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Should A Boost Gauge Read Zero When Not Connected

Howie

By Howie,
in Engines & Forced Induction

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Howie Grand Master

Howie

Posted
Posted

Hey guys,

Just a quick question.. i've got a greddy boost gauge that i suspect might have a fault. but i'm not too sure...

so my question is , should a boost gauge read zero when not it is not connected to anything at all. mine's currently sitting at 0.5 bar. yet when it is connected up, and idling it sits on zero - however the readings appear to be far too high (around 0.9bar when it should be 0.5-0.6bar).

any ideas?

cheers

Howie

white33gtst Contributor

white33gtst

Posted
Posted

when a boost guage isn't connected to anything at all it should read 0. obviously because there is no pressure going into it so there is nothing to read.

when idling, the guage should sit at bout -0.5 bar i think it is, or just below it. if it is sitting at 0 when the car is on and idling, then yes there is something wrong there

TurboX Mentor

TurboX

Posted
Posted
  white33gtst said:
when a boost guage isn't connected to anything at all it should read 0. obviously because there is no pressure going into it so there is nothing to read.

when idling, the guage should sit at bout -0.5 bar i think it is, or just below it. if it is sitting at 0 when the car is on and idling, then yes there is something wrong there

???

On idle you have manifold VACUUM.

If you Boost gauge starts its numbers at 0 then it should read 0 at idle!

If your gauge starts at - something it should read the idle vacuum, mine says about -20PSI (Mazda Familiar GTX)

Rev slightly and it goes from -20 to 0 then on to whatever boost I make when reving past 2000.

Howie Grand Master

Howie

Posted
  • Author
Posted

Thanks mate,

Well this is the model of the boost gauge in question. Guessing it should be a quarter way down from where it is there on idle and zero when not connected.

post-950-1159333865.jpg

TurboX Mentor

TurboX

Posted
Posted

The pic shows where it would be with maybe 2000rpm or not connected.

It should be down much lower at idle but not sure at what number on your car.

fr0st Experienced

fr0st

Posted
Posted

I got the exact same gauge. It sits on 500mm (ie down the bottom) at idle.

You should have a little white box it connects to which should have a little knob (or equiv) you can adjust it with, either that or its on the back of the gauge. I didn't install mine so I'm not sure exactly where it is

Howie Grand Master

Howie

Posted
  • Author
Posted

Thanks heaps guys. Just having a chat to satanic just then, and he's theory seems to fit in best, the face plate may have rotated when i put the gauge in the a-pillar (it was a bitch to fit in and i was grabbing and twisting the hell out of the thing).

I'll check it out again tonight. Cheers again guys most helpful bunch over at sau.

RB SANDY Rising Star

RB SANDY

Posted
Posted

Hi a mate had a autometer boost gauge and it showed 2 psi up, but in the instructions It tells you to undo a screw to set in back to 0 they do this because to the pressure when transport e.g., plane and the difference in other countries.

hanyou Grand Master

hanyou

Posted
Posted

interesting... my mech oil temp gauge sits at 60degrees unless it gets hotter.. so let me know how u fixed it so i can adjust mine also >_<

also my water temp doesnt work at all :O and YES i connected it up properly lol

siddr20 Grand Master

siddr20

Posted
Posted
  Quote
however the readings appear to be far too high (around 0.9bar when it should be 0.5-0.6bar).

got full exhaust??

If so, then the boost will increase slightly..

Got boost controller of any sort?? Then maybe it has been boosted..

Beer Baron Grand Master

Beer Baron

Posted
Posted

first things first. is it a mechanical guage or electric? ie. does it run a vacuum line to the back of the gauge?

if it's mechanical it should read "0" when car is switched off, or gauge is not connected. if it's electric it should just fall to the 6 oclock position.

the mechanical gauges have a bourbon tube in them, these can get damage and it tends to happen when they have been removed/replaced. was the guage new or second hand? the face does not rotate so it would not have moved during your installation into the a pillar. sadly if it is damaged it's most likely a throw away.

Howie Grand Master

Howie

Posted
  • Author
Posted

Gidday guys,

Yep it's a mechanical - has a turbo/split dump pipe, but the restriction's in the rest of the system. No boost controller, so no way it'd be running 0.9bar.

I think i'll have to adjust it like you say.

let you know how i go.

Munkyb0y Grand Master

Munkyb0y

Posted
Posted

i have a spare mech boost guage (splitfire) that was reading -10 when disconnected.

i pulled it apart, not easy as it was not meant to be opened, and there's a weight on a coiled spring that moves thru pressure entering the nipple.

if you can get it open, move that weight around slightly with ur finger, and you will see the needle sitting at different spots. once u get it to zero, it should be good to go.

Howie Grand Master

Howie

Posted
  • Author
Posted

Just having a look, this ain't gonna be easy to open. I'll need some sort of special tool to take the special bolts off at the end of each of those threads. But i'll see if i can do it with a few mobile phone toolsets.

post-950-1159346789.jpg

Thanks again.

Munkyb0y Grand Master

Munkyb0y

Posted
Posted

is there anyway you can take the glass/rim off the front? that's how i did mine.

taking those bolts out wont help, not on mine anyway.

i bent the bezel lip slightly and slipped the rim off. then undo that bolt around the nipple(where the hose goes), and the face comes out in one piece.

I didnt really care if i broke it or not, coz it was a spare, but it works now.

keep in mind, that's how mine opened/worked. i'm not familiar with yours, i'm just assuming that they all work the same.

Howie Grand Master

Howie

Posted
  • Author
Posted (edited)

I started taking it out from the front, then scratched it and thought to myself I really should exhaust all other options first. Anyhow it'll probably be binned or relegated to a playstation cabinet if it's not fixed.

Edit : Thinking about it logically, it must be assembled from the front in the factory, so naturally you'd think it'd come out from the front also.

Edited by Howie
Munkyb0y Grand Master

Munkyb0y

Posted
Posted (edited)

Na, it's no trouble. Have done it several times now.

Got pics for you here with some explanations.

If you can find another way, or other advice, try it. Coz you will damage the bezel getting it off, but try keep the damage to the back so you dont see it.

Ignore the duct tape in the first pic, that's just to hold it in it's cup tightly, not a result from taking it apart, lol.

post-29392-1159351889.jpg

post-29392-1159351900.jpg

post-29392-1159351909.jpg

post-29392-1159351919.jpg

post-29392-1159351926.jpg

Edited by Munkyb0y

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