Oldblue

Yes sir, the Bosch units don’t seem to satisfy the ECM’s parameters

SheckyB

Would This end of Muffler Cause PO171 Code?

donbrew

That is the resonator. Since it is after the #1 O2 sensor it should have no bearing on it. It is basically a straight through pipe.

SheckyB

And at The Far End On tail ... ( muffler) ? That Would Not Restrict either?

donbrew

The #1 O2 sensor is the one closest to the engine. It's job is to control the A/F ratio by sensing what gasses are passing by it. Constriction should not affect that unless it caused a backflow, but that would cause some odd stuff to go on passing the catalyst twice.

Anything affecting the A/F takes place between the MAF, where the amount of air is measured going in, and the #1 O2 sensor that measures the O2 left after it is burned.

Usually caused by a vacuum leak. This includes :
a hole in the vapor return pipe
a cracked EVAP canister
a malfunctioning EVAP purge valve, or any of it's tubing
a cracked intake manifold
a cracked/leaking/missing PCV hose
a crack in the elephant trunk between the air cleaner and the throttle body
a cracked flex pipe
a bad exhaust manifold/gasket
low fuel pressure

Probably more but I'm getting cramps in my fingers

Oldblue

The flex pipe is up here, on the engine end of the down pipe


https://mufflerexpress.com/products/...pair-2006-2010

SheckyB

Being I know the o2 sensor and wiper What is needed for the Fuel problem?Chevy.html

firemangeorge

Huh ?
I have no idea what you just wrote. Try some complete sentences with details.

whopper

wow - that makes absolutely no sense at all.

Lonwane

Shecky,
Please state year, engine size, codes if available, and completed description if issue as there are many items that can contribute to "fuel problems".
The more info, the better