trymes Posted September 8, 2017 Author Report Share Posted September 8, 2017 So, I pulled the actuator, inspected it, and swapped in a lower PSI spring to see what would happen. Basically, the behavior is the same, but now at lower ratings (builds to 8-9PSI, then drops down to 2-3). The good news is that the boost pressure doesn't creep into the danger zone now, but it means I'm running really low pressure, which doesn't lead to breathtaking performance. On a positive note, I am getting a handle on the oil leaks, but I think it may be a very short lived triumph. Quote Link to comment Share on other sites More sharing options...
Bean Posted September 9, 2017 Report Share Posted September 9, 2017 Have you played with an air pump to see how preload affects it? I wonder if the piston Mamba actuator is better suited for newer cars with ECU controlled boost? I'm also wondering if that boost spike you see is it overcoming any stiction before ot moves? If you had something like an AEM Tru Boost - the solenoid would keep boost at whatever you set, and when it goes over the actuator only sees 10psi and the controller opens and shuts the WG quickly to maintain boost. (Spring strength is to ensure the wastegate flap doesn't blow open from boost - Stock Volvo actuator open at 4.5 psi for instance when it sees boost direct.) I know Volvo guys have said good things about Mamba WG actuators - but newer Volvo's use an ECU controlled solenoid set up. Rabin Quote Link to comment Share on other sites More sharing options...
trymes Posted September 9, 2017 Author Report Share Posted September 9, 2017 Maybe, Rabin. I'm thinking it might also be an artifact of the crankcase pressure I'm seeing, too. I picked the Mamba over other options just because it had the most choices for rod length. Ironically, I'm almost all of the way out of adjustment on the second shortest, and the next longer is too long. The folks at Mamba have suggested possible air leaking around an O-ring, but that seems unlikely to me. I also disassembled the unit to confirm that the piston is well lubricated, and it is. Testing with an air pump shows smooth action, and no leaks, whatsoever. Quote Link to comment Share on other sites More sharing options...
Bean Posted September 9, 2017 Report Share Posted September 9, 2017 Do you have your boost gauge hooked up when testing? I use my compressor with the regulator cranked way down to 15 -20 psi so that the actuator gets a burst of air that it then reacts too. Rabin Quote Link to comment Share on other sites More sharing options...
Goce Posted September 9, 2017 Report Share Posted September 9, 2017 Sounds like an intake gasket leak, under vacuum is fine, but under boost leaks. But 9-3 psi is too much for a leak alone, check for boost leaks. Quote Link to comment Share on other sites More sharing options...
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