austinado16

Here's a good one...

I've noticed on climbing long grades, that even if the climate control was off, or was in defrost, or floor mode, the ventilation would come "on" through the dash vents and be warm.

I've also had a slightly rough/fluctuating hot idle and although the CEL hasn't come on (other than for the EGR insuficient flow code during the first drive of the day) I have been getting a lean misfire code.

Put those 2 together, and I was pretty sure I had a vacuum leak from a vacuum line somewhere.

I've replaced all the 3mm cloth braided vacuum hose in the engine compartment, but still, removed the hose that goes to the top fitting on the right rear throttle body, hooked up the Mityvac and tested for vacuum. That system tested good.

Next, I removed the 3mm hose from the "Y" over near the brake booster. This comes from the left side of the throttle body, Y's and goes through the firewall to feed the heater box, and the other side of the Y goes down below the brake booster to "I don't know where."

Pulling a vacuum on just the line going to the heater box showed a nice leak. I removed the big plastic panel and with more testing via the Mityvac, I discoverd that the black rubber vacuum line running from the black/yellow valve across the top of the heater box and then into a "Y" to feed 2 other vacuum valves...was leaking from the clear vinyl "Y".

I cut the "Y" out, replaced it with a hard plactic "T" and then spanned from the "T" to each of the 3 black rubber vacuum lines.

That system then held a vacuum with the Mityvac attached.

Didn't get a chance to test drive because the wife had to get rolling, but I'm hoping I fixed both issues.

DaveInSaltLake

worse than all the other fittings in the Audi vac systems. The one on the driver's side of the firewall commonly fails and disables the cruise control.

Good work tracking that down. I need to get one of those Mighty Vacs!

egp320i

they must have PN on them somewhere or just ask and a good dealership should know what your talking about.

about failure, is it a cracking problem or do they collapse thus cutting off the pressure?

I think I've seen generic fittings like that at autozone or some place, not sure if you can or would want to use those though.

DaveInSaltLake

part of the plastic fitting inside the vacuum hose. I bought an assortment pack of vacuum fittings at my FLAPS and substitute in a tee where needed.

I'll have to check on the part number sometime and see if they're available.

austinado16

Clear vinyl ends which slide onto the various vacuum accuated valves, and then black flexible rubber tubing that's very thin. The "Y" piece was the same clear vinyl and glued in place.

So the "proper" fix would be to order the tubing assembly and pop it on.

A plastic "T" and 3mm cloth braided hose going from the "T" to the thin rubber lines is plenty permanent though.

egp320i

sounds like something you can get at pepboys, autozone and the like without a trip to the dealer.

austinado16

Yep. I went to the hardware store 1 block away and bought a T for drip irrigation