D-Karbonizer 4 Intake System Cleaning When you need serious intake system cleaning, you need our D-Karbonizer 4 fluid. It quickly strips away carbon, gum, and varnish. A clean intake and combustion system results in easier starting, less engine knocking, better fuel economy, and fewer emissions. We recommend it for all of our canister-type cleaning devices. No mixing; use right from the can. No. 7904A D-Karbonizer 4 intake system cleaning treatment. Case of 12 16-oz. cans.