Spark Delay Timing Control: Description
NOTE:
On GLC 5-speed transmission equipped models, a transmission controlled spark system is also used. See
MAZDA TRANSMISSION SPARK DELAY TIMING CONTROL SYSTEM article In this section.
Spark delay timing control system is used on Federal GLC station wagon, California GLC models, and on all B2000 models. System is designed to reduce oxides of nitrogen (NOx) and hydrocarbon (HC) emissions by delaying vacuum to distributor advance unit during acceleration. A spark delay valve is located in carburetor-to-distributor vacuum line and delays vacuum spark signal for a short period when acceleration mode occurs.
On California B2000 models, a water thermo valve is also installed in this same vacuum line. This device will hold vacuum from reaching advance unit under any mode until engine coolant warms to 122°F (50°C) or more. This assists in catalytic converter warm up.