boost guage- y vaccum reading? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

autobahNESSA · 11-12-2003, 07:57 PM

Just curious, why does the boost guage have a vaccum reading?
Mine is hooked up through the wastegate line and all I see is boost. -which I expect.
But then how come the boost guage has vaccum and boost combined on it? Its an auto meter.

In order for it to read vaccum would it have to be hooked directly into the manifold? I think at idle inside the manifold it might read a vaccum but I'm not sure.

Can someone give some insight thanks.

Evil S14 · 11-12-2003, 08:34 PM

the vacuum gauge has to be conncted to the manifold to read vacuum, the only reason i can think of it is to see if you have a vacuum leak. If you suddenly get a leak then the gauge will pull less mercury than it should

any one else care to elaborate?

teg · 11-12-2003, 10:39 PM

The reason it has a vacuum reading is regardless of the fact that it has a turbo, an engine still makes vacuum when not under boost. Manifold vacuum is a great way to find problems with the engine. Like fluttering needle, high vacuum, low vacuum, etc... which can help find vacuum leaks, burned valves, head gasket problems....

you should have your boost gauge connected to the intake manifold.

the head · 11-13-2003, 12:04 PM

T the boost gauge off the FPR line on an SR to see full range

groozdas · 02-01-2004, 06:48 AM

Quote:

Originally Posted by the head

T the boost gauge off the FPR line on an SR to see full range

what is FPR line? sorry for a stupid question..

G

rrobe99999 · 02-02-2004, 07:27 AM

fuel presure regulator. A lot of search results will give you this answer, but a friend showed me a better way on my car. Just under the spot were the cold pipe connects to the throttle body, there are three nipples for vacuum lines. One of these was capped off, so I hooked it up there. No spliceing needed.

11-12-2003, 07:57 PM	#1
autobahNESSA Zilvia FREAK! Join Date: Aug 2002 Location: Milpitas/Irvine, CA Posts: 1,257 Trader Rating: (3) Feedback Score: 3 reviews	boost guage- y vaccum reading? Just curious, why does the boost guage have a vaccum reading? Mine is hooked up through the wastegate line and all I see is boost. -which I expect. But then how come the boost guage has vaccum and boost combined on it? Its an auto meter. In order for it to read vaccum would it have to be hooked directly into the manifold? I think at idle inside the manifold it might read a vaccum but I'm not sure. Can someone give some insight thanks.

11-12-2003, 08:34 PM	#2
Evil S14 Zilvia Addict Join Date: Dec 2001 Location: Indianapolis/Bloomington Age: 41 Posts: 610 Trader Rating: (0) Feedback Score: 0 reviews	the vacuum gauge has to be conncted to the manifold to read vacuum, the only reason i can think of it is to see if you have a vacuum leak. If you suddenly get a leak then the gauge will pull less mercury than it should any one else care to elaborate? __________________ image exceeds forum limit -Moderation

11-13-2003, 12:04 PM	#4
the head Nissanaholic! Join Date: Jul 2002 Location: in a dark room mastering the art of typing with one hand Posts: 2,164 Trader Rating: (3) Feedback Score: 3 reviews	T the boost gauge off the FPR line on an SR to see full range __________________ I never knew you could do that with an eggplant

11-12-2003, 10:39 PM	#3
teg Join Date: Nov 2003 Location: chicago Age: 43 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	The reason it has a vacuum reading is regardless of the fact that it has a turbo, an engine still makes vacuum when not under boost. Manifold vacuum is a great way to find problems with the engine. Like fluttering needle, high vacuum, low vacuum, etc... which can help find vacuum leaks, burned valves, head gasket problems.... you should have your boost gauge connected to the intake manifold.

02-02-2004, 07:27 AM	#6
rrobe99999 Zilvia Member Join Date: Jul 2003 Location: Destin, Fl Posts: 262 Trader Rating: (0) Feedback Score: 0 reviews	fuel presure regulator. A lot of search results will give you this answer, but a friend showed me a better way on my car. Just under the spot were the cold pipe connects to the throttle body, there are three nipples for vacuum lines. One of these was capped off, so I hooked it up there. No spliceing needed.