Can someone with a 535i please check this?

[scott 4991]

I really need a reference here... I'm hoping someone can check the vacuum here on their 535i and let me know if this is correct - bottom of the page.

http://www.bmwe34.net/e34main/trouble/engine_diagnose.htm

At this point, my reading is 8in Hg, not 18 as shown. This will affect my performance as the air flow (vaccuum differential) is calibrated to the AFM, which is tied to the O2 sensor, which all goes into the on-board Computer. I do read 19in Hg at the manifold IF I BLOCK the hose going into the MAF - but this is not how it's shown (not blocked) in the above link.

Without a reference, I am shooting in the dark.

Thanks in advance.

sc

[clevertd]

M30 engines had an AFM

[scott 4991]

Change made. thanks

sc

[scott 4991]

This picture shows the airflow - as you all know I'm sure, the measurement point "A" for the vacuum reading, and my measurement point where I get 19"Hg IF I PLUG point A. This hose shown goes directly to the intake manifold, the bottom nipple under the manifold.

As point A goes to the outside world, via the air cleaner, and heads to the MAS / vaccum differential - there must be some vacuum differential at point A, thus I can't have 18"hg as shown in the web link in the above original post. This is why I am confused on this.

Thanks

sc

[Ross]

The photo looks like the gauge is connected to the crankcase vent, not right.
I'm pretty sure the fuel pressure regulator sees manifold vacuum which is what you want and is easy to get at.
A steady 19" is a good reading.

[scott 4991]

Thanks Ross, so IS THE LINK SHOWN WRONG? This is what I need to know. Please see the link in the 1st post here, and tell me if you think it's incorrect. I will check the vacuum at the Fuel Pressure regulator - but was not aware this is the case. I thought a fuel line! Live and learn..

sc

[Jeff in MN]

Thanks Ross, so IS THE LINK SHOWN WRONG? This is what I need to know. Please see the link in the 1st post here, and tell me if you think it's incorrect. I will check the vacuum at the Fuel Pressure regulator - but was not aware this is the case. I thought a fuel line! Live and learn..

sc

wrong. As mentioned, the best place to T in is at the vacuum side of the Fuel Pressure Regulator. FPR.

good luck

[Ross]

If you were able to attain 19" then you probably stumbled on manifold vacuum regardless of where the connection was.
Yes, I believe the link to be wrong unless I am missing something that connection is to the crankcase.

[scott 4991]

Thanks for the help. For sure the 19" was at the manifold, I know the hose goes directly under the intake manifold to the connection there. I appreciate you (Ross) looking at the link and commenting on this.

sc

[genphreak]

Thanks for the help. For sure the 19" was at the manifold, I know the hose goes directly under the intake manifold to the connection there. I appreciate you (Ross) looking at the link and commenting on this.

scI wonder how much difference (if any) the ambient pressure makes... (I don't think much, just a warning, JIC someone knows).