I'm running out of ideas on this one, so I'm throwing it out to the group for help. A few months ago, I picked up an 03s with 130k on the clock. Po bought it with a bad head gasket, had his friend (a BMW mechanic) repair that, also found supercharger was shot. Sent it to Dustin at stateline for a rebuild, slapped it in with a 15% pulley, just started driving it and found out he had stage 4 cancer. I picked it up from him in June and have been driving it since.
Aside from the pulley its stock. I decided to add a boost gauge and I'm only seeing a max of 10psi, and it starts around 6psi ar lower rpms. With the pulley, I understand I should be up near 15 psi or so?

so in my quest to correct it, I've done the following:
-checked pulley isn't slipping on sc shaft, replaced belt
-checked bpv function with vac gauge, adjusted set screw so it closes pretty well
-pressure checked from throttle body to head. Looks tight, changed out a bunch of gaskets that were leaky or questionable(intake mani, mani horn to ic, ic boots, injector o rings, throttle body gasket, sc inlet)
-tried vgs mod to see if it helped. No real improvement.

at this point, I'm about out of ideas. Last few thoughts:
-supercharger not producing enough boost (but Dustin seems like the go to guy for rebuilds)
-bpv leaking back into intake tract (looks like it seals ok visually, but I dont know how tight it should seal?)
-withcraft or bad juju from rocking Japanese cars my entire life until now.

any ideas? She runs good, but I feel like I should be getting more from it and its driving me nuts! Thanks all!

 

Guys, since the last post I have changed out the crank pulley as it was looking pretty tattered and I feared it might be failing, however that didnt fix it. Still cant get beyond ~10psi.

I'm losing my mind here. My last few guesses, which I really dont want to just shotgun because I'm tired of spending money:
-bpv leaking by, even though it looks and behaves correctly
-belt slip due to tensioner issue? Not sure how to test this
-bad supercharger rebuild, which again seems unlikely

anyone have any thoughts at all? I know this car can do more and its killing me not knowing what's wrong...

thanks!!

 

 

it runs very good. Having not driven this car before the repairs or another r53 in good shape, I cant say how it compares as far as power. Boost hits quick and hard, no codes, no stuttering, it runs good, just feels like it should be a bit stronger in boost, and the 10psi max kinda agrees with that. Would love to put it side by side with a good running r53 either stock or with just a pulley for comparison, but I dont know anyone local with one. Northeast PA isnt exactly brimming with them...

thanks!

 

We've seen improper rebuilt superchargers only make 10psi before. So I would be checking that.

 

 

I teed in at the intake mani, although that is tied to the fpr line also. Also verified boost gauge using torquelite and my obd2 scanner - boost from the app shows within 0.5 psi of the gauge at all times.

 

Thanks Way - any idea how to test that? I'm going to call the rebuilder later and talk it over with him as well.