Hi guys,

First time poster. I have 2006 Expedition with 5.4. About a month ago, I noticed a bit of hesitation when accelerating at about 45 mph on a hill, I had hit the gas a little harder than normal. Didn't think much of it. About a week ago, I noticed it again. This time the CIL came on, blinked about a minute, and went off. This happened once more this week. All of this was still when the vehicle was accelerating pretty hard (merging onto freeway up a hill).

Got a code scanner and got P0306 and P0174. I cleaned the MAF and checked (but didn't replace) the COP on #6. Went out and tested, and problem was the same. This time I got a P0304, an P0305, and finally a P0300 at various times. When not under real heavy load, the truck runs normal, even under normal acceleration.

Haven't done much to it yet besides replace the air filter after the first occurrence a month ago and cleaned the MAF. Could it be a bad coil? I'm inclined to replace all 8 of them if there's a good chance that could be the problem. I did run a couple of bouts of Techron through the fuel system, but that didn't seem to help. I don't see any obvious vacuum leaks. I have 65k on the vehicle and haven't replaced the fuel filter. Could that be a potential cause? I'm no mechanic but I'm fairly mechanically inclined.

Any help is appreciated!!!

 

When you replaced your air filter did you install a K&N type filter? You may have over oiled it if you did, it's a fairly common problem

 

Thanks for the quick reply! I didn't use K&N, just the standard Fram air filter.

 

Okay, sorry, no help here. Good luck with it.

 

All the codes are misfire related codes with the exception of PO174 which is a lean code bank 2.

As far as the misfire codes it may be a good time to change to change all COP's and plugs, you did not state how many miles on you Expy but the plugs are recommended at 100K. However I change them before 100K but that's me.

The lean code could be a vacuum leak after the MAF sensor, so would make sure that you don't have a vacuum leak before suspecting an O2 sensor.

 

This could be a sign of an upcoming fuel pump failure. You might want to test the pressure just to rule it out.