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Discussion Starter · #1 · (Edited)
Hey guys and gals,

Long time creeper, first time poster. I currently have a 2011 silverado 1500, with 163,622 miles on it. It's a 5.3 vortec engine. It smokes from the exhaust a light blue exhaust that's mixed with a grey/white exhaust. It stops smoking after roughly 10 seconds of running. Haven't noticed it while driving. It also doesn't smoke every start-up. It rough idles when in park. I replaced the plugs and wires a couple weeks ago, and I started misfiring on cylinder 8 after the change, before the change it was cylinder 5. The only codes it's thrown is for the misfiring. I also pulled plug 8 after the codes to check it and found oil on it. I did a combustion gas leak test and the liquid stayed the same color (blue). I'm starting to lose my mind. Any thoughts, suggestions to try? Also, as of now....I've noticed no loss in power at the moment.
 

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Sounds like maybe bad valve guide seals. My guess is you only see it on startup when it's been sitting overnight or for several hours. What your seeing is the residual oil that leaked into the combustion chamber while sitting burning off. Usually that smoke will clear up after about 10-30sec of running. It might be running rough if the oil is slowly fouling the plugs out, or your coils are failing.
 

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In the old days we'd increase the plug heat range to prevent tip fouling.

Try a compression check to see if there is any cylinder or ring damage
 

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many new GM 5.3L engines fail because of the AFM engine cylinder control . probably a $7,000 fix ..
 
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