Running Rich
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 22
Likes: 1
Running Rich
I know that it is not the responceable thing to do, but I had to replace the exhaust system on my 86. I chose to go without a cat and installed a true dual system. My question is this, from the smell of the exhaust I think the engine is running rich. I there something else I should do to tune for the new exhaust system. Thanks in advance for any help you all can provide.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Running w/o CATs is going to change the smell anyway. You sure it's not just the "unconverted" exhaust you're smelling? Is the MPG worse? Do you see black smoke (puffs)? Is there heavy black soot in your new pipes? Have you tried unplugging the battery -- to get it to "relearn" fuel trims faster?
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
IMO you need to drive it with a scanner to besure its going into closed loop and active. Fuel trends can also be monitored. Sometimes O2 won't heat up once the back pressure goes away. Heated O2 canbe wire in.
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
A scanner reading live data from the ECM through the OBD port will tell you whether the engine is dropping into closed loop. Sometimes larger exhaust systems or moving the O2 downstream will have this issue, the O2 needs to be in a similar location with the new exhaust, and even then, headers can cause it to go back to Open loop operation at idle. If that is the case, you'll need to install a heated O2 sensor.
But running catless you'll smell fuel either way.
But running catless you'll smell fuel either way.
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