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Discussion Starter #1 (Edited)
After watching DRE Dan (Extreme Revolution) on Youtube discus pressure leak down testing boost & vacuum system, I set up a pressure gauge in a similar fashion to that shown in the video.

https://www.youtube.com/watch?v=heQYgmcGnHI&t=176s

Another user informed me that max boost pressure under acceleration was about 15 psi, so I pressurized my engine to 15 psi and timed it's leak down to 5 psi at about 17 seconds. Throttle body gasket was hissing loudly, but the fasteners are torqued to 71 inch-pounds as per AllDataDIY spec. The gasket is the new one that came with the new intake manifold. My engine has about three hours on this manifold and maybe two hours on the new turbo. I noticed BNR offers the MAHLE Throttle Body gasket with their TB Spacer.

BNR Throttle Body Spacer - LUV/LUJ 1.4T

The BNR pic shows the MAHLE gasket as being a bit wider and thicker than the AC Delco 55566665 TB gasket, IMHO. Rock Auto offers the MAHLE G32637 gasket for less than $4. Has anyone had success solving a TB to Intake seal vacuum - boost leak using the MAHLE gasket?

https://www.rockauto.com/en/moreinfo.php?pk=6998708&cc=1446770
 

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Discussion Starter #2 (Edited)
I ordered the MAHLE gasket and will get it next week and install next weekend. (It's not available at Oriely, AutoZone, NAPA, Advanced Auto, or PepBoys and Amazon is out of stock.) My engine's long term fuel trim is running about 12 at idle, so the PCM is holding the injectors open too long and unburned catalyzed fuel is dripping from the tail pipe. I will not run engine again until it passes leak down and maybe smoke testing because I don't want to buy new Cats.
 

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Discussion Starter #3

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Finally quit raining, and I took advantage to install the new MAHLE throttle body gasket. It's definitely thicker and wider than the ACDelco gasket, and it seals better. I ran the engine after reinstalling the throttle body and properly torquing the mount socket screws back to 71 inch pounds. After it warmed up the long term fuel trim stabilized at about 7.8. I then ran the heat full on for ten minutes and then the AC full on for ten minutes. Then I ran the rpms up to 2500 for two minutes; LTFT went down at higher rpms. The LTFT then restabilized at about 9~ish back at idle. There's still a vacuum leak, and I think I'll have to retry the propane and water spray tests. If that fails, then I'll set up the charcoal smoker can and smoke test it. I'll do another pressure leak down test in the morning. It's forecast that the rain won't start again until Sunday afternoon.

And the trunk seal along the bottom lip adjacent to the latch is leaking. The fiber pad under the spare tire in the spare tire well was soaked after last night's heavy rains. I need a cover for this car. I should have thought twice about converting the garage into an office. A nice bead of RTV should seal the leaky trunk gasket seal.
 
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