[mj6234]

I have oil in my vacuum lines and all the vacuum disappears maybe 10 sec after car shutoff. I have individually tested all the lines and vacuum canisters and all seem to hold. I strongly suspect it is the check valve coming off the vacuum pump has failed after 179K miles.

Has anyone found a way to replace this check valve? I cant find anywhere that it is sold separately without buying the pump.

As a side note, my WGDC values are higher than they should be. I have checked literally everything (pressure tested intake tract, smoke tested vacuum side, used a boroscope to confirm the WG flappers are sealing, made sure the WGs hold vacuum and no diaphragm leak, checked DVs, etc) and still slower than expected spool. I did do some pulls with a boost gauge connected at the vacuum canister outlets and the vacuum levels seem consistent around -25 to -21 inHg.

I feel like maybe the vacuum pump is weak or the check valve issue might be causing this. I also noticed it takes the outlet of the vacuum canister like 8-10 sec to reach full vacuum of -25inHg at idle, which seems slower than I expected.

I have upgraded turbos, flex fuel, Reflex+, N20 map, scaled tune and all of that. Current state cant get past 21-22psi or so even with max WGDC. No throttle closures or anything like that.