No vacuum

[John Ceta]

I was driving my parents' GN which is fresh out of the shop from an engine rebuild. It has an autometer boost gauge.

The car runs all right, but I noticed that the gauge never goes into vacuum. It will go into boost though, at the same time that the factory gauge does.

I'm guessing that there is a vacuum line to the gauge and that it isn't attached? Could it be something more serious?

 

[SHADOWII]

It may be...

the line that the boost gage is connected to has a check valve in it and it cannot register the vacuum. just take a look under the hood and follow the boost/vac. line to it's connection. If you find a black and white plastic piece between the connection and the manifold, that is the check valve.:smile:

 

[John Ceta]

Forgot about this thread.

I traced the tubing the other day and if I'm remembering right, first, it goes into a T-fitting. One tube coming out of the T is connected to a sensor, and the other continues on towards the turbo. The tube the continues on towards the turbo branches once more into two more tubes. One goes on to connect to one side of the turbo. I didn't see where the other one went to (was just taking a quick look) but I'm assuming it went into the other side of the turbo. Does this make sense? I'd take pictures, but I can't find the charger for my camera.

 

[SHADOWII]

If I....

understand you correctly, the line is going to the turbo/wastegate hose. This is not an accurate sampling of the actual boost/vacuum in the manifold. Use the map sensor line(preferred) or one of the other lines from the vacuum block.