V10 SAI and vacuum system check valves

A6 All/ S6 All
#1

So my question is simple. The hose coming off the front of the IM, is this solely for the SAI system? I ask because the rear of the IM / upper Y intake vacuum inlet goes directly to the suction jet pump for the brake assist? - my assumption

Is the vacuum port in the front even needed if you dont have the sai system on the car?! It is labeled as emissions: AUDI OEM 07-11 S6 5.2L-V10 Emission-Check Valve 058905291K

s-l400

My objective is to remove un-needed vacuum systems in attempts to narrow down why my vacuum pump still running all the time while braking as if there is not enough vacuum stored in the vacuum system

From the vacuum routing there is a small secondary vacuum reservoir on the drivers side of the car under the fender and a set of bluebells vacuum resevoir on the passanger side connected by a hard line that spans the front of the engine.

Do we need the blue balls for brake assist?

I am wondering if vacuum stored in the blue balls travels through the front IM to the rear upon throttle lift and used for the brake assist, etc…

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#2

Ok, I will answer my own questions from some details I learned by talking to my audi tech friend and some deduction. So the front port on the IM supplies vacuum to the reservoir thru the check valve to maintain vacuum on the evap purge in the fuel tank during evap testing for leak and the purge valve is closed and not venting fuel vapors into the rear of the IM. Then when opened, the evap purges vapors into the IM.

In addition the front vacuum of the IM would traditionally supply the SAI valve, kombi valves,
as well the changeover valves in the older audis with vacuum change over IM valves.

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The vacuum reservoirs, blue balls and small black reservoir, are on the side of the check valve that would not allow vacuum to vent back into the IM and into the brake booster system, so in turn the reservoirs do not assist in any manner to supply any brake booster vacuum.

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With my car, given no SAI valves to actuate. The vacuum stored in the blue resevoir is on the downstream side of the checkvalve therefore has a constant vacuum on the evap. This must maintain in tact. However, I see the small black reservoir is tapped directly to the IM where the junction to the sai solenoid used to be and in turn I see no need for this vacuum line.

In turn I am wondering if both check valves are truly necessary. I am receiving a baffling effect on the IM check valve so will defiantly replace. The black T fitting check valve is on to the hard lines so will not replace. Never had any evap codes so assume working properly.

#3

Great work and great update. What a pain.

#4

Saved me so much time. THX MAN!