Renrag

I've just fitted a psi boost gauge to my P1. What pressures should I be getting and for what reason would the pressure drop below zero?

Thanks in advance to the techno guys for an answer.

Ian Cook

Hmm dont know what readings you should be getting exactly, but between 13 and 17 as a very rough guide.

You will get negative readings when you lift off the throttle as it runs vacuum (i think) it shouldnt drop below zero when the you have your right foot on the throttle, but take it off or back off and it will.

Renrag

Once again many thanks for your help Ian, you pointed me in the right direction. The problem was a boost gauge reading “0” with ignition off, “0” at idle, no change on revving and a max pressure of 6psi on maximum boost. Installed by my local Scooby dealer as I was concerned about the warranty. Having already had a major run in with International Motors over warranty on using the car for track days I was erring on the cautious side.
So £60 of labour I end up with a boost gauge that is screwed into 1/2mm of plastic, on the most curved part of the dash (so it wobbles and has fallen off once), with the cables bound in ugly electrical tape and doesn’t work! Not bad eh for £60?
Next step after your reply was a visit to my local genius (he looks after my Westfield) and two minutes later, a bit of humming and harring and a few swift hose reconnections I have the following:
0psi engine off, minus 10psi on idle, on revving moves to zero and on boost runs to 16psi. So thanks to you Ian and my mate Tony at ART in Wakefield “it works”!
Next question – any one know of a decent Scooby mechanic in Yorkshire so I can maintain FSH and warranty cover?