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Discussion Starter #1
I need help understanding my boost gauge. This is my first car that has had a turbo. I got it used from a dealership so I had no way of contacting the previous owner. I have color coded where I'm getting the readings for it. Below is a key. Any help would be great.

Red = where it sits when it is idling or there is no pedal applied
Yellow = where it sits during normal driving (i.e. when the cruise control is set)
Green = where it is during spirited acceleration

Where the needle is sitting in the photo is where it is at when the car is off, just to clarify.

If anyone has any other questions let me know. Sorry if the photo is big, I wanted yall to be able to see it clearly.

 

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Captain James of the SS Impreza has gone down with
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Discussion Starter #3
Thanks. That definitely helps
 

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MPa is just another unit of measure for pressure. .15 MPa is about equal to 22 PSI. You have maximum vacuum at idle - the turbo isn't forcing air into the engine, it is sucking in the air it needs. Cruising is a similar situation, not a lot of load on the motor so you're not in boost. During acceleration, high load so high boost. Everything looks normal.

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Captain James of the SS Impreza has gone down with
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Your car reads in MPa, rather than PSI/inHg like many other gauges...

Green is ~13psi, which is good for a stock car.

Yellow is ~15inHg, which is normal. It likely fluctuates.

Red is ~20-25inHg, which is typical.

Only thing really "off" is that it isn't zeroed-out when off...

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It should be at 0 when its completely off...for me it was when I had that gauge.

The idle part seems ok

Is that your max boost you're hitting?

It makes life so much easier to not convert MPa to PSI...let me know and I'll hook you up on a deal for a boost gauge and maybe an ATi cluster holder like mine.

 

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Discussion Starter #8
Yes that is that max boost I am hitting. I was wondering about it not sitting at 0 when it was off. I might hit you up on that Kronos
 

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Discussion Starter #10
Cool. Is there any particular gauge that you recommend? Will it require any new sensors or can I just replace the gauge?
 

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Cool. Is there any particular gauge that you recommend? Will it require any new sensors or can I just replace the gauge?
You may either need to run a new vacuum line or find an adapter that connects to the back of the boost gauge. Its nothing extremely hard but just something to be aware of if you get the same one I got.

Here is my setup:

ATi 02-06 WRX/STi 52mm Steering Column ePod ATi 02-06 WRX/STi 52mm Steering Column ePod [ATI-25EJ2-EPOD-52] - $94.99 : Kronos Performance, Leading since 6th Century BC

Autometer Ultra-Lite 52mm 35 PSI Mechanical Boost Gauge [4304] - $65.60 : Kronos Performance, Leading since 6th Century BC

If you decide to go with it, PM me and I'll give you a free shipping coupon.
 

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Friendly Neighborhood Spider-Admin
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My stock boost gauge doesn't zero out as it should, either. I see the same points during driving, except for full boost. My turbo/tune situation is probably a little different from yours.
 

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Only thing really "off" is that it isn't zeroed-out when off...
The outside air pressure can vary quite a bit from day to day, and if that gauge is actually updating while the car is off (not sure if an "analog" gauge would), that could explain the difference....
 

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Friendly Neighborhood Spider-Admin
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Over the last 6 years, my stocker has fallen to the same incorrect point regardless of ambient pressure. The kinds of variation that you're talking about are quite tiny when compared to what the gauge is designed to measure.
 

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The gauge might have a zero adjustment on the back.
 

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Friendly Neighborhood Spider-Admin
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But then I would have to recalibrate my brain. :eek3:
 

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It makes life so much easier to not convert MPa to PSI...let me know and I'll hook you up on a deal for a boost gauge and maybe an ATi cluster holder like mine.
That's relative. I'd bet more people understand metric units than pounds or inches. The pascal is a derived SI unit, whereas the PSI makes little, if any, sense, so Subaru did the right thing in expressing pressure with the correct units (their MPH speedo is a concession to $ I think). The PSI is still widely used for tyre pressures and such but things would be tremendously simpler if things like the PSI, pounds, inches, and so on would be consistently expressed in SI or even everyday metric units.

I'd encourage the OP to increase use of SI units.
 

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Discussion Starter #18
Okay another noob question. I got my gauge and new cluster holder Monday and I plan on installing them today after work. Is it wise to unhook the battery when working with the lights for the gauge or will it be safe to not worry about unhooking it?
 

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Okay another noob question. I got my gauge and new cluster holder Monday and I plan on installing them today after work. Is it wise to unhook the battery when working with the lights for the gauge or will it be safe to not worry about unhooking it?
It will probably safe but it's always better to unhook the battery when doing any electrical work.
 
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