A friend has a 01(5.4) started doing same way. Long story many trips to ford, the back 2 coilpacks were getting wet seal around hood leaking when rain/wash on driver side this after $80 a pop coilpacks replaced

 

If your cat is stopped up you would see a code for all the cylinders on that bank. Think about it. Why would one cylinder lose power and the other three not.

 

ya , im not getting anyother codes after switchn the coils around, still runs like crap, ill have to wait and see if it will toss another code.

 

You can find someone with a scanner and look at the mode 6 data in the pcm to find out what cylinder is losing power.

 

hey bubba----- truck has great power, under aload no power, smells lean exhaust, i can rev her up... put put her in gear she shutters all gears. thats when i hold the brake in im sure she will do the same on the road. like i said ihad the code for misfire in 3---- and i switched 1 to 3 runs the same no code yet.... almost seems like a tranny issue any ideas?

 

What year is your truck?

 

its a 2001 ssuper crew..5.4

 

you could have plugged up cats.

a cheap way to test them without cutting them off:

https://www.f150forum.com/f6/trouble...x2/#post730754

also if your cats are bad there is a reason. try compression check if your ignition checks out like it sounds it has.

a quick way to check for a missfiring cylinder is to point a infared thermometer on the exhaust manifold coming right out of the head on each cylinder. Keep in mind as you check back toward the firewall the temp will get hotter because the exhaust from up stream helps heat it. Look for something 100 degrees or more off.

 

also sounds like you have independent coil packs. If you get a miss switch the coil to a cylinder you know to have not missfired

 

A misfire can do damage to your cat. I would fix the miss immediately. Coil failure is common-I have probably replaced a hundred of them in past few years. I would remove the plug, clean it, check the porcelain part for hairline cracks and replace it along with the coil.
Removing the o2 sensor in front of cat will relieve some pressure and may help you determine if it;s plugged. This is also a good place to measure pressure. You can adapt a pressure guage to fit the hole. Compare the reading with the reading on the other bank.
When a misfire occurs, the unburned fuel gets absorbed and oxidized by the cat. This uses so much oxygen in the cat that it reduces its efficiency-hence the cat code.
hope this helps
good luck