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Boost pressure lower than it should be


El Andrew

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  • Member For: 8y 11m 5d
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  • Location: Canberra ACT

Exhaust place put an inspection camera through the exhaust and removed the dump, checked the wastegate, turbine housing, turbo bearings and exhaust manifold. Also checked what they could in terms of intercooler pipe leaks. Didn't find any issues.

I think I might try to make something up to pressure test, or get tested, my intake system.

Just a question on the wastegate test - if I'm disconnecting the line from the compressor housing so there is no boost reference to the wastegate, wouldn't that create a massive boost leak anyway?

Given I bought a new solenoid, I might just fit it anyway.

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  • Member For: 15y 11m 18d
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if you disconnect the line from the compressor housing to the wastegate, it'll overboost (if the system post-turbo isn't leaking out the extra boost created) and the turbo will boost as high as the mechanical pressure in the wastegate allows.

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I don't think a reasonable volume of air would leak out of that tiny fitting, compared to how much volume of air the compressor wheel is moving out of it's outlet, so yes, it would overcome it.

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Made up a thing and leak tested pressurised the intake system.

There's some hissing down in the front bar. Past Andrew left the hose clamps facing forwards, so I could get a socket through the grill and tighten but it didn't help. Think I'll have to remove the front bar and reposition some of the silicone joiners. At least I found something though!d0a9d51cb2822c7651277a10fb73ab21.jpg

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So a bit of progress with this. Over the past few weeks I've had the cat off the road tidying up a bunch of things, including replacing all of the intercooler pipe clamps behind the from bar with t-bolt clamps. Now tests fine for leaks.

 

The car still won't boost past 10psi. However now it holds 10psi, rather than just falling over. Made me suspicious I had two problems going on, so I started testing everything again, in case the boost leak was masking the secondary issue when I first tested.

 

And hey presto - disconnected the vac line from the compressor cover and had to jump off the throttle at 16psi.

 

So I'm thinking maybe time for a new wastegate?

 

Solenoid is new and I've confirmed it's not the tune (have checked it, haven't made any changes pre and post the problem and same issue if I flash in the 13psi workshop tune that was in it when I bought the car).

 

Edit: when I suggest wastegate, I'm thinking due to a weak spring and the wastegate opening too easily. As opposed to a wastegate failure causing the wastegate to stay closed.

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yeah, it sounds now like your wastegate is weakened and not holding how it should...

 

test it by taking the dump off and checking with a compressor to see when the wastegate creeps/opens.

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Looks like the genuine actuators are a bit rare too. Everyone sells the Turbosmart ones, but plenty posts about then being painful. Hopefully that's just an initial setup thing and once it is done and the WG DC fiddled with, would be ok.

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