Be aware If you are referring to those 4 lower stubs for those Oetiker ear clips on the pipes at the back of the inlet manifold they are coolant pipes, not vacuum pipesdouglas96 wrote: ↑Thu Oct 04, 2018 5:35 pmAt the rear of the upper intake manifold are several vacuum hoses that connect to it. Hopefully one has popped off. If it has you may need to remove the bolts for the upper manifold to be able to move it slightly to get access to crimp the Oetiker ear clips on the hose(s).
Ahh, thanks for the correction! I just assumed (obviously wrongly) when I was taking my inlet manifold off that they were all vacuum hoses. I had already drained the coolant as per the procedure so the hoses were empty - had I not drained it beforehand, I would have realised pretty quickly!ATinOf wrote: ↑Thu Oct 04, 2018 8:59 pmBe aware If you are referring to those 4 lower stubs for those Oetiker ear clips on the pipes at the back of the inlet manifold they are coolant pipes, not vacuum pipesdouglas96 wrote: ↑Thu Oct 04, 2018 5:35 pmAt the rear of the upper intake manifold are several vacuum hoses that connect to it. Hopefully one has popped off. If it has you may need to remove the bolts for the upper manifold to be able to move it slightly to get access to crimp the Oetiker ear clips on the hose(s).
https://audi.7zap.com/en/rdw/audi+rs6+r ... 121024/#33
Only the odd one at the top on one side is vacuum; if your brakes work fine its unlikely its this as it goes to your brake servo.
I would say hissing creating suspects under that cover or in that vacinity could be; the vacuum suction line from the vac pump; the secondary air pipes(unlikely I would say); the PCV link pipe
The hissing is unlikely to be your N75 valves which are next to your turbos, but your loss of boost may be related to these or their vac lines (you could have more than one issue!)
https://audi.7zap.com/en/rdw/audi+rs6+r ... -145010/#3
Assuming you have checked your charge tube clamps all round (that was what my trouble was here; viewtopic.php?f=47&t=129234)
I would check your MAF sensors (Charge Pressure Senders) havent broken their seal at your charge tubes
Maybe its normal then, I just hadn't noticed it before now, but then hadn't had the engine running with the bonnet up.Stiggles wrote: ↑Thu Oct 04, 2018 6:59 pmI've also got a hiss from underneath the RS6 cover, when removed you can tell it's directly below. Without having anything to compare against I have been assuming it was a characteristic of the car as opposed to a fault, although it may be possible something was nicked or not replaced when Audi did my engine drop.
You were given the link for the N75 valve - its part ref 3 in the above
No problem, but don't thank me - thank IanH755 who is kind enough to host the English version of the study guide for us all to see.Toady1 wrote: ↑Fri Oct 05, 2018 8:22 amDouglas96 thanks for the study guide!
If the charge pipes had split or popped partially off I'd have thought the boost leaking would be audiable and quite obvious. I can't hear any boost leak, only the hissing from the rear of the engine near the top. I found a small split hose going to the rhs air box lid last night, but it wasn't that as I've replaced it with a piece of silicone hose I had.
I plugged it into Vagcom yesterday and the actual boost was half the demand boost on the graph. It didn't come up with any dtc's either, I'd have thought if the N75 valve was gone it would pick up a fault on the VCDS.
Looks like I'll be busting the jack out this weekend for a look under the car, see if I can see anything....
Good effort! I checked mine out whilst I worked on my car last weekend and they looked ok, though I didn't pull back the wheel arch liner to fully inspect, this is how they looked....
