Q&A

 Master

I have seen reports where the EVAP purge valve sticks open and causes a vacuum leak, which causes a very hard start. It sits on top of the Air Cleaner. When the car is starting it should be closed and should not open until the car is running and is in a 'purge' mode. I have talked to techs who have pulled there hair out for weeks before finding this. Hope this sheds some light. You can bypass it for testing purposes and see if cahnges anything. It costs nothing for this test. Another thing to consider is to look at the fuel trim, especially Long Term. Audi's tend to wear out their Mass Air Flow Sensors pretty quickly. The Long Term Fuel trim will be over 12 percent. This creates a lean condition which can cause a hard start. It may also have wiped out your CATS. When the car is too lean, the CATS are flooded with HC's and NOx and they get over worked and fail. I hope these tips shed a little light.

 Journeyman

If during the hard start episodes you are able to confirm that fuel pressure AND fuel volume are correct , that spark is available and sufficient and you have no air leaks plug the evap as suggested and try starting with the MAF sensor disconnected.
Incidentally is residual fuel pressure maintained after shut off ?? Sometimes necessary for starting after hot shut off.

 Enthusiast

what codes did you get for the cat codes because i am wondering if I need to change my 02 sensor or my cat