manifold .. any way wish me luck
 

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