Engine light on and runs rough

[liftlawssuck]

Hi Guys,
I have an 05 Tahoe with a 5.3 that has an check engine light on. I have PO131, PO171, PO300, and PO102 for codes that were pulled. The symptoms are that it will run rough sometimes at idle and the exhaust smells really bad. It started about a year ago but then it was every so often and didn't throw a code. Since it has been getting worse. Now the light is on.

With 165k mile on I decided to change the intake gasket. Didn't notice any tell tale signs of leaking when it was off but changed it anyways. I also replaced plugs and wires.

When I pulled the plugs I noticed the drivers side all were black like running rich. The passenger side was nice white looking. After changing all the above it still runs the same way.

Any thoughts??

Thanks, Brian

[WrenchTurner]

Same issue I'm Having... Subscribed

[liftlawssuck]

So I found a thread on here from 2010 that has the exact same symptoms of mine. Course I can't find it now. But I changed the O2 sensor on bank 1 sensor 1 as that's what he did and so far so good. Check engine light is still on but it runs normal again. Hopefully light will go off on it's own. This was after checking for vacuum leaks and feeling good about not having any. Time will tell.
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[WrenchTurner]

Hope that takes care of it alot of information on the web with no smoking gun for what fixes it. So far Ive done the easy things Fuel pressure regulator fuel rail vacuum hose for for fuel, gaskets for air leaks, R2 Mass flow Sensor.

[liftlawssuck]

Well I think it's fixed. The engine light went out last night. One of the tell tale sign for me was the driver side plugs were all black and the passenger side were all nice white. So that told me that a fuel injector nozzle most likely wasn't it. It was something common with all plugs on 1 side. With engine running have you sprayed carb cleaner or something similar around all intake ports? If engine changes the way it runs then you have found the vacuum leak. If all is good then I would pull plugs and look at them. You will be able a lot from the plugs if something is wrong. If only 1 plug is bad looking then it is something isolated to that cylinder. Hope this helps! Keep me posted and we'll get it!

[WrenchTurner]

Removed the plugs yesterday, they were all white I did notice they were gapped to .060 I have read GM came out with a service bulletin for .040 not sure when these plug were changed last so I'll pick some up today. Tried the carb cleaner looking for air leaks but didn't find any.

[liftlawssuck]

Depending on how well you are about troubleshooting. You might want to invest in a scanner. Then you can look a little deeper into the codes and each system. Sounds like it might more than the obvious. The parts stores can read the codes but they're pretty much useless unless you can scan the computer.