I failed my smog pretest yesterday so the mechanic performed a throttle body cleaning and fuel injection system cleaning and I passed with flying colors (went from near the maximum levels to at/below average levels)

I understand the ful injection being an issue, but I was just wondering how the TB could affect things other then improve airflow slightly and response (which has nothing to do with emissions) . I can't image it can get enough crap building up in my TB to really affect things.

Anyone have before and after pics of TB cleaning?

 

My guess is that the clogged TB made the engine run richer than normal due to the less air flow...then again, there are many things that can cause you to fail