1997 Expedition 4WD 5.4L Running like crap...

[duckyman]

Several days ago, my normally great running '97 Expy 4WD 5.4 started to miss and stutter on acceleration. Having experienced bad coils in the past, I put my code reader on and it said cyl.#2 was misfiring, so I changed out the coil. It seemed to run better, but not perfect. Also, replaced the fuel canister purge hose because it had a small split. Next morning, I drove to town and it was running like crap. I ran the code reader again and came up with (Cyl.#2 Misfire), P0304(Cyl.#4 Misfire), and P0171(Bank 1 Too Lean). I also noticed a very minor noise from the right rear catalytic converter that sounded like an exhaust leak or baffle rattling. Next morning, when I started it, I crawled under and it was blowing visible exhaust (35 degrees outside temperature) from the cat. Here's my question: Can the hole in the cat cause such a large reduction in the operation of the engine and cause the error codes listed?? Thanks all!!

 

[00XTL]

An exhaust leak will not make the engine misfire in most cases. Now a clogged cat would and you would likely get codes for misfires on 4 or 8 depending on whether bank one is clogged or bank two. Whens the last time you replace the plugs? And another thing to keep in mind is a possible intake manifold leak?

 

[Ulver]

Was your coil on plug wet when you took it out?

Take those 1 and 4 spark plugs out and inspect them. If they're wet, look down in the spark plug hole and make sure you've dried it out good enough. If there's a coolant leak due to a bad upper intake manifold gasket then I believe coolant could run down the mating surface and pour down into the spark plug wells.

If not wet, and seem normal (which I'm expecting them to be a bit gray) then you may need to run a vacuum test, and check to see if you're leaking from the intake manifold or any component that's part of the intake (pcv valve hose, evap hose, etc.)