How do you if the cat is backed up?

 

May idle OK but will have very low power and won't rev up under load.

 

Sounds about right... Any way I can confirm it's the cat??

 

the engine will also sound wayy different and basically you can floor it but it wont really go anywhere.. you could try unbolting the exhaust fromt he flange behind the cat and see if it gets better. a vacuume gage readng from the intake is your best bet.. find a vacuume port between the throttle body and the intake valves and hook upi your vacuume gage. it should rear at least 13Hg's at idle and under load should get closer to 0 if it goes positive you efianyl have a clogged exhaust

JOSH

 

my truck felt like it was gonna stall when i had that problem. you'd lose a lot of power and idle might be all over the place...at least mine was.

 

use one of thoughs tools that mesure surface tempature. check the cat then cheak the pipe before it.. if the cat is cool and the pipe before the cat is hot then its a cloged cat. the cat should be hotter then your exhuast pipe.

 

your check engine light should come on. It's it does end up being the cat, take it to Ford. 80,000 mile warranty on emissions.

 

It won't always throw a CEL. Usually as cats get clogged it's a slow process that takes years.

Some indicators..
Exhaust note is quieter
Exhaust leak upstream of the cats
Low power
Auto tranny will not seem to be shifting right. (delayed shifts)
Low vacuum readings
Runs worse when you've put some heat into them. (driving for an hour out on the hwy)

Rich