I don't know a whole lot about exhaust systems and whatnot, so I'm not sure if it's a muffler going bad or the catalytic converter going bad. Here's the deal...my 2001 monte carlo runs louder than it should... when it hits 3500-4000 rpm... the engine will sputter...and once a few weeks ago, the check engine light came on but then went out the next day before I could take it in to see what's going. I know GM has a special warranty extension on the catalytic converter, but the Chevy dealer wants $40 if it isn't the catalytic converter going bad for it to be looked at...what are your guys' thoughts?

 

Even if a light is not on, I believe a code should have been stored and if you go to any place that reads codes they should be able to bring it up.

 

Chibi is correct....even after the light goes off, it stores the code, but only stores it for a set number of key turns, I don't know how many exactly...but get it in ASAP.

Sounds to me like the CAT, not a muffler...

 

Yea the code will be in the systems memory but you can go to many auto parts stores and they will check it out for free. Does the exauset smell like roten eggs because that usually means a bat cat.

 

does the engine lag every time when u hit 3500-4000 rpms?

 

IF it is the cat and your falls under the Special Policy they can't charge you. Call GM direct, that's what I did and they set up the appointment but I already knew mine was the cat, it was throwing p0420 code. They told me if it wasn't the cat then I'd get charged for diagnostics. Mine was completely free.

 

I never knew I could have it checked after the light went out...I will have to do to that... when I come to think of it, it does smell horrible. And yes the engine does seem to lag at 3500-4000 rpms.

 

If you own a 3800 series engine read:

If it's the cat, AND they won't cover you and try to charge you like $700 laugh in their face and leave.

Then go to ZZPerformance.com and buy a ZZP Downpipe + High-Flow Cat for like $250, and have them install that

 

How long does the warranty cover them?

 

Yeahh.... 120,000 miles or 10 years on the 2001 Monte Carlo.