Rough idle on cold start

[Ck owner]

Problems exist only when started cold after sitting overnight.

I have an 09 Sierra Denali with th 6.2 and it starts rough, tach jumps a bit but then it clears up in 3 seconds. I cleaned throttle body and it is better but not perfect. Also if you have cleaned your throttle body and no major improvements, you may need to do a relearn on your intake. This has to be done at dealer. Mine is still not perfect as it was the first three years on cold starts. The dealer said not to worry its normal. Mine never threw a code yet. Been running premium and nothing else. Anyone find a direct solution?

 

[Bill325]

This may not apply to your vehicle, but anyone with a mass airflow sensor in their intake should take note. There's a GM service bulletin that warns that over oiling of washable aftermarket air filters can leave oil deposits on the MAF sensor, and cause problems.
Just an interesting thing to keep in mind.

 

[Ck owner]

Thanks for the input. I use a wix filter and have carefully cleaned the MAS. Thanks. Still not sure exactly what does it but it may be the fuel.