Posts by jvanabra
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Probably a doodad that reports the MAF is easier and cheaper than running a vacuum line from the dash board to the engine.
In the '80s when the turbo operated largely independently of engine management and was substantially less reliable, a turbo gauge was possibly informative.
In modern-ish cars where the turbo is a reliable component of comprehensive engine management a gauge is little more than entertainment. I don't have one in my Solstice or GTI and have never once missed it. Even in the 9-3 Aero I don't even remember a time where I've looked at it. The only time I specifically remember looking at it in the Viggen was when it was suddenly down on power - due to a MAF failure.
The number of times I've taken c900s apart to replace vacuum hoses in the dash is more than I'd like to count. The number of times I've taken 9-3 dashboards apart is zero.
In the '80s when the turbo operated largely independently of engine management and was substantially less reliable, a turbo gauge was possibly informative.
In modern-ish cars where the turbo is a reliable component of comprehensive engine management a gauge is little more than entertainment. I don't have one in my Solstice or GTI and have never once missed it. Even in the 9-3 Aero I don't even remember a time where I've looked at it. The only time I specifically remember looking at it in the Viggen was when it was suddenly down on power - due to a MAF failure.
The number of times I've taken c900s apart to replace vacuum hoses in the dash is more than I'd like to count. The number of times I've taken 9-3 dashboards apart is zero.
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That's correct.
It's hard to guess what a generic OBDII adapter shows. My Scangauge will display MAF in g/m and MAP in psi, but I have no way of knowing whether those are actual sensors or calculated values. I assume sensors but I don't know. This is an area where Tech 2 is helpful. It can also show MAF deviation, which tells you the variance of measured and corrected mass air... it's very helpful for diagnosing failures.
If you are actually getting 1psi, that is below base boost. The only way to get that is if the turbo's wastegate or actuator is defective or the engine is running real bad or there is a massive air leak. You can check the first with a Mityvac and a visual inspection. Second doesn't sound like it's the issue. Unhooking the W port will test the third, so would a smoke machine or intake pressure tester, either of which are the far safer options.
It's hard to guess what a generic OBDII adapter shows. My Scangauge will display MAF in g/m and MAP in psi, but I have no way of knowing whether those are actual sensors or calculated values. I assume sensors but I don't know. This is an area where Tech 2 is helpful. It can also show MAF deviation, which tells you the variance of measured and corrected mass air... it's very helpful for diagnosing failures.
If you are actually getting 1psi, that is below base boost. The only way to get that is if the turbo's wastegate or actuator is defective or the engine is running real bad or there is a massive air leak. You can check the first with a Mityvac and a visual inspection. Second doesn't sound like it's the issue. Unhooking the W port will test the third, so would a smoke machine or intake pressure tester, either of which are the far safer options.
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There's no electrical connector on the bypass valve...
There is an electrical connector on the boost control solenoid, and an electrical connector on the bypass valve control solenoid... I'm not sure which we're talking about.
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That is backwards.... the wastegate arm should move towards the actuator (opening the wastegate) not away from the actuator (closing the wastegate). It's really difficult - borderline impossible - to move by hand. I would maybe see if you could borrow a pressure pump (like a Mityvac) from an auto parts store if you wanna accurately test this.
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Are you talking about the actual wastegate or the actuator? The wastegate is part of the exhaust housing on the turbo... the actuator is a separately replaceable part.
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That turbo is done for... It will be out of balance and wobbly. There will likely be future destruction. You definitely need to check the inlet side. Something caused that. A missing blade will definitely affect boost... It's a hole for exhaust to go through that doesn't spin the impeller.
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It doesn't matter... That turbo is done for... Pull it out and replace what's broken... Hopefully just the CHRA. If you continue to run it it will wobble, blades will impact the housing, and you will send shrapnel throughout the engine. I would not start that motor one more time, personally.
It's definitely possible that what you're seeing is the result of something wrong on the compressor side that caused wobble and broke the exhaust impeller off on the housing.
You have less than base boost which means either the wastegate is open (you said it's not) or there is an intake leak preventing you from building boost or the turbo is damaged. We already know the latter is true.
Another possibility here is an intake leak, which caused a turbo overspeed, and that's what wrecked the blades. Pulling the inlet side off will tell you more, but you might as well pull the whole turbo off since you cannot continue to run it anyway.
It's definitely possible that what you're seeing is the result of something wrong on the compressor side that caused wobble and broke the exhaust impeller off on the housing.
You have less than base boost which means either the wastegate is open (you said it's not) or there is an intake leak preventing you from building boost or the turbo is damaged. We already know the latter is true.
Another possibility here is an intake leak, which caused a turbo overspeed, and that's what wrecked the blades. Pulling the inlet side off will tell you more, but you might as well pull the whole turbo off since you cannot continue to run it anyway.
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Half a mm is definitely normal. Do check out the hot side to be sure everything is intact, the swing valve moves freely, etc. Did the new turbo include its actuator? It so, I would test that with a pressure pump just to be sure the draphragm isn't ruptured. They're durable, but while it's easily accessible...
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It definitely shouldn't leak from anywhere, so I'd address that first. I agree there shouldn't be much overlap at TDC, but you can always rock the crank back and forth a few degrees to trim down on it. I don't think you will, but you could reach the point where you hear air escaping through the exhaust. That's of course fine - any other leaks need to be dealt with. Make sure you block off the PCV system, of course. The leak from the throttle body could be the o-ring on the top. They are often in poor shape.
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