2016 C7 Z06 No Boost
Safety Car
Joined: Mar 2004
Posts: 4,048
Likes: 1,478
From: South Florida
I'll check them out, thanks for the info. I had thought that the order was secondary cats and then secondary 02 sensors, I was under my c5 this morning and thats how it's laid out. If it's changed for newer cars, great information, happy to learn about it. I'll check the primary cats, see if they're clogged up or something. If they are, would that cause a 300hp difference? The car feels slow as hell, and I don't know if clogged cats would create that large of a difference. Thanks for the responses.
Clogged cats would cause a HUGE power loss yes. It can also cause red glowing exhaust pipes if you look under the hood and down the side of the manifold. Think about it, clogged cats means the engine cant get airflow through the engine. Airflow through the engine is power. Clogged cats would make the car feel like its down 300-400 HP easily. KEep pushing it like that and it will break something. The pressure inside the engine is going way up, and the knock sensors would be pulling a ton of timing. It would learn to pull timing way down in an attempt to save itself from blowing up. You could even get torque management timing coming in to pull timing down under throttle.
Thread Starter
Instructor
Joined: Jul 2022
Posts: 154
Likes: 24
The C5 never had 4 cats. It's primary cats were in the X pipe and the rear O2's were behind them. No Corvette had 4 cats until 2012.
Clogged cats would cause a HUGE power loss yes. It can also cause red glowing exhaust pipes if you look under the hood and down the side of the manifold. Think about it, clogged cats means the engine cant get airflow through the engine. Airflow through the engine is power. Clogged cats would make the car feel like its down 300-400 HP easily. KEep pushing it like that and it will break something. The pressure inside the engine is going way up, and the knock sensors would be pulling a ton of timing. It would learn to pull timing way down in an attempt to save itself from blowing up. You could even get torque management timing coming in to pull timing down under throttle.
Clogged cats would cause a HUGE power loss yes. It can also cause red glowing exhaust pipes if you look under the hood and down the side of the manifold. Think about it, clogged cats means the engine cant get airflow through the engine. Airflow through the engine is power. Clogged cats would make the car feel like its down 300-400 HP easily. KEep pushing it like that and it will break something. The pressure inside the engine is going way up, and the knock sensors would be pulling a ton of timing. It would learn to pull timing way down in an attempt to save itself from blowing up. You could even get torque management timing coming in to pull timing down under throttle.
Safety Car
Joined: Mar 2004
Posts: 4,048
Likes: 1,478
From: South Florida
Anyhow, yes to check the cats you would need to remove them from the manifold and the mid pipe. You need to be able to see both sides. You can also check for glowing manifolds or the cats themself once the car is hot. Clogged cats usually cause glowing red exhaust piping in front of them. It might need to be night time to see it though. Just a thought. If it doesn't glow that doesn't mean they aren't clogged.
Might be worth throwing on headers and tuning the car if your cats are indeed the issue.
Thread Starter
Instructor
Joined: Jul 2022
Posts: 154
Likes: 24
I literally just came back here to post a correction to what I said earlier. I was at the gym and thought, awww crap I forgot about the pup cats. Yes the C5's had pup cats and the rear cats were the main cats and were monitored, you are correct here. They switched this up in I think 2012 in the C6. 2011 C6's actually only had Primary cats but then the EPA rules had them back in 2012 through today.
Anyhow, yes to check the cats you would need to remove them from the manifold and the mid pipe. You need to be able to see both sides. You can also check for glowing manifolds or the cats themself once the car is hot. Clogged cats usually cause glowing red exhaust piping in front of them. It might need to be night time to see it though. Just a thought. If it doesn't glow that doesn't mean they aren't clogged.
Might be worth throwing on headers and tuning the car if your cats are indeed the issue.
Anyhow, yes to check the cats you would need to remove them from the manifold and the mid pipe. You need to be able to see both sides. You can also check for glowing manifolds or the cats themself once the car is hot. Clogged cats usually cause glowing red exhaust piping in front of them. It might need to be night time to see it though. Just a thought. If it doesn't glow that doesn't mean they aren't clogged.
Might be worth throwing on headers and tuning the car if your cats are indeed the issue.
Thread Starter
Instructor
Joined: Jul 2022
Posts: 154
Likes: 24
Yeah figured it out. A8 trans code was pulling ALL THE TIMING so it wouldnt get into boost at all. It was the internal trans harness in the trans itself. Horrible issue to have. The actual code was I believe a trans temp circuit high or something like that.
Heel & Toe
Joined: Jan 2017
Posts: 16
Likes: 2
From: Utah
Thanks for the reply! Goodness that sounds rough. I unfortunately am not throwing any codes so the search continues for me haha.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
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
Thread Starter
Instructor
Joined: Jul 2022
Posts: 154
Likes: 24