I bought an 04 F150 lariat. My problem is I bought it running on only bank 1, the previous owner spent $3,000.00 on new faster and plugs etc and it didn't change anything. I found that it had skipped a few teeth when they did the work on it so I re did all the timing so it was correct. That made no change to how it runs (like ****). So I did a compression test and found no compression on the drivers side (Bank 2). I removed the cylinder head to check for bent valves and it's all good, but I put a new head on anyways and put it all back together again. Still runs like **** and no difference at all. It starts up runs for a bit no codes and then starts to die out. Won't re start after it stalls out. Leave it for the day and starts up again and runs for about 2 - 3 mins and dies. I have a big headache trying to figure this thing out.

 

With the new head, I assume you now have good compression on that side? If not, likely a ring issue. Although I would think it is rare for four in a row to be bad at the same time (the op mentioned no compression on that bank). 5.4 I assume? Power to each coil? Fire at each plug? Fuel to each injector, and in the right sequence? If valve timing is correct and if compression is good, it has to be fuel delivery or ignition.

 

Well I put the new head on did the timing once again and started it up. Ran ok for about 30 seconds and then started acting up. The only reason I changed the head was because no compression and after running it with the new head and cheked everything I still had no compression. I contacted a ford mechanic that specializes in the 5.4L as he had an add posted on kijiji. He replied quickly with a phone call to me and we talked about my troubles. His final response was it sounds like you did everything perfectly now disconnect the exhaust on the drivers side and let's see if it's a plugged cat. I took off the exhaust and started it up and it runs great now. Plugged exhaust seems to cause a lot of headaches. I'm pretty sure that the guy I bought the truck from needed an exhaust repair not $3000 in engine repairs and I'm sure I didn't need to do all that work either. But what is done is done and tomorrow the truck will get the exhaust fixed.

 

Glad you discovered the issue. I certainly wasn't thinking about a plugged exhaust, but it makes perfect sense with the problem being only on one side. But why did that bank have no compression?

 

So the way it was explained to me makes sense. Normally air is pushed out the exhaust valve but if it can't get out the exhaust the air stays there. Now when the intake valves open there is air already in the cylinder so it can't suck any air in to build compression. There for there is no movement of air so how can you make compression?

 

So now I know!!!

 

Did you mean new phasers and plugs? Not sure what a "new faster and plugs" means. In any event, glad you got it running right.

 

Yes I meant phasers and plugs. Brain was all over the place and wasn't paying attention lol.