Oil film in throttle body 97

[azee]

Hi, I have a 97, 4.3 with a rough idle in warm weather, problem seems to go away in cold weather. I went to spray gumout cleaner down the throttle body and noticed an oily coating mostly down below the butterfly valve. Has anyone heard of this? Is this normal? (I mean the oil).

[drewgibs]

are you talking about the black carbony build-up or is it something more? I've always had that black carbony build-up and figured it was normal...

[BlazerLT]

The oily film is from the PCV system recycling blow by back into the combustion chamber. Completely normal.

Clean the butterfly on both sides with a toothbrush and TB cleaner.

[azee]

Thanks for the info LT.

[azee]

Thanks for the info LT.