Rookie DIY'er here so please bear with me. 04 Expy Eddie Bauer (5.4L) was idling rough, killing and surging. Bought a scanner and pulled four codes: P0171, P0174, and two others that I cant find my note paper now (when I read online these four codes were apparently common together ??)


Anyway - I found a crack in the rubber hose near pcv valve. When I went to autozone dude sold me a new pcv valve and the rubber elbow and some hard rubber hose to use. HOWEVER, I really dont think I had an elbow originally on there (Is that possible?). I had the hard plastic tube with rubber hosing on both ends and it went pretty straight from the pcv valve to the other side. When I went to reinstall using the elbow, the hard plastic tubing aimed away from the other nipple I needed to hook to. It would either be sticking way up or way out near the throttle cable based on the angle of the elbow... didnt look right.

Is it possible that I did not have an elbow to start with? Also, the new elbow does not fit snug onto the pcv valve at all. In the end, I just bypassed the elbow and the plastic tube altogether. I ran a single piece of hard rubber hose (very hard but flexible) and hooked one end on the pcv valve nipple and other end on the other side. HOW BAD DID I SCREW UP ?

I also pulled off the throttle body and it was a disaster. I cleaned it thoroughly and reinstalled. The idle problem seems to be corrected, at least for now. For a day and 1/2 the Check Engine was off but it came back on today and Im getting code P0171 again. After doing the job sunday, there were no codes at all.

Do I need to reassess the pcv situation? What else?

Thanks, sorry for long post.

 

I have the same 04, Eddie Bauer 5.4 with the 0171, 0174 codes. So far I've sprayed the MAF sensor with electronic cleaner, haven't gotten to checking the pcv hoses and fittings yet because of the extreme cold (don't want to cause anymore damage trying to pull on cold plastic hoses. But I've also done some snooping and the fuel filter also falls in this group of possible remedies. I've watched a bunch of you tube videos and to solve this problem they had to go so far as to smoke test the engine to find vacuum leaks. That one happened to have a intake gasket leaking. I haven't got any other problems than the check engine light so far.

 

These hoses are difficult to describe, and they can vary from year to year. Pictures save a lot of typing
And my get more/better responses.

 

That's why its a good idea to take a look at your scan tools freeze frame data. If the P0171 and/or P0174 is the code that tripped the CEL, the freeze frame data will tell what was going on at the time the code was set.

If the freeze frame shows the engine was at light throttle and low rpm when the code set, its more than likely you have a vacuum leak. (A tiny little vacuum leak will have a significant impact when the throttle is closed, and will have a negligent impact when the BIG old throttle is wide open.)

If freeze frame data shows the engine was at heavy throttle and higher rpm when the code set, it is more than likely that you have a fuel supply problem. (A weak fuel pump or plugged fuel filter may be able to keep the PCM satisfied when the fuel needs are low, but can't keep up when the BIG old throttle is wide open.)

 

My OBDII doesn't go that in-depth, all it will do is read the codes. But since we just bought it, the fuel filter will get changed.