1999 expedition

[lifewitlooie]

looking for help.. my friends expedition is having problems.. check engine light came on. pulled codes. forgot number code . said engine is running lean. changed 02 sensor. engline light went away. came back on 2 days later. mass air flow sensor maybe?? need help thanks or a link to better info i could search through... maybe a flow chart or something for a lean running engine thanks

[colo86GN]

I have an 01 expedition. Just a thought, after you changed the o2 sensor did you reset the computer? Try pulling the battery and putting it back on, that usually works for me. Hope that helps!

[Stan's 04]

I have a 99 expedition lite on system running lean look at the vacum lines by the pcv valve the always crack on the bends , make sure you take them off and look really good .

[mschn99]

Originally Posted by Stan's 04

I have a 99 expedition lite on system running lean look at the vacum lines by the pcv valve the always crack on the bends , make sure you take them off and look really good .

particularly the one that runs to the PCV valve...its a VERY common problem.....it needs to be tested for vacume leaks...