HELP!! My '98 Expedition has been idling really rough the last couple of days and the check engine light came on. I took the truck to Autozone and got the codes po171 and po174. They told me that it was probably the fuel filter or the Mass Air Flow Sensor. I had the fuel filter replaced and that didn't help at all. So then I found this forum and found that it is probably the pvc valve. Here is where the problem comes in. My husband went and got the part from Autozone but he can't figure out where the part is in my truck.

I downloaded the instructions from one of the posts on this forum but he still can't figure it out. Can someone tell me, if I use the throttle body as a reference point... where is the pcv valve in relation to this??? Please help!!!

 

Looking at the throttle body, the PVC valve is located in the top of the left side valve cover of the engine. It is a little diffulcult to see without looking close. Hope this helps.

 

Check the vacuum line while you are there that connects to it.

 

Thanks for all your help. We found it. It is definitely the culprit. When I felt it I felt it was in very bad shape and had a hole in it. Then I did the stupidest thing...I pulled it in half. I then spent a few hours trying to get it off. The space is so tight that I thought I could do it better than my husband. Let this be a warning...Do Not use a razor blade to try to cut it off. I practically cut the end of my finger off. My husband finally got it off. We then found out that you have to get the part from the dealership. Autozone and O'Reilly's do not carry the part.