In layman's terms, ignition timing is the delivery of the spark to ignite the fuel at the correct moment. The State of California requires that for applicable 1995 & older vehicles in Vista CA and Oceanside, that igniting timing be set per the manufacturer +/- 3 degrees unless otherwise specified on the under-hood label.
Top 3 reasons vehicles fail smog check for ignition timing
#1 - Incorrect setting/adjustment
#2 - Worn Components
#3 - Broken timing plate
Questions? Call (760) 691-2846