Wojo7

Has anyone had any trouble maintaining a steady boost curve with aftermarket exhaust systems? I have a 46 mm wastegate and can't seem to keep the boost from spiking unless I run a 10 psi spring , seems like if I run anything higher and the wastegate opens at higher rpm it doesn't really do a good job of slowing the turbo down. I am running a silencer where the cat would be and the wastegate tie in is before it, I'm thinking of moving the tie in to the downstream side of the silencer where there is less back pressure much like the factory exhaust. If I interrupt the signal to the wastegate even with the 10 psi spring I'll hit the overboost in the m tune. I've tested the wastegate and it seems to be working fine. Also this is a new issue since installing a 27/6.

ekoz

I recently had a similar problem. It coincided with an exhaust upgrade but had nothing to do with the exhaust. Turns out I had some crud in the manual boost controller. I took it apart, cleaned and reassembled and that solved the problem.

Wojo7

So I took the boost control out of the equation all together, I've got a direct connection between the banjo bolt and wastegate, the wastegate has a 15.9 psi spring in it, this is what happens, it was a lot worse when the boost control was involved. Could this be caused by exhaust turbulence? It seems like the wastegate is fluttering.

shortyboy

what are you using to control boost? manual boost controller? electronic ? stock cycling valve? in any case check the routing of your lines to the waste gate, they could be reversed.

Wojo7

So I pulled my waste gate and bench tested it, with a 15.9# spring it took 19# to even get it moving, most of the air was leaking through the stem, at about 24# continuous air it was 3/4 open. I changed to a 10# spring and it takes 16# to get it to move and just about 20# for about 3/4 open. The air is blowing past the valve stem the whole time. It's got less than 500 miles on it. Come to think of it I've been having boost control issues since I installed it but I've been blaming it on boost control, I never imagined the wastegate could be at fault. I also tested my stock wastegate, it does not leak any air past the valve stem and moves very smoothly. I've heard that some leakage is normal but I can't see how this much could be correct, not to mention I have almost no accurate control over boost.

JacRyann

The diaphragm is ripped on that wastegate. Shouldn't be leaking any pressure at all.