[srey]

I used a MityVac and did the exact same test the VehicularDIY guy did on his N54, T-ing into the vacuum hose that goes from the solenoid down to the wastegate actuator and starting the car to observie the pressure gauge.

Here's my question, though. After the engine goes through its warm up cycle and comes to regular idle (about 1:30 minutes) my vacuum on both go from ~15 psi to 0. That didn't happen to the guy in the video, but I also observed the gauge about 30 seconds longer than he did. So here's my question.

Should the vacuum from the solenoid to the wastegate drop to 0 after warmup at idle? To test I had my wife come out and bring the revs up to 4k slowly to see if the vacuum would build again. It didn't, but I'm unsure if the turbos would spool parked in neutral anyway. The needle didn't even move. If it's not supposed to drop to zero I think I found part of the cause of my lag issue. The wastegates might also be shot (115k miles, unsure if original turbos). I appreciate any guidance y'all can give me.

Edit - Video of me replicating the test.

[srey]

I guess I'll be able to find the answer next weekend. I just ordered new solenoids and will test them after I install them.

[srey]

The answer, in case you were wondering, is no. The boost solenoids should not drop vacuum to 0 after the warm-up cycle. I just installed my new ones today, and they never drop to 0. I am a bit concerned, though, because it appears they are holding 10-12 psi, and I swear I read somewhere that they should be doing 15.

[mweisdorfer]

Originally Posted by srey

I used a MityVac and did the exact same test the VehicularDIY guy did on his N54, T-ing into the vacuum hose that goes from the solenoid down to the wastegate actuator and starting the car to observie the pressure gauge.

Here's my question, though. After the engine goes through its warm up cycle and comes to regular idle (about 1:30 minutes) my vacuum on both go from ~15 psi to 0. That didn't happen to the guy in the video, but I also observed the gauge about 30 seconds longer than he did. So here's my question.

Should the vacuum from the solenoid to the wastegate drop to 0 after warmup at idle? To test I had my wife come out and bring the revs up to 4k slowly to see if the vacuum would build again. It didn't, but I'm unsure if the turbos would spool parked in neutral anyway. The needle didn't even move. If it's not supposed to drop to zero I think I found part of the cause of my lag issue. The wastegates might also be shot (115k miles, unsure if original turbos). I appreciate any guidance y'all can give me.

Edit - Video of me replicating the test.

Did you get a code or check engine light prompting you to check your boost solenoids?

[srey]

Originally Posted by mweisdorfer

Did you get a code or check engine light prompting you to check your boost solenoids?

I got 30ff, but there were multiple contributors to that. The main culprit was a chewed up o ring for the hotside intercooler connection, but I noticed lag too, which prompted me to test the solenoids.

[mweisdorfer]

Originally Posted by srey

I got 30ff, but there were multiple contributors to that. The main culprit was a chewed up o ring for the hotside intercooler connection, but I noticed lag too, which prompted me to test the solenoids.

Did you replace your vac lines ?

[srey]

Originally Posted by mweisdorfer

Did you replace your vac lines ?

Yes. They were all new and double checked when I ran the vac test on the solenoids (where they dropped to 0 after warmup). I didn't touch the lines again until I put in the new solenoids yesterday. They do not drop to 0 in the same test. The only difference is the solenoids.