Thread: Gtir T28 Not Holding Boost?

My issue was with Vadim's statement that weak springs can cause a leak during a boost leak test. I have a gate valve on my air supply line which I close after pressurizing the system. On a well assembled system the pressure will usually hold pretty well.

C

gotcha.. maybe i should test mine again lol

Alright no need to BenFenner me


Your other statement is true, I'm not thinking straight (running on 2 hours of sleep).

What's the average pressure loss per second? I thought I saw people say 1 psi per second, bu that seems a little too fast.

It's like pornography. You may not be able to define it, but you'll know it when you see it.

When I tested my current turbo setup, after curing the obvious leaks, it still bled down quicker than I'd like. But I was running short on time (it was the night before hitting the road to this years convention), and I haven't gotten back to it again for further diagnosis.

My turbo NX held pressure like a champ. I'd venture to say it didn't leak down at all, but hesitate to do so since it's been a few years, and the old bean just ain't 100% in the memory department.

I've found over time that having a simple shut off valve on the air hose is very valuable, because it allows you to seal the system after pressurizing it, and let's you turn off your noisy air compressor, so you can hear leaks easier. Also, with no valve, you're always pumping air into the system which causes its own noise. Once everything in the garage is silent, and no air is flowing, you can go Zen on the car and pinpoint those last few leaks.

C

Where are you pressurizing the system from that you have no leaks Chris? An intake/exhaust valve being open will certainly cause leakdown.

I have an 8 gallon 200psi compressor. I was able to pressurize the whole system to 15psi 5 times before the compressor even kicked on. That was enough for me to hear the leaks, fix and refill. Soapy water works wonders too. That's how I found out my turbo comp housing wasn't sealing all of the way.


Also I removed the MBC, back to wastegate pressure, spikes to 9, levels off at 7-8. This is enough boost for Autocross tomorrow, I'm spinning the new tires even in second gear, but they are silent. I guess I bought these for auto-x (stiff sidewalls) not for drag racing.

I had a similar issue, it turn out to be the GTiR wastegate was leaking, they are old as hell if they were never replaced. I could not pinpoint the issue with a leak test. I blew thru the wastegate orifice and air was escaping inside the diaphragm.

By the way I have an almost new ATP wastegate actuator I can sell if you need it.

Last time I blew into it, it wasn't leaking, but then again mouth pressure is not as strong as boost