Sputtering, very rough idle and wants to shut off

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SteveandKish

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2010 Tahoe 380k KM- changed the injectors, MAF, throttle body, spark plugs, 02 downstream sensors, purge valve yet it still has rich banks on both banks, hard start sometimes have to touch the gas pedal for it to start, idles very rough and sputters like it wants to shut off, smell of gas, black soot out the tailpipe not sure what else to do, any thoughts I need help please
 

Fless

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Welcome to the forum from snowy Colorado!

How old (years/miles) are the upstream O2 sensors?

What's the KOEO fuel pressure? And when it's running?

Any modifications to the air filter, intake, etc.?
 

Joseph Garcia

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Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving clarifying questions from the knowledgeable folks on this Forum.

Do you have a quality bi-directional scanner? The scanner would help you identify the source of your issue.
 

j91z28d1

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did you change all that after it started running badly. or before.
 

petethepug

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Welcome from SoCal. I’m guessing you’re up North. I see you’re just getting it broke in. Three things come to mind…

Rotting battery cables from inside out. Regardless of the exterior appearance, change them if you never have.

This …
AB9E5488-3B28-4BF1-9473-2CA5007566BF.jpeg

And lastly that dreaded carbon canister under the truck. Replace it and verify if it’s mesh screen broke down and let carbon pellets into the fuel system.
 
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SteveandKish

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Not running E85 I only use 88 or 91 octane also we changed those parts after it started running badly
 

Fless

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Get a good scanner on it that can read what the fuel alcohol content is. Some of this gen had issues with the calibration that mis-calculated the alcohol content and that particular issue causes richness. There's a TSB on it, somewhere.

If the alcohol content as read by the scan tool is high, use it to reset the alcohol %, and look into getting the calibration updated by someone who can program GM modules.

 

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