i'm stuck and pulling my hair out p0171 and p0174 | Ford Explorer Forums - Serious Explorations

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

army1959

Member
Joined
June 23, 2018
Messages
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City, State
dallas tx
Year, Model & Trim Level
1998 ford explorer
1998 ford explore 4.0L ohv 6cyl
so for the last 3 months i keep getting these codes every 5 to 7 days the p0174 code has not come back once i changed the fuel filter ;
the next thing i did was try to clean the mas but it was original part and it would not come clean so i replaced it as well as the metal hosing , original had a small crack
that lasted 2 weeks , and again p0171 showed back up so i did a smoke test no leaks , but to be on the safe side i changed the vacuum lines i could tell they were getting bad , 7 days latter p0171 so i changed the pcv valve and hose good to go, 5 days latter you guessed it p0171 , ok so took it in got a fuel pressure check it passed .
next i did a tune up new plugs wires and coil pack , the old one was original and i could see signs of wear on it , good to go for about 4 days and here it comes again p0171
did another 4 smoke tests , nothing the last smoke test i let it run for 45 minutes got under the car could not find any thing put it in the tail pipe to see if there were any leaks in the exhaust manifold nothing , today i pulled out the air idle control and cleaned it ,it needs to be replace as its the original . but no codes i drove around for about 25 miles checked the im and it was green across the board . but my OBD2 Scanner
it showing pending code of you guessed p0171 , i'm about ready to put the explorer up for adoption
so any help would be great please i don't want my ford in foster care
 



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I'm totally shooting from the hip here...but did you look at the DPFE Sensor and the attached hoses?

I know you said you did a smoke test and that should find any leaks...but maybe something is just slightly cracked somewhere and would only show when sucking air in (ex. spraying carb cleaner around a running engine to see if there is any change in the RPM's (indicative of the carb cleaner being sucked in and increasing the RPM's)).

I have the OHV engine - here's me spraying carb cleaner YouTube around my DPFE Sensor searching for where I was getting a vacuum leak.

The day earlier, I had changed my DPFE sensor because the hose on one end of it...completely burned off. As the lose hose was broke underneath, the hot gases coming out of the hose, burned a hold in the underside of the plenum housing...and I could not see it at all. I didn't have the benefit of a smoke machine...so carb cleaner it was.

Anyway, not trying to lead you down a rabbit hole...but just passing along my own experience with the same code years ago. Vacuum leaks are a PITA to chase down.

Edit - I know that spraying Carb Cleaner around a running engine is sorta dangerous...so spray very sparingly!
 






PO 171 AND 174 = Leaky intake plenum gaskets

Smoke test or not I have $5 says your plenum O rings need to be replaced, upper and lower

There is not a 97-01 SOHC engine in existence that does not need new O rings....ethanol in our fuel /time / miles destroys the factory intake O rings

It is not a hard or expensive job, it does require a couple of special tools to make things go easier
171 and 174 + 4.0 = intake gaskets
 






I'm totally shooting from the hip here...but did you look at the DPFE Sensor and the attached hoses?

I know you said you did a smoke test and that should find any leaks...but maybe something is just slightly cracked somewhere and would only show when sucking air in (ex. spraying carb cleaner around a running engine to see if there is any change in the RPM's (indicative of the carb cleaner being sucked in and increasing the RPM's)).

I have the OHV engine - here's me spraying carb cleaner YouTube around my DPFE Sensor searching for where I was getting a vacuum leak.

The day earlier, I had changed my DPFE sensor because the hose on one end of it...completely burned off. As the lose hose was broke underneath, the hot gases coming out of the hose, burned a hold in the underside of the plenum housing...and I could not see it at all. I didn't have the benefit of a smoke machine...so carb cleaner it was.

Anyway, not trying to lead you down a rabbit hole...but just passing along my own experience with the same code years ago. Vacuum leaks are a PITA to chase down.

Edit - I know that spraying Carb Cleaner around a running engine is sorta dangerous...so spray very sparingly!




i did the carb cleaner ever sensor has been checked i did a smoke test on every line individually and no joy i did soppy water . foam spray etc
and its not showing the p0401 code . the fuel pump checks out as well the only thing i can think of to do and really don't want to is the manifold
, i keep thinking it might be the o2 sensor on bank 2, bank 1 sensor 1 was changed out last year and thanks for your answer if you can think of any thing else please let me know
 






PO 171 AND 174 = Leaky intake plenum gaskets

Smoke test or not I have $5 says your plenum O rings need to be replaced, upper and lower

There is not a 97-01 SOHC engine in existence that does not need new O rings....ethanol in our fuel /time / miles destroys the factory intake O rings

It is not a hard or expensive job, it does require a couple of special tools to make things go easier
171 and 174 + 4.0 = intake gaskets
PO 171 AND 174 = Leaky intake plenum gaskets

Smoke test or not I have $5 says your plenum O rings need to be replaced, upper and lower

There is not a 97-01 SOHC engine in existence that does not need new O rings....ethanol in our fuel /time / miles destroys the factory intake O rings

It is not a hard or expensive job, it does require a couple of special tools to make things go easier
171 and 174 + 4.0 = intake gaskets


so you were right the gasket was bad . but here is my question i can not seem to find that gasket the keep say that this is the gasket for it second photo and i have this part its thick so do i even need the gasket 3rd photo and the only rubber ones i have look like this . i tried searching for plenum O rings but cant seem to find any i tried searching for
Fuel Injection Plenum Gasket
with no luck so does it need that gasket or do the plastic ones fit in there some how because there were none in that bottom part at all just that flat gasket . can i just get by with rtv ? not sure what i am doing here thanks in advance
 

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...again, I have no clue if this might help...

