Data logging boost, intermittent high reading

[whizz371]

Hi All.
As above, my boost is not generally high , but it does spike as I lift off I am assuming this is because it is waiting for the dump valve to open. Can anyone tell me if this is normal please. Very new to turbo car , but getting there. I am using Vcds.

 

[Stuart B]

It's not really intermittent is it - there's a pattern to it. The throttle plate closes so there's nowhere for the excess boost to go until the charge circuit goes from positive pressure to vacuum, and frees the air.