According to the emissions manual, the BVSV's have the following duties:
BVSV1: disables purging of the EVAP system when engine is cold and disables spark advance when engine is cold.
BVSV2: disables Exhaust gas recirculation when engine is cold and disables choke opener when engine is cold.
bypassing BVSV1 would allow purging of the EVAP system when the engine is cold probably causing lean condition at low engine temp. Spark advance would be enabled when engine is cold--i'm not sure what this would cause.
bypassing BVSV2 would always have EGR active which would cause stumbling problems when cold and the choke plate would always be open, causing a lean/normal condition when the engine needs a rich air/fuel mixture.
Both of these valves are meant to improve how the engine runs when it is cold. depending how cold it gets where you live, and how long you let your truck warm up before you drive, bypassing these valves may be problematic.
ok thank you mbb, i got bvsv 2 hooked back up right. bvsv1 will have to be put in the shopping cart with the new radiator i suppose. unless i can successfully glue the nips back on this truck is on small thing after the next but i know a lot about it now.