Need help with intake vacuum gauge reading from more cars

[logray]

If you have an early 986 or 996 (pre 2001), and you have a vacuum gauge, it would be great help to me and perhaps the community if you could take an intake vacuum gauge reading.

Basically, once the engine is up to temp and idling, you pull the intake hose off of the fuel pressure regulator and then connect it to your vacuum gauge.

When you take your reading, note if the needle is steady and how many inches of mercury it is reading. It would also be helpful to know what approximate elevation you took the reading at and outside temperature.

Thanks in advance if you are able to help.

I'm reading 16 inches of mercury at 56F outdoor temp and 2000 feet elevation.

I'm not sure the exact location of the pressure regulator on a 986, but it is probably on the drivers side fuel rail towards the front of the car on top of the engine. On a 996 the hose is dead simple to access and connect to your gauge. On the right hand side of the engine bay, reach around behind the power steering lines to the regulator on top of the fuel rail. There is a small vacuum hose there, you simply pull it off the fuel pressure regulator and connect it to your gauge. Here are a few pictures of how my gauge is attached. Literally takes me just a few seconds to disconnect form the fuel pressure regulator and to my gauge.

(click to enlarge)

[logray]

I took the car to near sea level and it read between 17 and 18 in hg.

[rallygabe]

99 c2

I read exactly 15"

cold idle, no fluctuation

I also suspect some leakage though have not been able to find it at this moment

[Ahsai]

99 c2I read exactly 15"cold idle, no fluctuation I also suspect some leakage though have not been able to find it at this moment

You need to measure it again when the engine is fully warmed up. When cold idling, the throttle butterfly is partially open letting more air in hence less vacuum.

[JFP in PA]

I took the car to near sea level and it read between 17 and 18 in hg.

We usually see 15-17 inches (varies from car to car) of vacuum (car warmed up) and we are a couple hundred feet above sea level.

[JasonStern]

Since I just did this...

Steady 14 in.Hg of vacuum

89'F ambient temperature

4800 feet elevation

engine at operating temperature

680 RPM idle

[valfam]

I will try to get you my reading this week.