Originally Posted by beamishken
Seeing a vacuum in the manifold isn't as daft as it sounds.
A none turbo naturally aspirated engine would see a vacuum in the manifold as the cylinders pulled the induction air in,
If your turbo isn't working and the engine requires more air than the turbo can provide then it is possible to see a vacuum in the manifold
That said I'd expect performance to be down further than your experiencing
Let's wait and see what a new gauge with the correct range has to say
Yes I understand that, only when I take the hose off the intercooler and physically plug with my hand and engine running flat out the pressure is to strong for me to create a seal, but when I take the boost gauge valve off the manifold and and run same rpm I can plug hole very easy.
Will try and take pics of what I'm doing, will keep you posted 😀