So I picked up a 2006 screw about 4 years ago. The motor was missing and running bad so I took it to the dealer. They wanted around 4 grand to work on the motor so I found a new test motor to put in.

Now on to the test motor.

We inspected the motor by pulling the valve covers and pan. Looked great no corrosion no rust clean as can be. Looked new. So we get the motor in and truck runs the same as the old motor. Feels like missing of passenger side. back to the dealer and a 400 compression test. motor is down on compression on the whole passenger side. they want 7500 for a new motor. I take it to the guy I got the motor from who repeats compression test says motor is perfect its the cats. He cuts off right cat and it runs the same. We get in a huge fight and now I have to either sue or live with the motor.

I pulled the intake and look into the intake valves. The front cylinder intake valve has a C clip around it preventing it from closing. I pull it our and engine runs . Decent power and smooth. I drive the truck for around 3000 miles. It sounds terrible and power is down but it drives so I leave it alone.

One night in a rain storm throws a misfire code no power and shakes like hell. I limp it back to my shop and park it.

Fast forward a few times messing with it and this is what I know now.

The left cam caps have scoring but it could be from debris when I pulled the valve cover. It starts up and runs great has decent power for the 1st 10 minutes. After that the motor shakes like it is missing and has no power. It throws no codes at all unless you drive it. Then it throws a random transmission code. I would love to just take it to a 5.4 3v expert but the dealer is not the place I would choose. Any ideas?

Should I just get a reman 5.4 or look for a used running one. I have some money coming that I can use to get my truck back on the road I just don't know if I should try to fix this motor or start over.

OH btw the motor is out of a 2009 f150 with the redesigned heads and plugs.

PLEASE HELP!!!

 

Well you say you found a "C"clip in cyl #1....are you sure it was a "C' clip or was it half of the valve seat? If the valve seat broke and a piece is floating around in and out of the intake manifold bouncing into one cyl and then another you can get a random missfire, I've seen this happen. Seems odd that the second engine is doing the same thing the original engine did. Did you install the original engines intake manifold on the new engine and if so did you make sure there was no debris in the intake manifold?

 

No it was a C shaped piece of plastic. I had switch out the manifold a few times. I double checked everything before installing the new one I bought. I wish it was that easy. I think the only similarity between the original engine and its replacement is it was not running on all cylinders. I should have never replaced the 1st motor. It really just needed VCT everything and a good cleaning. The motor that is it something is wrong with it. I just cant figure out what it is. Still looking for a guru to drop it off at and tell me what to do next.

 

Someone who did an 09 swap into a 04-08 had issues on here.

 

Yeah, can an 09 5.4 just be dropped in without changing anything at all?

 

I don't think so, they guy had a tough time. There may had been another issue though, I'm gonna check

 

Well I believe that was me. I posted about the swap and it was a long thread. There is another guy who did it with no issues at all. basically you just need to swap intake, fuel rail, injectors, and oil pan. Everything else lines up fine. I had this truck running good for a while but I believe something is wrong with my motor but I am not exactly sure. It is a nice piece of parking lot art right now and for the last year and 1/2.