Car all of a sudden sounds like a race car

[chopperman]

So Im driving down the belt parkway, my motor is misfiring so im only at 60 and Im trying to stay on the throttle as much as I can because if i slow down it will take forever to get to speed again. ANYWAY the misfiring went away and I was now at around 70mph and was cruising around happily. All of a sudden I hear a really deep sound. I decided to get to my desination instead of pulling over. When I get there my car sounds like I ******* put a exhaust system on it. Its nice and deep. I love the sound but I what to know what is wrong with it. I must say that my check engine light was on and when I checked it 2 weeks ago it said that my precat was messed up. I had an appoitment with the dealership to replace it because I heard it was under warranty when the car is under 80k miles but I wasnt able to go. Now Im gonna make another one. Can anyone tell me what is wrong or happened. It just all of a sudden started making this deep noise. I still have exhaust coming the tail pipe. Can it be that it has a hole in it? Thanks

 

[Kansei]

That's a really, really bad misfire. Happened to me when both of my aftermarket plug wires went bad.

Was your CEL ever flashing?

 

[JOMO]

also could be that your gasket in the precat is bad, causing a exhaust leak.

 

[chopperman]

Yes my cel was flashing because it was also misfired a little last night. Is that gasket covered under warranty

 

[JOMO]

Yes my cel was flashing because it was also misfired a little last night. Is that gasket covered under warranty

Should be, but it does sound like a misfire though. Check your plugs if you can.

 

[Spitfire70]

Sounds like an exhaust leak to me.

 

[TheMAN]

you killed the cat because you drove around with the flashing "CEL" when it was telling you NOT to drive it

now that you broke other s*** in your car due to your neglegence, you may have to pay for those broken parts

 

[Kansei]

Don't assume it's negligence Edwin. I had to drive my car for a few miles with the CEL flashing (it only flashed under heavy throttle though, so I avoided as much as possible) because it was an emergency and I HAD to get where I was going. Luckily I don't have a pre-cat and it didn't wreck my high flow cat. But yeah, I also am completely ok with paying for broken parts.. nothing on this car has ever broken that I didn't cause.

I'm fairly certain the owner's manual does say to definitely never drive the car with a flashing CEL... people should sit down and read through the manual the first day they get the car, hell I even did that the first day with my G5 rental car

 

[chopperman]

car has brand new stock plugs that I put in about 2 months ago.

 

[Kansei]

car has brand new stock plugs that I put in about 2 months ago.

what about the plug wires? both of my (admittedly aftermarket crap... sparkco (rant)) plug wires were kinda bad and then got wet and caused all sorts of misfiring.

 

[chopperman]

no i didnt change the wires, Ill try that. But is the noise from my cat? Cuz i sounds like it is coming from the middle of the car and not the rear. I am assuming it is the gasket.

 

[Kansei]

Well if the noise is happening when the CEL is flashing, that's the sound of catastrophic misfiring and yes it is a wild sounding thing. How many miles are on your stock wires?

 

[chopperman]

I dont think they were ever changed car has 78k. I dont think it is misfiring, I still have all my power and it doesnt have slow acceleration or any symtoms of misifiring. When my motor was misifing the cel stays flashing for a couple of days until it will stop. So I doubt it could ne catastrofic misfiring.

 

[Kansei]

All your power still? well that's interesting! I'm starting to think maybe your cat is plugged from when you drove it while misfiring.

 

[P-Funk!]

^x2. And then a seam opened up relieving the back pressure. Inspect the exhaust system carefully.