For maximum/quickest results in carbureted, port fuel–injected, and throttle body–injected vehicles, a cleaner should be introduced either through the fuel rail or by manifold vacuum induction. Berryman B-12 Chemtool Through-Rail Injector Cleaner (part #s 1120 and #1126) will thoroughly clean fuel injectors, intake valves, and combustion chambers. Berryman B-12 Chemtool Total Combustion Cleaning Kit (part #2610) is an engine manifold vacuum–induced product that is applied via either the PCV valve or brake booster and will thoroughly clean intake valves and combustion chambers.