Power issue 03 5.4

[Fanatic1074]

I tried posting this a few months back and no 1 has any ideas so I am going to try again. I have a 2003 ford expedition XLT 5.4. Over the course of the last year I have been experiencing some power issues. I noticed the power issue the most when I am pulling a load. It's hard to properly explain but basically it just feels like it has no power at all. It does not throw any codes either. It also does not do it 100 percent of the time. I have tested the oxygen sensors with a OBD reader. All of the sensors read between .1v and. 9v. Now I know that does not always mean they are food but I don't wanna replace something without good reason. Any ideas?

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[smith]

I had a bad COP (coil) and it would only act up sometimes and would not throw a code. Finally after 6 months started acting up more often and did throw a code. That was the only way I found it.

 

[rburch]

I dont have the 5.4 so im no expert, but one thing that i have learned on here by sitting back and reading posts is that the COP on the 5.4 is the cause of allot of problems.

Look at the top of the COP. There is some kind of epoxy or something like that that seals the internal components, if there are any cracks then the COP needs to be replaced. Also the boots on the COP age and get brittle from the heat and that can cause the spark to not get to the plug.

You should also clean the MASS with some Mass Airflow Cleaner, might help also.

 

[Fanatic1074]

COP is another name for coil packs? I will check them out tonight. I have actually already clean a mass air flow sensor. My only question about the coil pack is if they were the cause of the problem when the truck does act up wouldnt the engine shake?

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[rburch]

Correct but there is a coil for every plug. And you wouldnt necessarily get any shaking.

 

[starbuck478]

I agree with checking the COP's I've gotten that feeling before too when two of mine went bad where you can tell you're not getting the power you should be. Another worth while general maintenance thing to do while your in there is check the plugs themselves when I had to dig through mine I found alot of them had gotten gummed up especially the further back ones

 

[Fanatic1074]

Ok bought all new coils for the truck. 8 pack of Accel's. I have heard good things about these so i pulled the trigger. The only problem is, it did not fix my issue. So i am back to square one. Tested the MAF and its all good as well. Plugs were all changed out about 10k miles ago, hard to belive they would be bad already considering the stock ones looked pretty good for a truck with 100k on it. I did notice that when the Alternator kicks in the RPMs drop about 50-100 Rs and the exhaust tone changes. I dont remember it doing that. Starting to wonder if the Alternator is causing drag. However the amount of power i loose when this happens is dramatic. i would think the belt would slip and squeek before i would loose that much power. What do u guys think?

 

[2000eb]

alternator would not be kicking on and off that would be your ac compressor and you will loose a little bit of power. make sure ac is off heat off etc pull a load and see if anything changes. the ac compressor has a clutch and thats the sound you hear and yes when it kicks on vehicle will automatically adjust rpms causeing exhaust tone to of course change

 

[Butch Smith]

I would replaced the fuel filter. I replaced mine and I noticed more power and a smoother ride.

 

[Fanatic1074]

alternator would not be kicking on and off that would be your ac compressor and you will loose a little bit of power. make sure ac is off heat off etc pull a load and see if anything changes. the ac compressor has a clutch and thats the sound you hear and yes when it kicks on vehicle will automatically adjust rpms causeing exhaust tone to of course change

I understand why you would say that but i have verfied that it is the Alternator. I sat in front of the truck with it on and hood up. Its definantly the alternator kicking on and off causing the exhaust tone change. It will even do it with the heat/ac off.

Ohh and Butch smith, the Fuel fitler was changed about 1000-1500 miles ago. even the old one was pretty clean.

 

[TN_XLT]

A friend of mine warned me about the fuel filter. Here's the kicker: there are two filters; one towards the engine and one towards the fuel tank. The one causing him issue was the one towards the tank. His exact advice was: "when your expy starts loosing power, don't panic, just replace the rear fuel filter."

Edit: I'm not sure his was an 03, so this may not be the case for yours.

 

[Fanatic1074]

A friend of mine warned me about the fuel filter. Here's the kicker: there are two filters; one towards the engine and one towards the fuel tank. The one causing him issue was the one towards the tank. His exact advice was: "when your expy starts loosing power, don't panic, just replace the rear fuel filter."

Edit: I'm not sure his was an 03, so this may not be the case for yours.

Where is the filter near the motor? i changed the one under the drivers side doors.

Ok got some news and maybe someone can advise me here. I took thermal readings before and after both cat's. My infared thermometer only goes upto 400. It maxes on both sides before the cats. After the cats on the driver side its around 300, passanger side is about 350. I thought that it was suppose to be higher on the exit then the entrance, right? i also thought it was only suppose to be around 250.

Can anyone shed some light here?

 

[ChrisUK]

I'm interested in this too, as my 2003 5.4 has been down on power for a while, and it's using a lot of fuel - I'm lucky if I can get over 10.0 mpg driving sensible.

I've replaced the fuel filter (near tank, don't know of one near engine?) new air filter, new oil and oli filter, cleaned the Mass air flow sensor - was still the same, so I just put 8 new spark plugs and 8 new coils on - I was hoping this would help, as although the truck has only done 65,000 miles, the plugs looked quite bad - Although it seemed to improve the power a bit, it's still not how it used to be, and driving in 2 wheel drive, not going over 70mph, steady accelerating, it gets about 12.0mpg

I've now replaced the vacum pipes and the PCV elbow - and still the same!

The truck runs smooth and quiet, on idle its so smooth you can hardly tell its running, and revs nice and smooth - just not as much power as it used to have, and uses waaaaaaay too much fuel! (when I haul my travel trailer, I only get 7mpg!) oh and no engine or service light on either?

Anyone got any ideas???

 

[Fanatic1074]

I will be taking my cats to get tested soon, ill let you know what i find out.

 

[Fanatic1074]

OK, update.

I bought a back pressure tester and tested the back pressure and i do not have plugged cats. I also went ahead and replaced o2 sensors and still have the same issue.... So tired of this. I am actually at a garage right now getting the fuel pressure tested.

I welcome any other ideas.

 

[Fanatic1074]

Ok, fuel pressure is fine.

53-59 PSI at all times. I was even able to replicate the problem during the test. However the tech was not in the truck while i did it. Im out of ideas.

 

[Fanatic1074]

Ok something i noticed today.

When driving the truck occasionally ill be slowing to a light or sitting at a light and ill hear the engine drop to a deeper tone and the RPMs will drop abou 100 RPM. Does not seem to be connected with the alternator or compressor kicking on either.

 

[Fanatic1074]

Going to post on my progress and hopefully someone can help.

I have now replaced the Knock Sensor, ECM, PCV Valve and PCV Valve Solenoid.

Still the exact same issue.

Im open to any ideas.

 

[Whack]

Is it always under load?

Is it always repeatable? (same hill, same load, same rpm, throttle position?)

How new are the spark plugs? Have you pulled them as part of this?

 

[tsgrpr97]

Are you able to check spark retard with your scanner?