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The mkiv Supra Owners Club

Strange Boost Issue on NA-TT Conversion


Timlowthian

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Looking for some help with a few teething issues I'm having after converting my car to a Twin Turbo.

 

The car fires up and runs absolutely fine but it does have boost issues.

 

When you first start the car and go for a drive the first turbo comes online and makes 0.5 bar (which after research I think is normal for bpu?), after a few minutes and times of coming on boost it then just randomly stops making boost at all. The strange thing is if you then turn the car off and leave it a few minutes and jump back in and drive the 1st turbo will then work again for a few minutes and then stop.

 

The next problem is the second turbo has not come online at all, although i am unsure if this is because of the first turbo problem.

 

Has anyone come across this before?

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Did you inspect the VSV's? Check to make sure they are all connected (vacuum lines and connectors)

 

In my conversion, one of the VSV's were broken and had countless boost issues. After that one vacuum line kept popping out leaving me with only 7psi (0.5bar) so I had to change the hose and added a tie strap to hold it in.

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Well I have it running in TTC mode at the moment and its not really changed much still hit or miss if the boost comes in, it did get to 0.6 bar tonight though unlike the usual 0.5. If it was boost leak surely it would not get boost all the time instead of getting boost sometimes?

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Any of your mates has a Supra so you can try their VSV's before buying one? You can also try having it plumbed for TT but remove one vacuum line for the "top" VSV (Can take pics to show you what I mean). When I did this, my car only worked with the first turbo to 0.5-0.6 bar.

 

What it seems like so far: either VSV not working, causing secondary turbo no not engage, or secondary turbo itself is faulty (hope it's the first one)

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Well i have been out and changed all the lines and checked the intercooler pipe and no change. Put it back in to TTC and tried again and no change again.

 

I have a feeling however the second turbo is the cause of my issues. When I accelerate and then come of the throttle I am noticing white smoke from the exhaust (cant tell if its white or blue as rear window is tinted but its a light colour!)

 

Does this sound consistent with a blown second turbo?

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