Good morning.

I have a 2005 F-150 SCREW cab 4.6L with 216,000 miles on her.

I had a check engine light come on the other day with the following codes. P0316 (Misfire shortly after start up) and a persistent P0305 (#5 misfire)

So I replaced the coil and spark plug on #5, reset the code, and the motor still runs rough at idle and eventually spit out another P0305. Then I replaced the fuel injector with no difference in results. I OHM'd out the old injector and its still good with a resistance reading of 13 ohms.

Then I did a compression check....read about 40 PSI on #5 cylinder (need a minimum of 90psi for combustion). In haste, I did not check other cylinders compression nor did I isolate whether the rings or bad by putting some oil in the spark plug hole and taking another compression reading.

What else should I check?

Are 4.6L motor swaps pretty easy to do? Where can I get a decent priced long block from?

Also.....if I swap out the long block and keep the computer and all the components, will I have to reprogram the computer for any reason?

Thanks a million guys.

Cliff