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The mkiv Supra Owners Club

Boost creep!


FOSTA

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Ok I had a problem with my boost spiking. It stuck open after around 2 months of use ( it was a 50mm non brand hks rip off with 5psi spring) and after I cleaned it up and unstuck it it seemed to spike real bad like from 5psi up to 8psi and 4.7-7psi. So every time I give it full throttle it would open at a higher psi level. And it was always higher than the spring rating!

 

So after playing around trying to work out what was going wrong I guessed it was the cheep wastage so I bought a new one. I bought a precision turbo pw46 wastegate 46mm cost around £300 with shipping and taxes from the USA.

 

So I fitted the new wastegate yesterday and fitted the 3psi spring and the 1.5 spring in the middle witch = 4.5psi spring rating. Now it will open every time at around 4.5psi to 4.7psi but creeps upto 5.2psi and 5.5psi if I keep the throttle open for a bit.

 

I replaced the vacume lines 3times and checked all fittings. I am running a AEM boost controller but it's turned off untill it's gets to the Dyno with ryan G ready to map the psi up to 8-9psi. So it's running off just the spring rating 4.5psi for now.

 

So my question is: is it normal for the psi levels to fluctuate slightly or should they stay at a solid psi level?

If it is ment to stay at a solid psi level what could be causing this to happen?

 

Thanks in advance jamie ;-).

 

Some pics of the wastegates:

 

The old 4bolt wastegate.

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The adaptor flange I had made and welded up.

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The new wastegate.

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Sweet! See I never took any notice when I first put it all together with the old wastegate. I noticed it opened at around 5psi and never took any notice of it after that untill it stuck open I started to pay attention. So I didnt know if slight creep was normal.

Cheers for that dude ;-)

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