Ok I need some major help. I'm hoping someone out there has had this problem and knows what it is.

I have a 2006 F-150 4X4 5.4L V8 Flex with approximately 97K miles on it. All of a sudden the engine has started to jump and shudder under a light load, usually while just trying to maintain a speed, like cruise control on the freeway. I took it to the local Ford dealership and have spent major money replacing several parts just to leave and have it still doing it. I think they are onto guessing now at my expense. Here is what has been fixed so far.

They first told me it needed a tune up because it was misfiring. $500 on a tune up and it still doing it. Took it back and they said that two of my coil packs were going out and that I needed to replace them at another $500. Then I realized how easy these were to replace myself so to be proactive I ordered six more packs (Motorcraft OEM) and replaced all of them. Still doing it. Took it back and they said that they found a cracked spark plug, from the tune up they did, so they replaced it. Still did it. Took it back and they said that they found a broken exhaust valve spring on #5 which was covered by my warranty. Still doing it. Took it back and they ran pressure test and everything seemed normal in the cylinders but that the pre-cat pressure was high on the passenger side so they thought it was a pressure issue. They said that it was due to a clogged Cat on the passenger side (prob from the stuck open exhaust valve that was warranty but after three weeks of fighting they would not cover the cat). Even thou it was not throwing a code from the oxygen sensors.???? They wanted $1,800 for that. I took it to Midas and had a universal for our trucks put on and guess what....$550 later it's still doing it. Now it's back again and has been there for 10 days and they have no idea what's wrong with it. They run a test and send it to Ford and wait for Ford to tell them what to do then they do it and try again. Just got off the phone with them and they now said that they replaced the valve springs on #4, put everything back together and it's still doing it so they are waiting to hear back from Ford again.

Any ideas or comments from prior issues you got solved please let me know. I'm just tired of it being in the shop or getting it out just to go right back in. Thanks

 

My 06 is a flex fuel also and it was doing that too. I had the plugs changed with Motorcraft sp507 plugs and it cured it. I sure hope that they get yours fixed pretty soon. It is frustrating when someone else is working on my vehicles and don't really have a clue so they have to ask and wait for answers. That is one of the reasons I sold my 08 6.4l diesel. Everytime I took it in I had to wait on them to get answers back from ford and hoped that it fixed it. Good luck!

 

UPDATE: So Ford sent them a new list of test to do (I'm ot sure what) but after running the test everything came back normal. Dealer sent it back to Ford and Ford now told them to remove the heads and look at the valves to look for bent, burnt or otherwise damaged valves. I'm assuming that since they will have the heads off they can also inspect the pistons and cylinders.I'll let you know what they find out next.

 

a friend of mine had and 04 f150 5.4. took it to the dealer for the same problem,changed plugs and some other stuff(cant remember now what),but still had the problem after. after taking it back to the dealer a few times it was determined the dealer put in the wrong plugs,they replaced them with the propor ones and never had the problem since.

 

No one really knew what the issue with my truck is so I'll keep updating until I find out the fix so that if this ever happens to anyone else you'll have an idea. So my truck has now been in the shop (Ford Dealer) for 24 days today. In addition to my last post ford has replaced all the valve springs, taken the heads off and inspected all the valves to check for bent or burnt valves. All valves were good. They also inspected the cams and the phasers. All looked good. They are running test and taking pictures and sending them to ford who then reviews them all and tells the dealer what to do next. After inspecting the head and looking at the pictures ford told the dealership that the valve guides in the head were worn and that the heads needed to be replaced. They finally got all the parts in and got the truck put back together. TYook it out for a test drive and with the new heads as soon as the truck hits about 5K RPM's cylinder #4 just dropps out then #1 and #2 follow and the engine starts to rattle again like some one dropped a bag of marbles in the motor. So no fix. They are stumped and have no idea whats wrong so they sent everything back to ford and are waiting on what to do next. The service adviser thinks that at this point it might be the computer thats bad and doing something strange. I'm not sure if that covered under my extended warranty or not I'll have to check, but I'll keep everyone informed on what happens next.

 

First time posting, but have been reading a lot.

My do's the same thing as in the first part of your post,.

I've noticed It only happens when the torgue converter locks, when its in overdrive or if you have the overdrive off it will do it while in 3rd when the torgue converter locks? I also have done many thing trying to figure it out.( replaced all COPs, SparkPlugs, Fuel Filter, Mas air sensor, cleaned fuel injectors, cleaned throtle body, changed trans fluid)

Have they checked the Tansmission? Thats about the only thing left i can think of on mine and because it only happens when the torgue converter locks.

If you do find out let me know.

Thanks David

 

Yeah the transmission is brand new with less than 2K miles on it. I had issues with it first and they rebuilt it twice with no luck. So then they put a factory rebuild in it and it went out within 500 miles so they finally put a new one they found in it. So the transmission is good.

But to update everyone on the engine. After they put the new headers on it, it did the same thing. They have no clue whats going on and Ford is now sending an engineer to the dealer to look at it personally. With all the money they have spent on test and now this engineer to come in they could had put a new motor into it. And by the way it now has been at the dealership for 30 days today.

 

Thanks for the update and keep us updated. I will be taking by to the dealer for long to see if they can figure mine out too.

Thanks

 

Any update on the truck, did they find anything?

 

has anyone check the harmonic balancer (if it has one)? Could also look at U-joints, driveshaft trueness/balance.

 

Fuel pump?, fuel filter?

 

Probably not the u-joints. I thought I had a problem with mine but it wasn't. Was a combination of the LS being bad and a bad COP on No. 1

 

Here is another update. Since I've last posted they have replaced what they described as every mechanical part in the motor that they could and the truck is still jumping. So at this point they say they are not sure if it is even mechanical and that there may be an issue with the computer. The computer is not covered by my extended ford warranty, but due to having my vehicle for over a month the dealer ate the cost of it for me. Thank you, dealer. However, after putting in a new computer and a layover engine harness to bypass the old one just in case there was a short. Guess what? That's right, still doing it. Ford ESP has now authorized the dealer to put in a new motor, every part from the intake to the heads, wire harnesses and so on. They have now had my truck for 53 days and all the parts have not come in yet so I'm thinking another week at least. I'll let you know as soon as I know.

 

Wow, that is crazy. I wonder if they checked for plugged Cats?

 

Wow keep us updated