BAD, TVS Purge manifold sensor?

elcotrk

Not-quite-so-new-guy
Oct 8, 2021
22
3
86 Elco, 5.0
rough idle seem like vacuum leak everything else good.
Has two manifold sensors EFE TVS, located on driver side by T-housing and the Purge TVS is on the passenger side of T-housing. Purge TVS is suspect of a vacuum leak. checking it when engine is cold it is open, air flows through, I'm thinking it should be closed when cold. engine stalls when cold unless chocked, idles rough when warm. Anyone have a heads up on the question?
Should the Purge TVS be closed when engine cold? not allowing vacuum
thx
 

k24556

Not-quite-so-new-guy
Oct 5, 2021
8
3
I don’t have any experience with OBD-1 systems. The GM OBD-2 (1996 and later vehicles) have the purge solenoid energized once the engine goes to closed loop (warmed up and all systems go). If the purge valve is open all the time, the engine will go lean because all the fumes from the charcoal canister are pulled out. So as an uneducated guess, I would say the “older” system is similar, so your TVS solenoid needs to be closed until the pcm commands it open. If your TVS has an electric al connector, then you can check to see if there is a signal going to it.
 

elcotrk

Not-quite-so-new-guy
Thread starter
Oct 8, 2021
22
3
Thx,,,the reply is helpful for me in checking the issue, confirms my thoughts that it is bad, finding another part is going to be tough it’s a discontinued thanks again
 

k24556

Not-quite-so-new-guy
Oct 5, 2021
8
3
Some purge solenoids have hose barbs on both ends. Then you could place a switch to activate an electrical purge solenoid once you are warmed up and going down the road. I think your purge valve may be vacuum actuated, so if you go this route, you will need to plug the actuation line if you do this.
 

elcotrk

Not-quite-so-new-guy
Thread starter
Oct 8, 2021
22
3
Some purge solenoids have hose barbs on both ends. Then you could place a switch to activate an electrical purge solenoid once you are warmed up and going down the road. I think your purge valve may be vacuum actuated, so if you go this route, you will need to plug the actuation line if you do this.
 

elcotrk

Not-quite-so-new-guy
Thread starter
Oct 8, 2021
22
3
Thanks for your reply, helpful,,,
Purge TVS switch (front pass side of manifold) is controlled by coolant only not electrical, but there is another purge sensor switch which is electrical & vacuum mounted passenger side rear engine when charged/discharged allows vacuum to open/close that one has been replaced new
 

elcotrk

Not-quite-so-new-guy
Thread starter
Oct 8, 2021
22
3
FYI,,, replaced old Purge TVS . New TVS is closed when cold at startup. Old was open at cold caused vacuum leak
 
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