# BOOST GAUGE NO WORKING - SUPERCHARGER



## dreww (Sep 28, 2006)

Ok, this isnt for my sentra, its for my buick riviera.

I have a stock SC on it, and tried to hook up a autometer boost gauge and its not working. Any ideas why? I tried various vacuum ports and none of them show boost under heavy throttling. I hear no line leaks and have plenty of power when getting on the gas. 

Think its the gauge, despite it being brand new? You can feel vacuum on the line when unplugged from the gauge, but I cant really drive around testing for boost with the line unplugged.


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## wes (Apr 30, 2002)

dreww said:


> Ok, this isnt for my sentra, its for my buick riviera.
> 
> I have a stock SC on it, and tried to hook up a autometer boost gauge and its not working. Any ideas why? I tried various vacuum ports and none of them show boost under heavy throttling. I hear no line leaks and have plenty of power when getting on the gas.
> 
> Think its the gauge, despite it being brand new? You can feel vacuum on the line when unplugged from the gauge, but I cant really drive around testing for boost with the line unplugged.


The boost gauge needs to be AFTER the supercharger. Are you sure the vacuum ports are after the SC? It is a roots type blower right?


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## dreww (Sep 28, 2006)

wes said:


> The boost gauge needs to be AFTER the supercharger. Are you sure the vacuum ports are after the SC? It is a roots type blower right?


yes, sorry i didnt specify. It is the root type blower.

there is an aux port on top i tried(near the intake-right of engine bay). easy and obvious...but not the answer. then i found a somewhat hidden port under the spout of the supercharger (left side w/ all the pulleys) with a vacuum line that runs behind towards the firewall with a t-connector and a plug. I pulled the plug and tried that line and it feels like all vacuum as well. Again.no boost on the gauge. the gauge is a boost only gauge.

is it possible there is no "boost port" on this SC?


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## wes (Apr 30, 2002)

dreww said:


> yes, sorry i didnt specify. It is the root type blower.
> 
> there is an aux port on top i tried(near the intake-right of engine bay). easy and obvious...but not the answer. then i found a somewhat hidden port under the spout of the supercharger (left side w/ all the pulleys) with a vacuum line that runs behind towards the firewall with a t-connector and a plug. I pulled the plug and tried that line and it feels like all vacuum as well. Again.no boost on the gauge. the gauge is a boost only gauge.
> 
> is it possible there is no "boost port" on this SC?


Does it not have an electronic gauge like the Pontiac cars do? I remember driving a GTP grand prix and that had the 3800 SC motor and it had an electronic bost gauge...

Perhaps try a forum dedicated to those cars?


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## dreww (Sep 28, 2006)

wes said:


> Does it not have an electronic gauge like the Pontiac cars do? I remember driving a GTP grand prix and that had the 3800 SC motor and it had an electronic bost gauge...
> 
> Perhaps try a forum dedicated to those cars?



thanks for replying wes.
No, the car does not have a stock gauge at all. I cant find other boards cause this car model (yrs 95-99) was kinda rare and not many modify it (aren't many options anyways).

this gauge is mechanical. should i try an electric one? I dont know if i have a MAP sensor to tie into for an electrical. Should I try t-connecting into the fuel pressure regulator vacuum line? maybe that will give boost?


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## wes (Apr 30, 2002)

dreww said:


> thanks for replying wes.
> No, the car does not have a stock gauge at all. I cant find other boards cause this car model (yrs 95-99) was kinda rare and not many modify it (aren't many options anyways).
> 
> this gauge is mechanical. should i try an electric one? I dont know if i have a MAP sensor to tie into for an electrical. Should I try t-connecting into the fuel pressure regulator vacuum line? maybe that will give boost?


The motor is similar to the one in the Grand Prix, I would suspect you could find someone on those forums to give you better answers. Ideally the FPR should see manifold pressures, but I am guessing as I do not know the layout of the SC and IM on that car...


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## dreww (Sep 28, 2006)

wes said:


> The motor is similar to the one in the Grand Prix, I would suspect you could find someone on those forums to give you better answers. Ideally the FPR should see manifold pressures, but I am guessing as I do not know the layout of the SC and IM on that car...



ok, I tied into the FRP line and finally got some boost showing on the gauge under heavy throttling (6+lbs)....until I went to work and it doesnt work anymore. I think its now a kink in the line or the fitting on the back of the gauge is too tight. I will look at it again when I get home.

thx for your help.


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