amaderojr

OK I've spent hours doing research and am not being able to figure this one out. I just bought this 90 300zx TT, supposedly rebuilt with like 500miles on rebuild. ( just some background info). So I put a boost gauge because it just didn't seem as fast as it should, (I also own a Galant vr4 awd turbo, and that seemed to pull harder) and it is only boosting 4lbs. So I went through everything and noticed that it was put back together without a destination sensor, so I bypassed it until I can get a relocation kit. So now I have a code 55 but still only boosting 4lbs, so I disconnect the safe boost solenoid on the wastegate and still only 4lbs. So I try unplugging and blocking off the waste gate vacuum lines ( and I know this is very dangers so I ran 100octane to lower possibility of detonation) and what do you know its pushing 15psi. (Only ran it the once). So I want to know if anyone knows why its only pushing 4psi with the wastegate vacuum connected? Oh yea, and I did a boost leak test.

NismoPick

Welcome to ZDriver!

Well, if you completely disconnected the wastegate vaccum lines, and it then runs higher boost, I'd say someone has messed w/ the waste gates. Were the turbochargers also rebuilt?

The easiest test would be to hook up a +pressure line and gauge (bike tire pump / hand pump) and watch the waste gate open. If they always open at 4psi, then you can adjust the arm to open at a higher psi... someone might have taken them apart, and didn't re-calibrate the arms for the correct psi.

Of course, working on Z32 turbochargers in the engine bay isn't fun.

amaderojr

Oh that's a good point, I'll see if I can't get in there and try that out