Hooking up Full Sweep Boost Guage?

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Dave, I have an Autometer Full sweep gauge ( stepper motor type) I'm installing in my 06' with KW supercharger.It says to hook up to ignition on power but requires that the guage be powered up during startup in order to calibrate.It mentions that many ignition on power sources do not have power during startup as your radio is an example.I saw your post showing the power sources in the fuse box which is perfect ( lights ,ignition ) and really convenient. Will that give me power during start up?
My second question is where is the best place to hook up the vacuum line.I was thinking that since I am using a vented catch can and have the manifold port blocked off that would be a perfect spot. Thanks John

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Virtually all cars will have an interupt when the starter is cranked. This is to ensure that there is max power going into the cranking. The "hot with ignition" position on our fuse panel is still your best choice. You shouldn't worry about the short interupt in power. The gauge needs to see ZERO manifold pressure only briefly to calibrate itself. This can be done if you wait a couple seconds after you turn ignition to full ON before you hit the starter button. Even though there is a momentary power interupt, the gauge has already done the calibration just prior to the engine cranking. It will remember the last reading to "zero" itself. Try it, you'll see.
As for the vacuum source, that's exactly where I tapped mine. My boost gauge uses the port where the PCV valve used to go into the intake. You can use almost any of those hoses that run into the intake manifold. Some use the vacuum line from the fuel pressure regulator and just "T" into it. Those who left the PCV valve intact, just "T" into that. Those are all manifold vacuum/pressure sources.

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Virtually all cars will have an interupt when the starter is cranked. This is to ensure that there is max power going into the cranking. The "hot with ignition" position on our fuse panel is still your best choice. You shouldn't worry about the short interupt in power. The gauge needs to see ZERO manifold pressure only briefly to calibrate itself. This can be done if you wait a couple seconds after you turn ignition to full ON before you hit the starter button. Even though there is a momentary power interupt, the gauge has already done the calibration just prior to the engine cranking. It will remember the last reading to "zero" itself. Try it, you'll see.
As for the vacuum source, that's exactly where I tapped mine. My boost gauge uses the port where the PCV valve used to go into the intake. You can use almost any of those hoses that run into the intake manifold. Some use the vacuum line from the fuel pressure regulator and just "T" into it. Those who left the PCV valve intact, just "T" into that. Those are all manifold vacuum/pressure sources.

The instructions say "If the boost gauge is connected to a circuit that breaks the electrical connection during starting the auto zero function will not work properly and an inaccurate reading will result.The connection can be tested by turning the key switch from off to on,the pointer will move backwards to the stop pin and then move to zero.Once the pointer moves to zero,start the engine.If the pointer reads vacuum without returning to the stop pin,a suitable connection has been found.I f the pointer moves to the stop pin and then reads vacuum,another power circuit must be found". It appears that by breaking the connection during start up and the reintroducing power once you have started the car the gauge is unable to calibrate due to a slight vacuum.Is there any other spot you know of where I can connect to a power start hot?

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Here is a link to the gauge I 'm using. http://www.autometer.com/cat_gaugedetail.aspx?ref=search&gid=2638
I neglected to tell you it was a vacuum/boost gauge and not just a boost gauge.

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I think most boost gauges give this indication in the intruction sheet. Try it and see what happens. My AEM boost gauge says something very similar and it works just fine. You won't know till you try. It's a simple connection and if you use the female 1/4" spade connector, it's easy to disconnect and move it somewhere else.
The radio is on a circuit that was designed to shut down completely during cranking. The "hot with ignition" doesn't completely shut down but rather, it allows current to be diverted away from it, leaving a small amount of power still present. That is usually enough to keep the calibration.
One power source that is not affected by the starter is the "hot all the time" and if you use this one, you would have to install a switch so you can turn the power on and off whenever you want. Nobody does this. This source is just like if you connected it directly to the battery. Another source might be the one that Vortech uses to power the aftercooler water pump and that is located at a relay in the fuse box under the hood.
See figure 12g and 12f on page 28 of the Vortech manual:
http://www.vortechsuperchargers.com/pdf/manuals/4HS218im.pdf

I wouldn't mess with any of these other choices till you know for sure that the one at the fuse panel isn't working for you.

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Correction:

My boost gauge is also an Autometer, Sport Comp. series. It utilizes a MAP sensor for the vacuum/pressure interpolation.

http://www.autometer.com/cat_gaugedetail.aspx?ref=search&gid=2818

As you can see from my installation manual, it also states to use a power source without interuption. I use the "hot with ignition" power tap and have never had a problem with it.

(My AEM is the A/F gauge.)

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Correction:

My boost gauge is also an Autometer, Sport Comp. series. It utilizes a MAP sensor for the vacuum/pressure interpolation.

http://www.autometer.com/cat_gaugedetail.aspx?ref=search&gid=2818

As you can see from my installation manual, it also states to use a power source without interuption. I use the "hot with ignition" power tap and have never had a problem with it.

(My AEM is the A/F gauge.)

Ah,I see.You have the same gauge as me in a different series mine is a phantom version. I will take your advice and hook it up there.I did find one spot I tested.I hit the auto down on my driver window when I started the car and it still continued down when starting.I have no idea how or where to tap into that so I will try your power tap.Obviously if it works and you have the same gauge its the right place. Thanks Dave