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need help diagnosing turbo problem... Posted by michael [Email] ![]() ![]() |
'91 900tc.
adjusted basic boost yesterday. was running great, boosting just up to the red (up from about 3/4). after flooring it early and often, the boost abruptly died. now, when i get on the gas hard, it pulls until just into orange and then stutters; it's accompanied by a strange noise, almost metallic, which continues until i let off the gas. if i accelerate less than full throttle, i'll be able to get well into the orange before the same thing happens. this happens with the solenoid unplugged as well; it doesn't get anywhere near even basic boost. i've checked around the hoses pretty good--ic, turbo-ic pipe, all the little vacuum lines, and every thing seems ok. any ideas what this could be, and how to better diagnose? the suspects:
1. wastegate: this seems the most likely, aside from a huge ass air leak. either sticking open, or perhaps leaking from the gate itself? the spring seemed pretty strong when i was adjusting, but what do i know?
2. solenoid: i'm not quite sure how this would do it; if it were busted, i should still get basic boost, right?
anything else? by not getting basic boost pressure, i can only think that i have a leak that i'm missing (maybe turbo to exhaust mani? does this happen? how to check?), turbo failure (but i get boost if i'm gentle with the throttle, which doesn't make sense; also, i'd think there'd be more noise at all times, no?) or wastegate.
this is tough to test because revving the engine in neutral doesn't give me any boost, so i can't hear where the noise is coming from.
posted by 68.11.50...
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