Hey guys,

I'm having a feeling that my front cat is plugged up. I have two cats, one is a 2 into 1 right after the 02 sensor, the other is just a 3" in/out converter. The 3" in/out converter (2nd one) has been replaced within the last year (it's a catco high-flow). The front cat is the original, 104k mi on the truck.

The last 6 months or so I've been having some engine difficulties, and has been running rich at times. I have a feeling that me driving it that way has plugged up the cat now. I drilled a hole in one of the y-pipe's tubes, and a hole after the 1st cat. Both of the holes seem to have even pressure if I put my hand infront of the exhaust coming out of the holes and have someone rev the engine a little.

Now I have the hole in only 1 of the y-pipes (can't have both together through 1 hole) so that means the hole infront of the cat is from only 4 cylinders...not all 8...but the pressure is still even...would that indicate it's clogged? The motor runs awful and has no power. Kinda sputters and does feel like the motor is having trouble pushing exhaust out. I wanted to take the cat out and put a 2 into 1 pipe in it's place for now...but I have to drive to NH tomorrow and on a 5 day trip to MD on monday night. I don't know if I can pull that off as it's not an easy thing to do.

So what exactly are the normal symptoms of a clogged cat? Thanks.

 

A clogged cat will rob a good amount of power, and sometimes smell funny. Also, check your oxygen sensors. They can go bad and cause your engine to run rich. A dirty MAF will also cause that.

 

My dads work van caught fire with a clogged cat.....not a raging inferno but very very hot with smoke. He said it started running very poor with no power for about a week.

 

Yes, a clogged cat will sometimes get cherry red, VERY, very hot. Testing with an intake manifold vacuum gage is the sure-fire way to tell if a cat is clogged.

As Ken says, a faulty or dirty MAF will give those (lack of power) symptoms you describe.

 

Well the MAF system is not currently in (it's running on it's stock speed density system). The MAF is a conversion kit, I have since removed.

I cut the cat out today and punched its contents out. It doesn't have any blackness inside the cat at all...was all grey honeycomb.

The interesting thing is that with it cut off and idling, it would make a small pop/poosh sound every couple seconds. You could feel the change in airflow on the pipe from the left bank, but not the right bank. I've gotta look into this more, but thanks guys.

 

Sounds like you have an ignition miss. Also, if the cat wasnt black inside, then you probably were not running as rich as you thought.

 

Yup...that wasn't what I wanted to see.