If this "Cap" was split.....

[Jehu]

Cap is #8 on the PCV/Intake Cover at the back of the IM. This is a rubber cap like a thimble of sorts that covers a pipe. What is the purpose of that Pipe? What would be the effect of that pipe not being sealed by the Cap due to it having split open? Would the Car drive with noticeably more "pick-up" after sealing that cap properly ( Electrical Tape)?

[Ferret]

Cap 8 covers the port that's supposed to go to the brake servo on an E38 740 - except on a 540 there's not space for one as it's all hydraulic. (Unless you've got a remote, then it'll probably take the feed from elsewhere up the front of the manifold.)

The car will run lean and misfire if that's leaking - so if you seal it up you should notice smoother running. If it was severe enough to cause the ECU to flip, sealing it will increase performance too.

[Jehu]

Cap 8 covers the port that's supposed to go to the brake servo on an E38 740 - except on a 540 there's not space for one as it's all hydraulic. (Unless you've got a remote, then it'll probably take the feed from elsewhere up the front of the manifold.)

The car will run lean and misfire if that's leaking - so if you seal it up you should notice smoother running. If it was severe enough to cause the ECU to flip, sealing it will increase performance too.

Great. Then I wasn't imagining the improved response I thought I was feeling.

Let me also ask on the bigger Pipe where you see the '3' pointing at the PCV valve (in the other pic above), should I ever see some oily residue coming out of that? If I do ,is it probably gasoline laking back in from the fuel rail down that little hose #6? What should be done if this is a malfucntion? Replace the PCV? Pressure regulator? Thanks an aweful lot for the reply.

[Ferret]

#3 in the first image is the crankcase breather, which a load of exhaust gas, oil vapour and general nastiness flows through. If it's leaking crap everywhere the O-ring (#4) inside is probably shot at.

If that O ring is shot at, it's probably time to do the whole PCV plate as the diaphragm is likely in as bad a condition.

On the second image #6 is the vaccuum hose connected to the fuel pressure regulator on the end of the fuel rail, it's not a fuel line. I'd be very worried if that started piddling fuel everywhere.

[Jehu]

#3 in the first image is the crankcase breather, which a load of exhaust gas, oil vapour and general nastiness flows through. If it's leaking crap everywhere the O-ring (#4) inside is probably shot at.

If that O ring is shot at, it's probably time to do the whole PCV plate as the diaphragm is likely in as bad a condition.

On the second image #6 is the vaccuum hose connected to the fuel pressure regulator on the end of the fuel rail, it's not a fuel line. I'd be very worried if that started piddling fuel everywhere.

OK . The residue isn't "everywhere' its just evident some discharge is escaping so if I'm not supposed to see any fluid residue externally I'll get that done.. thanks for the insight.. I'll probably have the shop swap that PCV when i bring it in for the Timing Chain Cover Gasket /Power Steering Hose job.