Hi all, I have a question regarding emissions at smog check while running a add-in fuel system cleaner.
My problem is a recent CA smog test failure. California has the two stage test as most know, and emissions were a little over on the low speed test, in hydrocarbons. 25 mph was fine. Problem is an intermittent miss. Why the test was underway I could hear a little miss every now and then. Tech was going re-test, but decided to have me clear up the miss problem first. I have no idea why it decided to start the miss, truck runs great. I previous did a pretty complete tune-up. Isolating the miss is next to impossible; random rpm or none. So fixing that is not really an option (it's very very minor and usually non-existant).

The question: If I run a bottle of Valvoline Complete Fuel System cleaner in the gas during the next test, will the cleaner increase the normal emissions? I ran some a few weeks prior to the test and the truck ran flawless with the cleaner in it.
What do these chemical treatments do as far as extra pollutants?
Any smog techs have any thoughts on this?