Need catalytic converter advice
Thread Starter
Advanced
Joined: Jan 2008
Posts: 50
Likes: 2
From: Tavares Florida
Need catalytic converter advice
I recently bought My first C5.
Driving back from Arizona we averaged about 25 MPG. In New Mexico the roads demanded Me to drive fast. Hammering it down it smelled bad -rotten egg smell- This has always been an indication to me of a converter getting clogged. 2500 miles later My mileage is at 20MPG. No check engine or other. Mileage is 72,000. Car runs well
1) does the smell indicate a problem?
2) any input on maintenance I should do
3) if cats need replacing any suggestions on purchasing?
Thanks in advance, Dave
Driving back from Arizona we averaged about 25 MPG. In New Mexico the roads demanded Me to drive fast. Hammering it down it smelled bad -rotten egg smell- This has always been an indication to me of a converter getting clogged. 2500 miles later My mileage is at 20MPG. No check engine or other. Mileage is 72,000. Car runs well1) does the smell indicate a problem?
2) any input on maintenance I should do
3) if cats need replacing any suggestions on purchasing?
Thanks in advance, Dave
Pro
Joined: Dec 2003
Posts: 651
Likes: 1
From: Z16 #1990 Ridgecrest CA
Hey Dave,
Is your Vette completely stock? (stock cam/tune/exhaust/catalytics etc)....If so, I'd consider new front o2 sensors. Also, run some good quality fuel injector cleaner though the tank too. I use seafoam in my gas tank every 5k. If it turns out that the stock cats are bad, a nice set of headers with "high flows" should take care of it
Good luck
Is your Vette completely stock? (stock cam/tune/exhaust/catalytics etc)....If so, I'd consider new front o2 sensors. Also, run some good quality fuel injector cleaner though the tank too. I use seafoam in my gas tank every 5k. If it turns out that the stock cats are bad, a nice set of headers with "high flows" should take care of it
Good luck
I recently bought My first C5. Driving back from Arizona we averaged about 25 MPG. In New Mexico the roads demanded Me to drive fast. Hammering it down it smelled bad -rotten egg smell- This has always been an indication to me of a converter getting clogged. 2500 miles later My mileage is at 20MPG. No check engine or other. Mileage is 72,000. Car runs well
1) does the smell indicate a problem?
2) any input on maintenance I should do
3) if cats need replacing any suggestions on purchasing?
Thanks in advance, Dave
Driving back from Arizona we averaged about 25 MPG. In New Mexico the roads demanded Me to drive fast. Hammering it down it smelled bad -rotten egg smell- This has always been an indication to me of a converter getting clogged. 2500 miles later My mileage is at 20MPG. No check engine or other. Mileage is 72,000. Car runs well1) does the smell indicate a problem?
2) any input on maintenance I should do
3) if cats need replacing any suggestions on purchasing?
Thanks in advance, Dave
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
First thing is to check for codes from the DIC. See if it points at anything. From the photo in your SIG it looks like you have other then stock exhaust system and maybe prior owner removed the cats, causing the smell. I agree with getting some fuel cleaner put through it, I use Techron that is Ok'd by GM to use. What grade fuel are you using? Low octane will cause spark retard which will reduce mileage without setting any codes.
Drifting
Joined: Jan 2008
Posts: 1,722
Likes: 138
From: Florida
St. Jude Donor '09
Team Owner
Joined: May 2005
Posts: 23,682
Likes: 9
From: Flagstaff Az.
Easiest way to be sure is to take the car to a muff man you can trust. They will drill a small hole in exhaust system just a head of each cat. They will insert a psi gauge and the reading will tell if the cat is plugged. They simply weld the hole up. 
Thread Starter
Advanced
Joined: Jan 2008
Posts: 50
Likes: 2
From: Tavares Florida
Thanks
My last couple of fill ups were of no name brands of gas. I picked up some cleaner and will fill up with premium Shell or BP. Link to converters also mentioned replacing o2 sensors. So they are ordered. I will post results. Thanks Dave
Race Director
Joined: Oct 2008
Posts: 11,482
Likes: 0
From: Common courtesy and common sense are not common.
St. Jude Donor '09-'10-'11-'12-'13
The cat will be very clean with the heat gererated by a track day.
Drifting
Joined: Jan 2008
Posts: 1,722
Likes: 138
From: Florida
St. Jude Donor '09
My last couple of fill ups were of no name brands of gas. I picked up some cleaner and will fill up with premium Shell or BP. Link to converters also mentioned replacing o2 sensors. So they are ordered. I will post results. Thanks Dave
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski