Rough idle? P0171, P0174? Here's what you need to check first!!!

[Lightnig]

Yay, finally got this accomplished. Thanks for the heads up on the hose.

I had no end of grief getting this done myself, mostly just finding the ends of that bloody hose.

For those of you that may be having difficulty locating both ends of the hose:


The top right is on the back of the Throttle Body underneath the cowl against the firewall. My fat hand had to go over top of the hose, it simply would not go under.

The bottom left is the PCV itself, where it is inserted into the Right (passenger) side valve cover.

A close up of each end:


My hose did not come apart in one piece. The hose on the back side ripped (it was still soft and flexible), and the tube came apart in 4 pieces - one piece out of the 90 disappeared entirely. Good thing darn thing that I had the replacement on hand.

By the way, the one my dealership sold me was labelled F75Z-6C324-JA and fit properly.




Definitely smoothed out the idle, and no more P0171 or P0174 codes yet. I guess I will know later this week if this solved the problem in the long run.

 

[peterbs]

p0171 p0174 PCV 90 elbow deformed w/ hole

I had both codes p0171 and p0174 on my 99 expedition 5.4 liter. Cleaned my MAF, but codes came on again. Ordered the non heated PCV hose, not realizing I had the one with a Y right off the PCV valve. I should have listened for the noise first and diagnosed by leaving the engine running and wiggling the hose around. If I had, I would have found the obvious huge hole on the inside of the 90 elbow attached to the PCV valve. Went to autoz##e and bought a $6 PCV elbow, 30 seconds later I was done. I little bit of wigglin hoses would have saved me the expense of buying the part I didn't need (look for it on ebay). If you have these codes, rule out hte obvious easy repairs first,......locate your PCV valve, start your engine and feel around for a leak, depending on it's size, wiggle the 90 elbow hooked on to the PCV, if it's bad you will will hear an obvious change in the hissing sound. I cleared the codes and because of the extremely poor condition of the elbow,that I fixed it. I will uprate if the codes come back on.

 

[scottsbro23]

Yay, finally got this accomplished. Thanks for the heads up on the hose.

I had no end of grief getting this done myself, mostly just finding the ends of that bloody hose.

For those of you that may be having difficulty locating both ends of the hose:


The top right is on the back of the Throttle Body underneath the cowl against the firewall. My fat hand had to go over top of the hose, it simply would not go under.

The bottom left is the PCV itself, where it is inserted into the Right (passenger) side valve cover.

A close up of each end:


My hose did not come apart in one piece. The hose on the back side ripped (it was still soft and flexible), and the tube came apart in 4 pieces - one piece out of the 90 disappeared entirely. Good thing darn thing that I had the replacement on hand.

By the way, the one my dealership sold me was labelled F75Z-6C324-JA and fit properly.




Definitely smoothed out the idle, and no more P0171 or P0174 codes yet. I guess I will know later this week if this solved the problem in the long run.

My wifes 03 Eddie B (5.4) was having the same issues but no codes. I removed the same hose as above. Except it is different, starts and ends at the same spots but has a "Y" in the middle that plugs into the side of the manifold port that has coolant lines running thru the port as well. Hose portion tore in half when I was removing it from the port. The 90 deg. elbow was deteriorated and had a crack. Auto parts store said it was a Ford Factory part (complete hose assy)..hell with that, bought an elbow and cut a section of tube to replace the split section. Then removed and cleaned the Throttle body and IAC. Went to buy the gaskets for IAC and Throttle body, computer does not show the correct throttle body gasket for the 03 5.4L. I Installed a throttle body spacer on my sons 99 4.6L a couple weeks ago...and the gaskets are the same for both. Ford claims they stopped using this gasket in 2001. NOPE... So if you do this ask for a 99' 4.6 or 5.4 throttle body gasket. She purrs like a kitten now...(gotta unplug the neg on the battery as stated in previous posts)

 

[kgreenjinx]

You guys Rock!!! I have been chasing this CEL for quite some time. getting a 171 code and that's all. 2003 expy with 5.4. As scotts bro said 03 is slightly different than what has been posted on here but same place. Felt around the hose and slowly moved it and heard a huge hiss. The lines Y off and there is a straight rubber nipple that is leaking on mine. No hissing unless you move it. You guys are a god send. Hopefully get mileage back up to 15. Now off to the auto parts store to find a replacement "boot" I need to go to town anyways to get a 30mm, 21mm and 19mm impact sockets for air coil conversion, 3.5/2.5 spacer lift this weekend. Have it tore somewhat apart so hopefully can post some pictures.

 

[sonofalver]

this post saved my butt. 6.99 rubber boot was the fix

 

[Berg]

same 2 codes everybody is mentioning. mine had the boot melted closed ! trying to get it off it broke and half is off and half is sill on. it seems as if its glued on or something !!!!! im attempting to get it off piece by piece but its very tight back there. truck out of commission for 4 days now.i get off work its almost dark

 

[Berg]

def was the elbow.changed it and no more codes and smooth idle.wife drove it and said it felt like it had more power runs with less noise.keep in mind she never knew the truck was out of commision or had a issue...im guessing since mine was melted closed it was happening over time.i wonder it it was letting in less and less air making everything unbalanced thus creating a rough idle... anybody know if this could have been true?

well she runs good as new.i did clean out the MAF like 3 times before I found out it was a issue with the elbow.maybe that helped too.

 

[glen615]

Hi All

I hope I a can get a little help on what my issue with my 2001 Expedition might be. This is 5.4 V8 2x4. The check engine is on and throwing P0171 and P0174 codes. Both banks I understand from my research. So I have replaced the PCV (the whole assembly, hose, and elbow) since it came together from the dealer. I also replaced the plugs with motorcraft plugs and also replaced all coils and boots. One of the hardest automotive repairs I've ever done). I have also cleaned the MAF, and IAC, as well as replaced the IAC gasket.
So I think the initial troubleshooting can be considered completed. So why am I still getting the damned codes?? I'm at a lost, none of the coil cables seemed melted or otherwise damaged and I can't think of where else to check. I'm hoping the you guys might have some insight

Thank you very much in advance

 

[hwy73]

I believe those codes have to be cleared after the repairs are made. Either with a code reader plugged into the OBDII port or by disconnecting the battery for a period of time to clear the computers memory.

 

[glen615]

I had cleared my codes when I completed the work and the truck seemed to run smoothly but about 80 miles later it wanted stall. It tends to happend when slowly accelerating from a stop.