After a short trip of stop and go my 2001 A8 just shuts off and won't start for about 15 minutes. I just replaced the alternator recently, could this be the problem. The check engine light is no lit. On long trips the car runs fine. Seems like something is overheating only happens when car is stopped. please help.

 

The car is not starting in what way? No crank or crank no start?

 

It cranks over fine, seems like I'm not getting any spark. When it quits there is no warning sometimes I don't realize the car isn't running until I look at the tach. After it sits it starts right up.

 

I do not think it is the alternator if it cranking good.
At this point it would be best to have a scan tool connected to the car for fuel pump activations test , crankshaft & camshaft sensor data & fault code retrieval.
It would be best to have this done before throwing parts at your car , that can get expensive!

 

It only happens when the car is stopped and idling. The lights and fan stay on and the battery seems to be charging fine. since the alternator has the cooling hose I was wandering if it was heating up and shutting the engine off when the car isn't moving.

 

Thanks for your help, I didn't realize you could still get fault codes if the check engine light wasn't on.

 

I think M5S5 is right. Check fuel pump. If it is like 04, there should be one main pump and one transfer pump in the trunk. Mine does the same thing. Start would run and die without me knowing it. Made a mistake by listening for fuel pump noise. Heard it and assume it ok, what i was hearing was the transfer pump not main pump. U will still hear pump noise if one is still working. Best use omh meter to test pump. Good luck.

 

If you have the right scan tool you can get the pending codes. Keep in mind i have about 8-10 scan tools that read faults in obd2 vehicles & i find the best is the Vag-Com. It has the best capability to retrieve pending faults on VAG vehicles.

 

Where did you get the alternator? I would have it checked again as the symptons you are having are exactly what happens when an alt goes bad. I recently put a "new" one in my friends car and 2 weeks later it was shot had to exchange it for another one.

 

When my fuel pump went bad I have no MIL on. Plug VAG-COM in didn't tell me pump is bad.