Ford Explorer 4 0L SOHC Upper and Lower Intake Gaskets Part 1

Ford Explorer 4 0L Upper and Lower Intake Gaskets Part 2


There's also LOTS of threads related to a plenum gasket job up here.

I replaced my upper plenum gasket (s) on my OHV engine about 8 years ago...but my gasket kit seemed a whole lot different than the SOHC engine (rightly so).


thanks the videos were helpful what i did was while searching i looked at the photos instead of the description searched for a 1998 ford ranger and found the gasket set i needed , and it fit perfect . i find it odd that that i could not find one for the explorer , any way i am still putting it back together
i should have it done by tomorrow thanks for all your help
 

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YOU HAVE A OHV 4.0

not a SOHC!!!!!!!!!!!!!!!!!!!! Your engine is a pushrod 4.0
The Single Overhead Cam uses totally different gaskets.

When you search for your explorer gaskets use the OHV engine
 






YOU HAVE A OHV 4.0

not a SOHC!!!!!!!!!!!!!!!!!!!! Your engine is a pushrod 4.0
The Single Overhead Cam uses totally different gaskets.

When you search for your explorer gaskets use the OHV engine

thanks for that i got the one for a ford ranger and it fits and auto zone and o riley's auto parts don't really give me that choice they keep telling me that the parts for the sohc fit . not sure if i should keep going or not i have it half way put back together , tx heat only gives me a few hours in the morning to work on it . and thanks again for that
 






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

171_121133_350000000.jpg


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
 






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

View attachment 318675

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
thanks that's what i did i went with the ranger one do i need to use rtv with this
 
























i finally got it done i ended up doing it twice so far ,now it runs rougher than before , i get p0174 code i made sure all the fuel injectors were seated checked for leaks none i cleaned them, i had to disconnect the egr tube from the mushroom cap i could not get it out of the plastic housing , tighten
it back down to 15 lb i replaced vacuum lines , new gasket did a leak test no leaks and i now get a burning smell cant tell were that is coming from ..
i had to change out the DPFE sensor and put new lines on them , i have tripled checked the plug wires to make sure they were in the right spot
on the coil pack , checked all the fluids , don't have any leaks from there no exhaust leaks . and the weirdest thing is if i turn on the ac it runs really bad , o2 sensor is good on booth banks , and the car was running good before the leak in the plenum .and the weirdest thing is if i turn the ac on it runs really really rough , i think ill just break down and take it to a shop . any help would be great
 






well i still am having problems so i found this guys post its got a great guideline and i am going to try it one more time
 






yes it must be done correctly, sorry to hear about your troubles!
Good time to replace plugs and wires
Good time to replace injector O rings and plastic caps/seats
excellent time to replace thermostat and housing and timing chain tensioners (drivers side especially since thermostat housing and intake must be removed to access)
Those EGR tubes must be replaced with high heat EGR compatible lines or they will melt

The intake plenums should be carefully inspected while they are off for any cracks, chips or deformities

Im 30 miles from Canada, way far from Dallas otherwise I would be happy to help
 






thanks plugs and wires i all ready did and O rings thermostat and new housing the old housing was rusted out and had holes in it .. the The intake plenum had no signs of any damage i just cleaned it up with carb spray and a nylon brush i got new studs and nuts . i want to replace the injectors
but i can not find ,,any one that has a full set of 6 and i don't want to mix and match them , i have changed many a gasket over the years and never had this many problems , the egr tub seams to be fine and looks like it has already been replaced , by previous owner . its been a great car over the last 4 years never any thing major done to it , i guess its just that time for all the failures . well thanks for your help
 






Injector o rings fixed my 71 and 74 3 years ago and no light

I have a fuel injector machine in my shop that has beakers so you can see the flow and spray pattern so I can rebuild my own there's a special tool to remove to plastic spray tips I ditched the plastic injectors for the metal wide body type that you typical see in older fomoco vehicles
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





Injector o rings fixed my 71 and 74 3 years ago and no light

I have a fuel injector machine in my shop that has beakers so you can see the flow and spray pattern so I can rebuild my own there's a special tool to remove to plastic spray tips I ditched the plastic injectors for the metal wide body type that you typical see in older fomoco vehicles



this is my oem number for the ones i have now
0280155735
but the only ones i can find are these
0280155734
and i am just wondering if they would work
also i found out the studs have been discontinued so not sure what to do about that . the replacement studs do not have the flange on them
the flange on the stud helps hold down the fuel bar and set flush in the fuel bar and not sure if the replacement ones will work
any help would be great thanks
 






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