Vac Leak help, yes I searched...

[DownhillA4]

I'll try and keep this short, all the details.

Check engine light came on close to home. Pull in driveway, revs are bouncing. Stopped the car and it's idling at a stand-still and check engine begins to flash. Pull the codes: p0171, p0300, p0301, p0302, p0507. Loud hissing noise coming from behind the intake manifold at the back of the engine bay. Since it's a Cylinder 1/2 misfire only, I went ahead & swapped both of them out with new coilpacks, obviously no difference. Being only a misfire on 1/2 I assume it's a "point" vac leak, and not multiple. Went ahead and removed MAF, that's not it. Also later tonight, started it up and slowly revved. Everything calmed down at 1500rpm/above and check engine light went back to constant rather then flashing. Anyone have any ideas because this car is not drive-able.

To top it all off, inner CV boot on drivers side front completelty seperated slinging grease all over (whata' coincidence). When it rains, it pours. Thanks for any help guys, I appreciate it!

[BASARAB]

Check this hose http://www.audizine.com/forum/showth...ses?highlight=. On my car cause of p0171 code was small hose,which looks like small "h", which is connected to suction jet pump and check valve

[old guy]

I suspect you have a split suction jet pump.

[DownhillA4]

Thanks for the info. Anyone else ever have a similiar problem?

[[email protected]]

Yep, probably your suction jet pump or your crankcase vent tubing. These two would explain the hissing you are hearing.

[Elliott]

Thanks for the info. Anyone else ever have a similiar problem?

Sounds exactly like what mine did when it split. You can glue it back together until your new part arrives. Fortunately, they're only $25 or so.

[EBG 18T]

Thanks for the info. Anyone else ever have a similiar problem?

mine just failed last week. similar symptoms

[diagnosticator]

If the lean mixture misfires are only on cylinders 1/2, then the vac leak is most likely in a hose connected to the intake manifold near the intake manifold runners for those two cylinders.

[fla4sline]

Yep, that's exactly what happened to me, codes and all!!!
First it started with the hose that BASARAE links to, then a couple of check valves, then just couldn't find the leak. Checked the MAF and changed the rest of the check valves and most of the hoses, then the DV and crankcase breather valve, and after much money and frustration had to take it in to a mechanic who found it was the suction jet pump in minutes. At least all of the hoses and valves are replaced now and I have spares for the future.
As for the inner CV boot, I couldn't find a DIY for inner CVs, just outer only. There is alot of discussion on here about this subject. VW/Audi axles are solid and very robust. Some ppl say to just get a rebuild one, while others just fix the boot. I had mine done by Audi just last month. I don't mind getting my hands dirty, but this looks like a PITA. A shop should be able to replace the boot relatively cheap.