I posted here about the problems my '99 camaro 3.8 is having well today I got the plugs and wires done the misfiring is gone but it's still stumbling under idle. It also had a loss of power as well. The mechanic said my coil packs were fine,but we scanned it again and got codes for a bad EGR valve and cat converter he says my cat converter is going bad.

The car has a new fuel pump,sending unit and alternator and battery. I had the alternator checked and the mechanic said it was putting out to much voltage but two different autozone stores said both the battery and alternator were good and putting out the proper voltage.

I'm at a loss here I've taken this car to three different places and two of then said my cat was going bad,the car has 184,000 miles so I think it's possible the cat may have had it.

Will with a bad cat converter or bad EGR valve leave me stranded? And will replacing both cure my problems?

 

A bad cat can cause significant power loss. The cat has two "beds" which are pieces of ceramic honeycomb coated with minute amounts of precious metals. Each bed is maybe 2 inches thick and has lots of tiny parallel passages that the exhaust flows through. Each passage is too small to push a pin head through.

If you have a misfire condition that causes a lot of unburned fuel to leave the engine the converter, which operates at 600+ degrees F, burns them up. It's too much for the cat to handle, though, so it overheats (like to 1800F) and the ceramic matrix melts. All those tiny passages plug up, effectively constipating the engine.

Most of the time the blockage is just partial so the engine starts and runs but lacks power. Early 80s cadillacs had a big problem with melted cats and some wouldn't start again after you shut them down.

A bad EGR valve can cause the injection system to overfuel, again causing cat meltdown.

Sometimes the ceramic matrix breaks into pieces and moves rearward and rotates. Then it blocks the cat outlet and that will shut the engine off. A rattling noise from under the car is a sure sign that the cat innards have broken up and are moving around in there.

Here are a couple of cat pics:

 

If you know the cat is bad, take care of only that first. If it's restricted, it could cause exhaust pressure to back-feed to the EGR, giving a false error.

 

Thanks for the replies so far last night the car dies on me and won't restart had to cranks it a few times it started but stalled again and I could smell fuel vapors like its flooded or something. I know the battery isn't dead cause I have power it's like it's not getting fuel. The funny thing is it's got a new fuel pump and when I gave it gas after starting it it didnt stall out,I put the pedel to the floor but the car wouldn't move when I had it in drive. Could this be a fuel pressure regulator issue?

It's like the car is crazy or something it's driving me nuts were is the Fuel pressure regulator located on this thing?

 

a plugged cat can cause all the things you are experiencing. get it or them changed depending on if you have one or two.

 

Yeah, the stuff you posted most recently reinforces the bad cat theory. To test it just loosen the bolts/nuts that secure the exhaust headpipe to the manifolds. Chances are that the engine will start and run.

 

So im having the same problem only difference is my camaro is strait piped no cat can anyone help me

 

Do you have the same PCM codes?