I recently purchased a 05' F150 5.4l with 188k and some engine problems. I do not full history of the truck, other than the previous owner said they were just driving it down the street and it suddenly started knocking so he had it towed to the garage. The garage then claimed it needed a new engine, but I'm not fully convinced yet.

It is running rough and has an obvious misfire and loud knocking / tapping noise. I checked the codes and came up with this list
P0303 - Cylinder 3 misfire
P0304 - Cylinder 4 misfire
P0300 - Random Misfire
P0345 - Camshaft Pos Sensor
P0352 - Ignition Coil B
P0353 - Ignition Coil D

I also did a KOEO test and got code:
P2006 - Intake manifold runner stuck closed

Any input on what I should be checking first? All the top codes seem like they would be related. Thanks.

 

I would start with new plugs and coils all around. If they're the original plugs - I would recommend having the dealer do them since they're likely to break, or unless you're willing to put alot of time and effort into CAREFULLY removing them (many threads in this forum regarding that).

You'd be hard pressed to find a 5.4 triton that hasn't experienced plug or coil issues at some point.

Next thing to check would be your Fuel Pump Sending Unit Relay. It's an exposed relay which sits near your fuel tank under the trunk, and will corrode out after a few years - I had one go on me, and it threw up several misfire and cam codes - as there wasn't adequate fuel getting through. It's a relatively cheap and quick fix.

 

i know on OBD1 Vehicles its best to start with the KOEO codes first as they could trip the KOER test... just a thought you may want to look into that first... but im not very knowledgeable about such things

i am going to guess that P0303, P0304, P0352, P0353 and P0300 are connected, as for the Cam Pos Sensor that could also be throwing out the miss fires...

 

Just a thought, to verify if your coil packs are bad swap the suspected ones with known good ones..not to hard to swap. recheck codes and continue from there. Note....ford has had problems with cam sensor due to cam walking. Ohh yea, dont forget to check battery connections..especially ground wire