Need a lesson in Vaccum 101....

[Pats-GN]

This is to do with the check valves in the vaccum lines. Theres one around the EGR valve and one on its way to the fuel vapor canister, I think thats what its called. The valve around the canister pretty much works when it wants to. Its not leaking externally but internally, guess its got a check ball hanging. How does this effect the vaccum if these valves are inoperative? Is it similar to a vaccum leak? This is the only vaccum problem I can find, and my guage is going wild along with my idle and IAC's. If I plug the line at the valve everything is good. Would someone explain how this works, I'm too tired to figure it out right now

thanks in advance
pat

 

[SilverSleeper]

You should replace those valves if they leak internally. They should only floww air one way. You want the motor to pull air from those devices (vac.) through those, but not push boost back through them.
However, your leak is probably somewhere else, The valves should have vac. going through them, so it wont "flow more" than the motor can draw. I would check your lines to see if any are cracked, especially around the turbo, where heat gets to them.
What are your IAC readings at idle? They should be between 20-40 I think. Try using the reset procedure on gn-ttype.org and see how that works out.
HTH.

 

[Steve Wood]

I believe the purpose of the valve is to prevent boost from going to canister, egr, or ac vacuum circuits.

Take a pair of pliers and clamp the hose on the tb side of the valve and see if the problem stops, if it does, then go to the other side fo the valve and clamp off the line...if it does not stop, the problem is in the valve...if it does stop, then the problem is further down the line.

 

[Pats-GN]

Thanks guys