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Discussion Starter · #1 ·
Ok, so I thought I sort of understood how external wastegates work, but I really don't get what is happening here...

I have a fairly old Innovative Turby wastegate, 40mm I think, on a cast manifold. With the adjustment screw backed out all the way, the boost will go up to 29 psi. I want to run 36 psi, so I figured I'd just tighten the screw a bit. However, the boost goes DOWN when I tighten the screw - Actually, more accurately, the minimum boost goes up, but the max boost drops.

With the screw on the loosest setting, I can run 5 psi all the way to redline. With the screw tightened down, my minimum boost is more like 22 psi, and my max boost is 24 psi (instead of 29).

I was confused so I was like whatever and got a stronger spring off ebay. I put it in, and now the max boost is 24 psi and and minimum boost is 15 psi, except the turbo spools super slow and I can hear that the wastegate is open ALL the time... at least I think that's what I hear. I can definitely hear air rushing out, but I don't think I have any boost leaks. What the heck?

I have a Blitz DSBC boost controller. The I have a vacuum line going from the turbo compressor housing to the IN of the boost controller solenoid and also T'd off going to the MIDDLE of the wastegate. I have the output of the boost controller solenoid going to the TOP of the wastegate. This is how I've had it for years and it's been working fine till lately, so I think it's right, but please verify.

Also, I just unplugged the vacuum line going to the middle of the wastegate and capped it off temporarily, so it should have a real hard time opening I think right? It's STILL doing the same thing - Max 24 psi and air rushing out.

Do these symptoms make any sense to anyone or is my WG just totally jacked up? I don't see how adding more spring pressure can LOWER the boost. I've had the WG apart a couple times now and it looks fine instead... no obvious problems (to me) anyway.
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