How do you check for clogged catalytic converter?
 

I am suspecting my car has low power due to a clogged converter. I would like to know how to check for that and what values I should be looking for when I test it? Also, is there a way to clean it?
Thanks,
Meza

The easiest way is the old fashioned vacuum gauge method. With vacuum gauge attached, rev the engine to high RPM while watching the gauge. A clogged exhaust system will show the vacuum go way up then fall back very low in just a few seconds.

Good luck,

This is incorrect. What LB descibes above is NORMAL vacuum gauge action for a well balanced engine

ASE A8, Engine Performance manual, page 60, reference states:

"To check for a restriction in the exhaust, attach a vacuum gauge to the intake manifold and run the engine at approx. 2000RPM, observe the vacuum gauge as the engine is allowed to quickly decelerate.

If the exhaust is FREE of restriction, the vacuum gauge reading will increase immediately upon closing of the throttle, then settle down to a normal reading. If there IS a restriction, the needle of the gauge WILL NOT show an increase."

This is logical if one sees the engine as a air pump that happens to have gasoline pouring into it, the action of the pistons creates a movement of air at the intake ( vacuum) and pushes it out of the exhaust ( pressure) if the exhaust is plugged or restricted, then the vacuum will not increase.

Another way to check for same is to attach a pressure gauge at the after cat O2 sensor port ( if so equipt), a normal reading will be around 2psi at idle and 3 psi at 2K RPM.

I'd just uncork it at the exhaust manifolds (loosen up the exhaust system and drive it). This is just to test it though. Don't do it at 3am (or before 8am on Sunday) and leave a couple windows rolled down. Just a short drive to see if it makes a difference.

Gilly