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Jphoenix13

Noisy vacuum pump

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My 95 S4 has an electric vacuum pump in the back of the engine bay (where the electronics are located on a pre-revised wiring car) - it is very noisy - is it normal for it to be so loud?

 

When I turn on the ignition, it drowns out the fuel pump and brake pump; just wondering if that's normal or it's showing signs of failing?

 

Thanks,

 

Jim

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It s encased in a foam block, but I dont think it stops running, I shall check. There are two connections, one with a hose, the other nipple has no hose, not connected to anything.

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Hiya.  The pumps are quite loud but should only run a few seconds at a time.  The connections are correct - one vents to atmosphere.  To check the pump is working properly, take off the hose and put your finger over it.  It should stop running within a few seconds.  If not, it's faulty.  If it does stop running when blocked by your finger, then you have a vacuum leak somewhere.  Trace the hose, disconnect and block at various points until the pump stops running, then you've found your leak.  Could be behind the dash though!

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Alternative answer is that if with your finger over the end as suggested it doesnt stop running, then it needs adjustment. Its a simple task..open the casing, youll see a little tiny connector attached to a threaded bolt that can be wound in and out to adjust its pressure for cut out..its been covered before but if u need any pics I can send them u as ill have my,head in the 'bay at the weekend

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OK, great info guys - the finger test reveals pump is working properly, so I start pinching off hoses with needle nose pliers and I only make it about 6 inches when I discover the vacuum hose off the switch mounted on the forward side of the firewall that I believe controls the BPV. Best I can tell from the manual, that's what it is. I reconnect the hose (it's tight, so it didn't just fall off!) and now the pump runs for a couple seconds and quits, as it should.

 

Looking at the service notes manual, section EMH.1, page 6, it's either switch 10, 11 or 12 - not sure because my car does not look like that illustration. I can't find a section in the manual that shows the actual configuration of my 95 S4, but I've not read the entire manual yet.

 

After re-connecting, I take the car for a drive get it warmed up real well, then check the IAC - I had not checked it since installing the new injectors, and it reads 8. So I adjust the IAC to 25 or so and go for a drive - very nice now.

 

I'm not sure what effect that vacuum leak had on teh car, the line that was off is tee'd into the other lines, so the pump was running all of the time and probably not providing the amount of vacuum the remainder of the affected systems were looking for because of the open line. Or maybe not.

 

Anyone know where I can find a description of the actual vacuum system on the 95 S4?

 

Thanks,

 

Jim



Here's a photo of the affected switch, the hose to the switch from the tee was completely off, hanging free. I'm quite sure this is the BPV switch because I traced the other two switches, one goes to the wastegate and the other to the fuel press regulator.

 

 

post-15426-0-53124600-1369938371.jpg

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Isn't there a schematic on the sticker inside the tailgate?

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Isn't there a schematic on the sticker inside the tailgate?

 

LOL, of course there is! Thanks for the reminder Bibs. Now it's definite, the EBPV was disconnected and its brother that tees into the disconnected line is the throttle jack capsule. Both are still installed, and I believe, functional - at least they are now!

 

post-15426-0-65677400-1369939298.jpg

If I remove the throttle jack and the ebpv, can I remove the vacuum pump? Or does it power other stuff in the cabin venting system as indicated by the parts catalog?

 

Jim

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No you still need the pump, just loop off the solenoids if your making them redundant

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