Description & Operation
All Honda engines have ignition control systems to lower emission levels, maximize fuel economy and improve engine performance. The system is designed to advance and retard ignition timing as necessary.
Vehicles use a distributor advance with 2 separate vacuum diaphragms. See Fig 1 . Diaphragm A operates on intake manifold vacuum. Diaphragm B operates on intake manifold vacuum via an inline thermovalve. During cold engine operation, thermovalve B allows vacuum to enter diaphragm B to improve engine performance.