Emission Control Systems: Specifications

Evaporative emission check and relief valve:
Check valve opening vacuum 25.4-35.5 mmHg (1.0-1.4 inHg)
Relief valve opening vacuum 5.0-15.2 mmHg (0.2-0.6 inHg)
Canister purge control valve opening pressure 70-110 mmHg (2.8-4.4 inHg)
Purge hose vacuum to open purge valve 380 mmHg (15.0 inHg)
EGR valve operating vacuum:
Starting approx. 60 mmHg (2.3 inHg)
Wide open approx. 220 mmHg (8.6 inHg)
Signal temperature for EGR vacuum switching valve 50~C (122~F)
Back pressure transducer control pressure:
Off less than or equal to 53.5 mmAq (2.1 inAq) [1]
On more than or equal to 81.5 mmAq (3.2 inAq) [1]

[1] mmAq (inAq) is used to represent pressure or vacuum measured by the height of a column of water which it supports. This convention is used when pressure differentials are too small to accurately measure using millimeters or inches of Mercury (Hg).