Engine Shaking Bad Stable RPM's

[S7rikerz]

For the life of me I cannot figure out what is wrong with my expedition.

This problem has been going on for about a month now, the vehicle sat for 2 weeks when I went away on vacation I forgot to leave the keys so my mother in law could start it up while I was away.

When I got back, I started it and the engine was shaking for a good 20 minutes the RPM's would flutter a little then the check engine light came on, so I took it to Auto Zone, they got the code and it came back saying 2 of my plugs were miss firing, I changed all 8 plugs with brand new ones, and reset the check engine light.

The shaking didn't stop, so I have been driving it around trying to get the check engine light to come on so I can finally find out what is wrong with my vehicle, but after a month of driving it the check engine light is not coming on, and the shaking is getting very bad.


2003, Ford Expedition, 5.4 V8 178,834 Miles

( I have checked the engine mounts already and they are good )

Engine Shaking in Drive, also While in Idle, shaking gets worse around 20MPH, stops at 25-40, Gets bad at 45-60, cant drive it at 70+ I am scared to with how bad it shakes.

RPM's do not fluctuate at all they are always consistent,

I can feel when I am giving it gas that it is having a lack of power ( this does not happen all the time )

Sometimes Rarely, I will hear a kinda one time clank noise it is loud enough to hear it inside the car when that happens I can feel the vehicle jump forward ( not literally ) and I have all my power back, this does not last long.

Any Ideas?

 

[MikeA]

The problem can be numerous things, from vacuum leaks, to egr, sensors, wiring, timing, etc.

Best to check the things that don't cost money, like physically check for vacuum leaks from intake to all the rubber vacuum lines, when i say physically check, you need to grab vacuum lines, sqeeze them,make sure there secured, not loose, feel along for leaks.

Do a thorough job checking for leaks. Can not stress this enough!

If no leaks, next thing is to start checking sensors with ohm/volt meter, can find how to check, by searching internet for each sensor.

Pull spark plugs, looking for maybe fouled plugs etc.

I am tossing some stuff you can do for free, if nothing else, atleast confirm that theses things are not the problem, before you have to start dumping money into parts that may or may not fix problem.

 

[docraymund]

Start by doing a cylinder balance test so you can zero in on the problem cylinder/s.

 

[Clemson82]

Have you tried putting some dry gas in?

 

[S7rikerz]

I will try the recommendations that I got in this thread over the weekend and report back on if I have found anything.

 

[jpritter]

Were the codes a P030x code? If you remember which cylinders were throwing the codes (P0301 is cylinder 1, P0308 is 8), try swapping those coil packs with ones that did not throw a code. If the packs are the issue, and the CEL comes back on, it should be different that the original codes.

I got a couple those codes in the past, while my 06 was under an extended warranty. The dealer replaced the plugs and both coil packs and that fixed it. Recently I've had the same problem pop up again. I know it wasn't plugs, so I swapped coil packs between one of the replaced packs and the one that threw the code. After a short time the CEL reset itself and hasn't come back on since. I'm guessing that if a code comes back, it will be a the one where I swapped the pack from the one the threw the code.