Volvo RWD 700 Forum

After 13 months and too much money to count I've managed to bring a volvo back from beyond the grave. Now currently my problem is rather simple, I have an aftermarket boost/vac gauge. Naturally it reads in HG on one side and psi on the other. Now here's where it gets interesting. I've hooked this gauge up to the vac under the dash that runs to the factory boost gauge via an inline Tee. The gauge shows 20 Hg on start up and idle, applying the gas pedal results in the gauge dropping to 0 but never going into the boost side (of the gauge). Meanwhile the factory gauge acts like normal. I gather the factory boost gauge is vac operated?!

Anyway so I moved the gauge to an intake manifold vac line, can't recall which one but the gauge was the same result. So finally I cut into the wastegate actuator vac line. This time nothing, gauge just stayed at zero at any rpm.

So just how in sam hell do I get an aftermarket boost/vac gauge to register boost.

P.S
The turbo is in great shape, no leaks, wastegate and air by pass valve hold vac and work properly. and no vac leaks on the engine (I replaced every vac line I could find yesterday.()
HELP!