Hey guys,

I'm new here and I hope somebody can point me in the right direction.

I have a 97 expedition 5.4. It's been running pretty rough lately and the engine light came on so I had Autozone throw it on the scanner. It turned out I needed to replace the MAFS and the o2 sensors. I did that yesterday morning and the engine light went off by itself and she was running pretty good for the rest of the day. I got in to go home from work and the same symptoms were back along with the light. It has a really rough idle and almost stalls out at stoplights, but it runs fine on the road/highways. (maybe a little power loss)

Like I said, i appreciate any help someone could send my way.

 

I would get autozone to pull the codes again then post them on the site. I can etter help you then.

 

OK I got some codes.

P1151---Fuel air metering
P0171---System 2 lean (bank1)
P0174---System 2 lean (bank2)

I don't know my way around engines that good but I'm pretty mechanically inclined when pointed in the right direction. What would be a good source for pics/diagrams of the component locations?
Thanks for the help.

 

The lean codes are caused by either a vacuum leak or intake leak and sometimes low fuel pressure. Have someone with a good ear listen around the engine while it is running for a leak.

 

I had the exact same issue, same car also.... lean codes, rough idle, good on road, stalling at a light.
replaced all 4 Co2 sensors...cleaned MAF... replaced all vacuum lines...
Turned out to be a hole in the back end of the PVC hose elbow... u can hear it but cant see it.... the rubber 90 seemed to be baked by the heat at the top center back behind the ?idle control?. Replaced the PVC valve and hose...runs good now. Probably only needed the rubber 90 piece...
Wish I would have known this before the costs of those sensors.

 

The PCV tube is fairly common on those, right where it meets at the back of the intake manifold.