Hoses to the intake plenum

5.0 V10 50v biturbo - 571 bhp
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Hoses to the intake plenum

Post by trj » Wed Mar 08, 2023 8:45 pm

Hello guys!

Have some strange hoses coming from each side of a solenoid, attached between the vacuumchamber and the intake plenum.
Both hoses are plugged at the other end, and due to drawings theese two hoses shouldn`t be there. This came with the car that
I purchased two years ago. Problems I have with the car at the moment are: The rpm meeter doesn´t work after start up, and at the same
time the startmotor do not shut of until after 10 sec. The signal to the relay stays on. This only appears when the engine is warm. NEVER cold.
The problem is also reduced in cold weather.
A more seldom problem is that efter starting the engine the engine lamp comes on, engine stumbles and missfires, and a high skwekee noise
is heard. The car runs like <beep>, but all is good after restarting. This only happened 3 times over two years.

What are the hoses for, can the problems I have be related to theese? If not, what are they for, and what can the problems I have be related to??

Thank`s for input!

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Re: Hoses to the intake plenum

Post by IanH755 » Fri Mar 10, 2023 6:30 pm

The hose in picture 1, 2, 3 & 4 is supposed to be directly fitted from the intake to the N249 solenoid, which controls both of the mechanical "blow off valves" fitted into the bottom of each air filter box, and definitely does not, from Audi, come with that metal T-Piece and the additional hose.

The two blocked off hoses in picture 5 also are not Audi fitted parts.

This is just a pure guess but I wonder if, for some reason, someone has tried adding those extra hoses for things like boost gauges etc as the ones connected to the N249 (at the front of the engine) only monitor the air pressure in the inlet/intake and someone might have tried to do the same at the back of the engine but found that they couldn't connect to anything back there so just capped them off.

In which case the hoses themselves could be causing all kinds of pressure issues, with any leaks causes things to open/close incorrectly and fool the ECU.

All of that is just a guess though.

***EDIT*** - Here's a picture of mine net to yours and mine is a single uncut hose. I'd definitely consider removing that T-Piece in your hose and finding where the other end goes to!

***OLD*** Daytona C5 RS6 Avant - MRC'd - 500HP & 820NM (PistonHeads Link).

***NEW*** Daytona C6 RS6 Avant - MRC'd - 955HP & 1200NM (PistonHeads Link)

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Re: Hoses to the intake plenum

Post by trj » Mon Mar 13, 2023 11:13 am

OK, thank`s very much Ian! Very kindly of you.
There are two T-connections. One before the solenoid, and one after. (bad pictures)
Both of theese hoses goes back to the engine torpedo wall, and are stucked with one screw
in each. So I know where they end. The question now is: am I going to get trouble if I take them

Jim Haseltine
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Re: Hoses to the intake plenum

Post by Jim Haseltine » Mon Mar 13, 2023 1:33 pm

No, you won't. Neither of those T-pieces are original fittings. Turbo cars (especially Audis) have issues if there are air leaks in the induction or breather pipes, I'd remove the T-pieces and fit replacement OE hoses - you might well find that your running problems disappear. I'd guess that the run-on starter and lack of RPM readings are connected, I'd start by taking a look at the RPM sensor and it's wiring.

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Re: Hoses to the intake plenum

Post by trj » Tue Mar 14, 2023 5:20 pm

Many thank`s to you Ian !!😊👍👍👍

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