I want to remove the O2 sensor and temporarily hook up a pressure gauge and check back pressure. How much is too much? My truck has 150K on it and I think the cats are getting clogged.

John

 

I would say if you are thinking they are getting clogged, replace them. Your truck will run horrible without the O2

 

2 to 3 pounds is normal 4 or high mean it's most likely clogged.Yea drill a hole then weld it up when you're if you can, your truck will run like crap without the O2 sensor.

 

Will running it for 5 minutes without the O2 to check backpressure hurt anything other than make it run like crap? I just want to check the pressure, not drive it w/o the O2

 

So, it's 2 or 3 pounds at idle? What will it be at a constant rev, say 1800 RPM. I don't have this problem but I have always wanted to know.

 

That won't hurt a thing, and it will run just fine for the 5 minutes it takes to test the pressure.

 

A better way to do it is to drill two holes small holes in the exhaust pipes on either side of the cat. With the engine idling put your hand over each hole and see if you can tell a difference in pressure, it should be fairly even, if it's pushing harder in the front hole (towards engine) it's clogged.

An aftermarket high-flow cat is about 60 bucks from summit racing.

This also belongs in the exhaust forum, moved