1997 Vortec 5.7 exhaust, shorties CEL

[Ozzy4194]

I have a 1997 Z71. Dual cats. Can anyone tell me for certain, if doing a cat back exhaust (dual mufflers into single 3" tail pipe) will trigger the CEL? And how about with shorty headers? thanks!

 

[Nad_Yvalhosert]

Well, let's think about this. Are there any sensors behind the split flange on a Vortec? Why yes there are. So, does your cat back system have a place to transfer B2 downstream O2 sensor?

Shorty headers are a decent upgrade over restrictive manifolds, but be aware of the need for proper EGR plumbing on the driver side. The tube is NLA.

 

[Ozzy4194]

I'll be adding an 02 bung on the after flange pipe that needs it. I'll be running the EGR. What I'm concerned about is PO131 and 151 lean codes.

 

[b454rat]

As long as both up stream sensors are there, then should be ok. Down stream ones only monitor the health of the cats, but can be removed. I did it to a couple trucks, put spark plug non-foulers in first then the sensors, no more check engine light.

 

[Ozzy4194]

OK thanks.