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A further, more detailed cleaning video can be found here    • Turbo / Boost Fault Free Fix. Cleanin...  
Although this is on a Volvo Euro3 163 D5, this valve is on millions of cars from many manufacturers.
Improve turbo response and cure overboost with this simple fix.
Boost before was 20 psi with uneven delivery.
Boost after is 17 psi max with improved low down response. As an Amazon Associate I earn from qualifying purchases. Using my Amazon links does not cost you any extra.