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.