2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.
View Poll Results: Vacuum reading at idle when warm
16- inHg
9
33.33%
17 inHg
5
18.52%
18 inHg
5
18.52%
19+ inHg
4
14.81%
16- inHg (ported)
1
3.70%
17 inHg (ported)
1
3.70%
18 inHg (ported)
0
0%
19+ inHg (ported)
2
7.41%
Voters: 27. You may not vote on this poll

Vacuum reading at idle

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Old Jul 29, 2003 | 10:52 AM
  #1  
Fingers's Avatar
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Vacuum reading at idle

What vacuum reading do you get at idle (please post only if measured with aftermarket gauge)?
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Old Jul 29, 2003 | 11:30 AM
  #2  
RoninAutoBoX's Avatar
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I was told that my engine has 12 inches of vacuum at idle. I don't see that option above, so I am starting to get worried.
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Old Jul 29, 2003 | 11:54 AM
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mine is like 230-260mmhg
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Old Jul 29, 2003 | 12:24 PM
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is there somewhere specific you should plug in a aftermarket gauge?
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Old Jul 29, 2003 | 12:31 PM
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Shouldn't those numbers be negative?

-20 isn't on the poll.
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Old Jul 29, 2003 | 12:36 PM
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Nope :P what happens if you get negative vacuum reading?

Now if i would have said boost reading, then yes, they should be negative. I knew you'd scrutinize this so i plotted my retort in advance

Score: Fingers - 1, Aaron - 0
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Old Jul 29, 2003 | 12:36 PM
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I get -16 vaccum at idle on huge street port
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Old Jul 29, 2003 | 12:40 PM
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***I was told that my engine has 12 inches of vacuum at idle. I don't see that option above, so I am starting to get worried. ****

Aw shucks, stop worrying. There's not a darn thing wrong with those figures. Geeez whizzz.
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Old Jul 29, 2003 | 12:41 PM
  #9  
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From: London, Ontario, Canada
True.
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Old Jul 29, 2003 | 12:45 PM
  #10  
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what's the conversion from bar to inHg or -psi to inHg?
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Old Jul 29, 2003 | 12:54 PM
  #11  
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From: Ottawa, Ontario
No such thing as -psi. It's either mmhg or inhg,

1inhg=25.4mmhg
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Old Jul 29, 2003 | 12:57 PM
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From: Kicking down doors in a neighborhood near you
for bar to psi, 1 bar= 14.7psi
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Old Jul 29, 2003 | 01:00 PM
  #13  
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From: Iowa
hehehe just like in life there isn't such a thing as -2 or 2i

well i think my guage reads kpa (damn pascals.....) wich is a bar me think.

my old engine use to run -50 and my new one runs -40
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Old Jul 29, 2003 | 01:27 PM
  #14  
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From: South Florida
I'm sorry! It's just that I have always felt confident with my 12 inches, and then I see this poll and people whipping out 16-20 inches and suddenly I'm not feeling very large and in charge anymore!
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Old Jul 29, 2003 | 01:30 PM
  #15  
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From: Canada
here's some help so ppl can convert their numbers to the standard that fingers is using:http://www.onlineconversion.com/
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Old Jul 29, 2003 | 01:32 PM
  #16  
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From: NW Arkansas
wouldn't negative vaccuum be pressure? so the 20in of vaccuum is a valid answer

and in case you cant read, negative 12 would go under the - (should have been < ) 16 and 20 would go under the +19 (once again should have been > )
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Old Jul 29, 2003 | 01:53 PM
  #17  
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From: Kicking down doors in a neighborhood near you
vaccuum is the lack of pressure. Negative vaccuum would be positive pressure, a.k.a. boost
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Old Jul 29, 2003 | 01:57 PM
  #18  
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From: Iowa
me think it's a vector..........(can be)

magnitude and direction

so my 2 cents are da negitive numbers too

just like if i was standing on a box i be putt'n 1g down (positive)......but if the cat jumped out of the box pushing me up in da air (negitive g) and of course no force in either direction would be zero g's (not positive or negitive)

i aint no fysics major but if a rock goes up it comes down and hits me too. Damn vectors can hurt..............

btw that site is nice thnx
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Old Jul 30, 2003 | 12:11 PM
  #19  
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From: West Bloomfield, MI
60 kPa
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Old Jul 30, 2003 | 02:35 PM
  #20  
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From: Iowa
damn.....that's pretty strong. What do you have for engine internals?

is that at 750rpm?

i though i was doing good getting 50kpa on my olde engine
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Old Jul 30, 2003 | 03:54 PM
  #21  
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From: West Bloomfield, MI
Stock S4 TII engine, history unknown. The cluster reads 130K, but I can tell by the way the engine harness sits that someone has been in there.

I have removed everything that is unecessary for the car to run except P/S.

The idle is perfect at 750, but with the stock BOV routed back into the TID, it pulled near 70 vac. The Blitz SS BOV I have currently is being replaced with a HKS SSQV as soon as I get the flange welded onto a pipe.
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Old Jul 30, 2003 | 04:06 PM
  #22  
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From: Iowa
holy ****.................nice

i have a s4 TII everything removed and i just rebuilt the motor and it has 3.5k on it and it's only pull'n 40kpa.

the pineapple motor in it before with only 13k only pulled 50kpa.

grrrr.............i guess it really doesn't matter as long as it runs
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Old Jul 31, 2003 | 01:10 AM
  #23  
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From: Bay area
my street port NA shows ~20inHg at idle ~1000rpm. This is viewed in the E6K dos software, reading from the MAP sensor.
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Old Aug 15, 2003 | 06:34 PM
  #24  
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From: Arkham Asylum
46 kpa @750rpm with a huge streetport...
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Old Aug 22, 2003 | 03:02 PM
  #25  
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From: FWTX
With a totally stock TII with 140,000 miles I was around 450mmHg at idle.

I changed my air filter to a K&N drop in replacement, and it's now at 250-300mmHg!
Is this good or bad? It was idle normally, and ran fine.
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