12psi but NOT an installation issue
Jun 5, 2011, 12:26 PM
#34
So, you state it is not an install problem, and that the turbo is in good condition, you've done a boost leak test, the wastegate puck is functioning properly, and I am assuming that the MBC is hooked up properly. Then the problem is in the WGA, or the MBC.
The best way to eliminate the MBC as a possible cause is to do the test which I outlined above which removes the MBC as a variable in the equation. The method I indicated will also let you know if your WGA is functioning properly because you will be setting peak boost directly via the WGA's adjustable actuator rod.
You are assuming that your MBC is working properly and you are assuming that your WGA(s) is/are functioning and is set up properly to work with your particular combination.
Just because you install a new Forge WGA and give it a few turns does not mean that there is enough preload or that it is set up properly.
The best way to eliminate the MBC as a possible cause is to do the test which I outlined above which removes the MBC as a variable in the equation. The method I indicated will also let you know if your WGA is functioning properly because you will be setting peak boost directly via the WGA's adjustable actuator rod.
You are assuming that your MBC is working properly and you are assuming that your WGA(s) is/are functioning and is set up properly to work with your particular combination.
Just because you install a new Forge WGA and give it a few turns does not mean that there is enough preload or that it is set up properly.
and for the wga, we adjusted the preload in 3 turn increments until we maxxed out the adjustment on the arm
Jun 5, 2011, 12:44 PM
#35
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Its a good possibility that when you ran it with the IC pipe off you overspun the littly stock turbo with 80k on it and its in its final days of boosting at all.
Jun 6, 2011, 07:25 PM
#37
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Update: we pulled the turbo tonight and found oil in runner #1. When I drained the coolant yesterday I was pretty sure I saw some oil in there coming out of the lower radiator hose but wasn't sure. I'm also a n00b and brushed it off. Well, combined with this symptom, we're thinking head gasket (maybe ring).
Compression and leak-down tests coming up Wednesday. Stay tuned
Compression and leak-down tests coming up Wednesday. Stay tuned
Aug 18, 2011, 04:59 PM
#42
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Update v4.6092Beta: The head did not fix the issue, leaving the turbo as the only thing unchanged through this whole debacle. I had the valves refaced, new seals, decked, vacuum and pressure tested the head and same old symptoms. I pulled the turbo the other night and picked up a used 8 turbo with a 10.5 hotside in the classifieds that will be here in a few days. This has been pretty frustrating trying to diagnose. The turbo never showed any obvious signs of failure. There's no shaft play, no smoke, no noise. We shall see...
"It's the turbo, Brian, it's always been the turbo..."
"It's the turbo, Brian, it's always been the turbo..."
Aug 26, 2011, 08:06 PM
#43
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Or not. Bought an VIII turbo in the classifieds and still no boost. It does seem to spool faster but won't go past 14 or 15psi. Changed the wastegate from the Forge to the stock one just to re-rule that variable out, no dice. Another round of compression and leak down tests are in order, but this is ridiculous!!!
