Flashing CEL/glowing cat

Just replace the gasket, probably fried it.

 

So is there a chance the cat is ok?

 

One way to find out is to remove it and see if it still has the honey comb on the inside, then if it does, shine a light through to see if it passes through the other side. If you have honey comb, and light passes through, it may have survived.

 

The reason your Cat is glowing is because it is burning massive amounts of unburned fuel. This is likely becaseu at least on of your engine cylinders has stopped working - Gas being put in but just dumped out and down to the CAT. It could be because of a bad plug, wire, or something that is casuing your cylinder not to fire

 

So is the fact that I have good pressure at the tailpipe a sign that the cat is not clogged? Just really trying to avoid cutting it out to check it.

 

Shouldn't have to cut anything, just when you go to replace the gasket, unbolt the cat from the vehicle and shine a flash light on one side and check for light on the other. The cat should be close enough to at least one of the flanges to see if the honey comb is intact. Then you can shine the light there or attach the light to a lanyard and snake it through from the other side. The only cutting that you may have to do is on rusty exhaust fasteners, just replace those with stainless. And when you bolt everything back together, it doesn't require a lot of torque, maybe 20 ftlbs at most.

 

Thanks! Yeah the bolts/nuts on the exhaust side of the cat are completely rusted together..the flange looks pretty bad too.

 

Also, is it safe to say the bad plug caused unburnt fuel to enter the cat, then causing it to 'overheat'..and not the other way around. In other words, could a bad cat cause the plug to foul/misfire?

 

Most likely it was the cylinder misfire that caused your problems, if it was the cat, you would've seen problems across all cylinders and the engine may have not stayed running

 

Great! Thanks much for your help!

 

Something else that came to mind. I noticed that my gas mileage has dropped off the past few months (by 30-40 miles per tank). Could this indicate another issue that caused the plug to go bad? Or can a fouling plug cause a decrease in gas mileage.

 

Fouled plug can cause that, plus many other factors. Also consider you are using winter blended gasoline as of about October which will get you less mpg

 

So..back to square one. After changing the plugs and it seemed to run fine yesterday. I didn't drive it but just let it idle and revved up to ~2500 rpm's and everything seemed smooth. Thought everything was good. So it sat overnight and the battery died (left key in ignition). The after jumping it and starting it is now idling terribly..intermittent shaking, squealing, and lack of power (just drove back and forward a little). The squeal does not start right away (takes a few seconds), then squeals non-stop. What could that be? a belt?

I did get the same code for cylinder 4 misfire (which I thought I cleared yesterday, but not positive). I cleared it again and started back up and could not get the code to come back on (but still idling like crap). So would the misfire code immediately if it is indeed misfiring?

Also, for what its worth..the old spark plug that was in cylinder 4 was black and sooty.