So I have the P0171 and P0174 error code in my 1998 4.2l spi and so far I have changed the pcv valve, fuel filter, spark plugs, cleaned the mass airflow sensor with the proper cleaner. I have checked the hose that comes out of the pcv valve for holes and when the truck is on the pcv valve hold a vacuum. Today on my trip too auto zone the guy there suggested using the spray that cleans the MAF sensor on the o2 sensors to see if they just need to be cleaned. I was able to get the post catalytic converter out and lightly sprayed them down. I wasnt able to get the other 2 because of the tight space, I just read a thread on here about going through the wheel well and I will get them out tomorrow and check them. Oh and my truck has 180,000 miles on it.

So does anyone have any suggestions on what I could do next to try and fix these error codes. I am also getting horrible mpg's which im assuming is from the bad fuel and air mixture.

Thanks for the help.

 

You probably need new intake gaskets, bushings, and isolator bolts. You have a major vacuum leak that you haven't found yet.

If you have 180k and are going to pull the front O2's, replace them. Use only Bosch or Motorcraft.

 

I forgot to mention that when I shut off the truck there is a quite noticeable hissing sound, that I assumed was just the AC but now that I think about it it could be what you said. On a scale of 1 to 10 how hard would it be for me to replace the gasket myself.

Thanks for the quick response I really appreciate it.

 

Read this it is very helpful.
http://sites.google.com/site/fordf15...p0174fix/Home/

That should help you decide.

I fought mine for a long time and finally bit the bullet---it is SO much smoother!

 

The link says the site is not found.

Edit: nvm I go it to work

That site is delectable!!!! thank you so much


For the people that are just reading:
http://sites.google.com/site/fordf15...P0171P0174-Fix

 

Let me try again, maybe I copied ir wrong.

 

Gotta do some more checking

 

If my copy "skills" aren't working you can go to the V-6 forum and look up my post "Plenum gaskets and Isolator bolts"

But try the link here:
#4 05-31-2010, 02:03 PM
jgger
Senior Member Join Date: Oct 2009
Location: corona ca
Vehicle: 2003 ford f150
Posts: 465

There is already a good link...http://sites.google.com/site/fordf15...p0174fix/Home/
Just wondered if there was something to keep an eye on while it's under the knife.
I would add ---check the grommets on the IMRC while you are in there for anybody else doing this. Thist is the BEST EVER look you will get at that baby!!!

Look up the post, I can open it from there, but can't seem to get it to work here.

 

Good I was freaking out b/c it would work from 2 other places but not in this thread!

Glad you got it.

 

Thanks for all the help guys, I will do this tomorrow and we'll see what happens.

 

The Isolator bolts might be a dealer only item, might want to check that out before you open it up. The gaskets are most auto parts stores.

Good luck and post your results.

One more thing to check before you dive in is the vacuum resivor behind the battery and the lines to and from it.

 

You can't drag a link to copy it - you have to right click it. If you drag it, it becomes truncated with the ... in the middle.

My local Ford dealer did this for me for less than $400.

 

Well he got to it in spite of all my excelent computer work! ha ha

He has it right in post #5 above.

 

I will not be doing this now, my Mother wants me to take it to a mechanic bc its a big part of the engine.

Thanks for all the help guys.

 

Nah! it's only about 39 bolts tops! jk
Let us know how it turns out.