Bronco Full Size V8-302 5.0L (1986)
Normally Open Air Bypass Valves without Vacuum Vent -Heavy Truck Applications
Normally open valves without a vacuum vent provide a timed dump of air for 2 seconds nominal when a sudden high vacuum of about 68 kPa (20
in.-Hg) is applied to the signal port. This prevents backfire during deceleration.
Normally Open Air Bypass Valves (9B289)-Heavy Truck Application
Normally open valves with a vacuum vent provide a timed air dump decelerations and also dump when a vacuum pressure difference is maintained
between the signal port and the vent port. The signal port must have 10 kPa (3 in-Hg) more vacuum than the vent port to hold the dump. This mode is
used to protect the catalyst from overheating.
