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arent N/A's supposed to pull -760mmhg?

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Old 12-22-02, 09:05 PM
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arent N/A's supposed to pull -760mmhg?

I installed my boost gauge on my still NA, and when i turned the key over, the gauge didnt move. I know this is a stupid question, but isnt the gauge supposed to go down into the negatives because its pulling a vacuum?
Old 12-22-02, 09:19 PM
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my SAFC saids I pull -760mm/hg on decel and -560mm/hg in idle and full throttle

Last edited by pd_day; 12-22-02 at 09:28 PM.
Old 12-22-02, 09:26 PM
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so how come my gauge isnt changing..I installed it in line to the pressure sensor?
Old 12-22-02, 09:30 PM
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by turning the key over. you are starting the car?? or just turning to on??
Old 12-22-02, 09:33 PM
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must be talking about cranking it over....
Old 12-22-02, 09:33 PM
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sorry, my bad, i meant starting the car. I let it idle and gave it a tiny bit of gas, but it stays at 0.
Old 12-22-02, 09:35 PM
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why did u install a boost gauge on an n/a anyhow? why not just buy a vacuum gauge for like $40? or are you planning on swapping in the future?
Old 12-22-02, 09:37 PM
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I would recheck the hoses from the engine to the pressure sesnor and gauge.
Old 12-22-02, 09:38 PM
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im doing a TII swap next week
Old 12-22-02, 09:50 PM
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Sweet, have fun man, pm me if you have any questions.
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Old 12-22-02, 10:02 PM
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I would unhook the line and blow / suck on it while somebody looks at the gauge to see if it moves. maybe your line is kinked or broken to the gauge.
Old 12-22-02, 10:19 PM
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yup, i took the tube off the pressure sensor and blew into it, and the gauge went up, sucked in, went down..the hose tasted like gas and oil..yum
Old 12-22-02, 10:22 PM
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oh well, im not gonna worry about it now, it might just be something is clogged on the engine..as long as it works in a week.
Old 12-22-02, 10:53 PM
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how much do you suck?
Old 12-22-02, 11:33 PM
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hahah thats fucked up
Old 12-23-02, 01:58 AM
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you said you went inline with the stock sensor? don't do this. there are some unused nipples on the back right hand side of the motor ( in the car) just follow the vac lines from that thing on the back. connect your hose there it should work fine then
Old 12-29-02, 11:24 PM
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Re: arent N/A's supposed to pull -760mmhg?

Originally posted by darkwaveboi
arent N/A's supposed to pull -760mmhg?
760mmHg of vacuum is absolute zero pressure, and is physically impossible (whatever the some people's S-AFC's might say). Most engines (turbo or NA) idle at around 355-405mmHg (14-16inHg) vacuum and can go as low as 560mmHg (22inHg) on decelleration.

I presume you've tee'd into the pressure sensor? There's nothing wrong with doing this, but if you pulled the hose of the pressure sensor, blown into it and the gauge moved, but the running engine doesn't move it, then there's a blockage between the tee and the manifold. This is serious because it means the pressure sensor isn't getting a signal either, which is dangerous for your engine.
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