Rough Idle after Header Installation! Help!
Melting Slicks
Joined: Feb 2004
Posts: 3,131
Likes: 148
From: Sugar Land TX
This has been done and when people had them reversed it fixed the problem. Why it matters is that info used for each bank is specific to that bank. A rear 02 sending back info on the wrong bank makes it not adjust when the PCM commands a fueling event. If the O2 says its too hot on that side and the PCM commands more fuel to cool the cat with no response, it commands more fuel. As its doing this the O2 on the wrong side isnt going to get any response for that side since its not reading that side.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Another fix would be to delete all rear O2 codes and turn off cat over temp protection but thats hack tuning to cover a header install error or a bad tune. I can respect the latter if you dont want to mount rear O2's or buy the wire extensions.
Melting Slicks
Joined: Feb 2004
Posts: 3,131
Likes: 148
From: Sugar Land TX
I tried deleting rear 02s to no avail. OL at the time was the only way I could get the car to idle decently. I thought I had the 02s on their respective banks but will never know for sure. Sold the car.
Thread Starter
Racer
Joined: Jan 2009
Posts: 286
Likes: 0
From: Madison MS
This has been done and when people had them reversed it fixed the problem. Each O2 is specific to that side and they adjust independently of each other. Why would you think a left bank O2 would be ok in the right side???
Why it matters is that info used for each bank is specific to that bank. A rear 02 sending back info on the wrong bank makes it not adjust when the PCM commands a fueling event. If the O2 says its too hot on that side and the PCM commands more fuel to cool the cat with no response, it then commands more fuel. As its doing this the O2 on the wrong side isnt going to get any response for that side since its not reading that side.
There are countless people running headers in closed loop without issue. Closed loop is the way it supposed to run and open loop only is for people who have it hooked up wrong.
Your symptoms are exactly what happens when you have the O2's reversed. You dont use band-aid fixes such as running in open loop. You fix whats wrong so it works properly. Take the O2's out and reverse the pipes they are in. Common symptoms will show ok perofrmance for WOT since its not closed loop. Its got messed up fueling though because it uses a long term fuel trend to act as a base for PE mode.
You dont need a picture; reverse the O2's. Since you say the car sounds great and runs great you are definitly not running on 7 cylinders.
Why it matters is that info used for each bank is specific to that bank. A rear 02 sending back info on the wrong bank makes it not adjust when the PCM commands a fueling event. If the O2 says its too hot on that side and the PCM commands more fuel to cool the cat with no response, it then commands more fuel. As its doing this the O2 on the wrong side isnt going to get any response for that side since its not reading that side.
There are countless people running headers in closed loop without issue. Closed loop is the way it supposed to run and open loop only is for people who have it hooked up wrong.
Your symptoms are exactly what happens when you have the O2's reversed. You dont use band-aid fixes such as running in open loop. You fix whats wrong so it works properly. Take the O2's out and reverse the pipes they are in. Common symptoms will show ok perofrmance for WOT since its not closed loop. Its got messed up fueling though because it uses a long term fuel trend to act as a base for PE mode.
You dont need a picture; reverse the O2's. Since you say the car sounds great and runs great you are definitly not running on 7 cylinders.
Thank you for explaining. I am new to the tech stuff so thats why I was asking for you to explain. I was not disagreeing. Its at the tuner as im typing this and he said he will fix the issue. He said the exact same thing you just said so hopefully when I pick up the car tonight it runs perfectly.
Thanks again
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
Can you (or have your tuner) log misfires and see if it is traceable to a cylinder or at least a side.
I had two problems after my install. One was a pinched O2 sensor wire. It eventually threw a code which made it easy to trace down. The second was a plug wire came loose after a few miles so it was firing only sporadically.
I had two problems after my install. One was a pinched O2 sensor wire. It eventually threw a code which made it easy to trace down. The second was a plug wire came loose after a few miles so it was firing only sporadically.
Thread Starter
Racer
Joined: Jan 2009
Posts: 286
Likes: 0
From: Madison MS
Well, I DID NOT reverse the rear oxygen sensors. My tuner turned them off in the tune. My car was just idling very low at 500rpm. After the tune it is now idling at 650 and no issues at all. Car went from 373 RWHP & 374 TQ to 401RWHP & 400TQ. Not a bad gain. 2008 LS3 A6
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
