I have a 2004 F150 XLT with the 4.6l V8. A month ago problems began stacking up. At speeds above 40 the truck becomes very sluggish, almost jerky with a severe lack of power. So I began to check things off the list by replacing items I was able to do.
Replaced,
PCV Valve
Fuel Filter
Spark plugs
Transmission fluid & filter
Cleaned,
Throttle body
K&N Air filter
MAF sensor
Before changing the plugs I had a misfire code and so I replaced cylinder 3 COP. Finished up yestarday with a test drive. 0-40 very soft and smooth, but no power. Above 40 absolutey no power aand truck shutters and seems to be struggling overall. Please, can anyone help? Is it something simple or do I need to take it to a mechanic? Willing to try anything. Love my truck and life without it sucks! Again, please any help or advice is beyond needed and very appreciated!

 

What brand plugs and COP you use?
Take your truck to an exhaust shop and have your cats tested. Kinda sounds like they are plugged.

 

Sounds like a coil. I'd check the fuel pressure, just in case.

 

how's the truck under heavy throttle? Sounds a little like it could be a clogged cat. Last car I had could barely attain freeway speeds when the cat was shot.

 

I installed OEM, motorcraft platinum spark plugs. Had Autolite plugs in it. As for type of coil packs, unsure. New one was purchased at O'Reilly's. Others are yellow, sorry all I know about them.
How would I check the fuel pressure? Also with no codes or check engine light on, how am I do know for sure if it is the Cat?
Is there anyway to test COPs to maye find a bad one? Would a bad CAT not give a code or could it go bad without a code or check engine light? Also what would be the best replacement CAT? I am looking at Magnaflow. I am a disabled vet who has limited funds, however I only want the best, but without breaking the bank, ya know.

 

Like I said before take to exhaust shop they can read all the sensor and see if the cats are plugged. Yes magnaflow high flow cats are all you need they are the best. You only need 2 to replace all 4.

Also I would suggest getting rid of those aftermarket cops. They have been known to be junk. Replace with motorcraft, Visteon, or araparts cops

For checking the fuel pressure you can read it the your obd2 port. It's all electronic.

 

common issue with accel garbage cops...


start by removing those and installing some stockers, since you're on a budget go to your local wrecking yard and get some used ones

 

You've checked the FPDM?

https://www.f150online.com/forums/ar...placement.html

 

So I looked under the truck and my new questions are how to get the passenger side exhuast out? I also am unble to see where the first bank on the same side, gets unplugged. I am having trouble getting the 2 O2 sensors out of the driver's which I was able to get off and the section from the mounting spot to the headers to about 3 inches past the second converter. Then my last dilemma is going to be how am I to put the O2 sensors back in after i get the new Magnaflow, high flow cat in place. Iam no mechanic but if I can do the job then i am willing to try anything I can . And will anything get damaged if the truck is started with no exhast?

 

I did not check the fuel pump driver module. I can't get my spare down and i don't see how i can cut it off. Once i get my exhast put back together then if you have any suggestion on how i can get my spare down and out of the way then i want to check the module .

 

That was a little confusing so I'll try to answer what I understood.
If you order the magnaflow cats with O2 sensor bung in them, then you can just thread the new O2 into the Maggy's.