I have a '99 Expedition with a 5.4. It has about 140,000 miles on it. The plugs, wires, and air filter were changed not to long back. It all of a sudden started popping thru the intake and developed a real bad miss. The motor revs fine ( just real rough with the miss). I checked the code and the ones below came up. I then cleared them started it(did not drive), and checked again. None came up.
P0401 EGR flow insufficient
P0171 System too lean (bank 1)
P0174 System too lean (bank 2)
P0302 Cylinder 2 misfire detected

Any help greatly appreciated.
Thanks,
Darren

 

I have never heard of this happening to a fuel injected engine. I know in carb'd engines can be caused by the timing being off.......but fuel injected....weird.

 

That's my problem I'm not good at all with electronics and fuel injection. I should add it has a real strong gas smell to it also.

 

Sounds like something is igniting the incoming fuel at the wrong time. A bad head gasket can produce an intake backfire and perhaps some electrical problems can fire a cylinder while the intake valve is open.

 

BTW, your 99 shouldn't have plug wires either, they have COP's