Maulerman

Could be rod knock.

Braidyn23

Need help with finding the problem with a 04 f150 xlt 4x4 5.4 new body not old 5.4, has a idle issue with shaking along with when reaching speeds around 65-80 or more it tends to shake when accelerating, changed spark plugs, coil packs, o2 sensors, and injectors, and have checked the mass airflow sensor, not sure if it is a vacuum leak but have tried to check with brake cleaner and no change with the engine idle. could it be the lcv valve that can cause a issue like this?

Creek13

I have the same things going on so I've replace everything that can be replace. I felt that I power feeling long enough so I had my cats cut off they were plugged with all the raw fuel It runs much better. I've ordered a set of long tube ceramic coated headers haven't got them yet but soon after I install them I'll get my computer flashed wipe all the junk off and try it again

LEN671

So you took your Cats completely off or just replaced them?

What did you do about the O2 Sensors?

LEN671

Reason I ask is because I am having that same problem. I replaced all 8 spark plugs, boots, COPs, and did an Oil Change. Problem is still there.

Creek13

I did not and won't replace the cats, the sensors on the cats are just telling the system are there to say they are working or not so I do have a lite on but I will have it deleted of the computer. It's a 10 year old truck that's pulled a enclosed trailer since day 1. I'm going to make it pull

Creek13

There's another thought I have, when I replaced my fuel filter clean gas came out on one side and extremely nasty gas came out the other. I'm guilty of running 10% ethical fuel which I'll never do again so if my filter looks like that I'd bet my gas tank is full of it. I'm going to pull my bed off and pull the fuel pump and see what it looks like, I've heard there's a filter on it and I bet it's trashed. My truck still acts like it's running out of fuel at 2400 to 3500 rpms and a hill kills it trying to get up

LEN671

So then you would have to send your computer to Ford to do that or you have a program and/or a device that can do it for you?

LEN671

I am kind of confused with this post. Haha. So you did get the cats cut off, and you also decided to not replace them with new ones? Basically you have no more cats on the truck.

Creek13

That's correct. It does run better but not fixed. I still have to get the headers put I and get reprogrammed. I think my gas tank has trash in it , I've been changing fuel filters often and within a week it's got trash on one side and clear fuel on the other so I'd bet the filter on the fuel pump is plugged at 2500-3000 rpms it feels like it's not getting enough fuel but runs ok at lower rpm