2.7T Will NOT start with warm engine
 

I have been driving this car for four years and it recently quit starting when the engine is warm. It does not always happen, just on occasion. I can hear the fuel pump start when I turn the key on, but the engine does not fire at all. The battery is one year old and the engine cranks the same both cold and warm. If I wait long enough (about 30 to 45 minutes) the engine starts and there are no symptoms or fault lights. Any help would be greatly appreciated. Thanks

What year and mileage?
Have you replaced the fuel filter?
It could be your MAF or a fuel starvation issue (clogged filter or fuel pump getting old and tired).

It is a 2000 model with 136,000 miles. I have not replaced the fuel filter, but I certainly will. Would the car sputter and attempt to start if there was partial fuel? It acts like there is no spark or that the fuel injectors are not releasing any fuel at all. I would have hoped for a check engine light as this would have revealed something. Thanks

hmm, maybe coils? Ive heard that those can be a problem.

The car has individual coils for each spark plug, so all six coils would be failing at the same time. I would be worth a try if there was one coil. Thanks for the suggestion and input. I am hoping that someone has stumbled across this unfortunate situation and has a solution. It is hard to trouble shoot as the car starts most of the time.

Well my 2.8 has 3 coils and I know they go bad and I have read about problems on 2.7T coils as well. I know that when we had our passat 1.8T, 2 of the coils whent out at the same time(~95000mi) and we replaced all 4 just to be safe. These VW/Audis are incredible, its like the engineers worked in all these intermittent problems just to drive us mad because we cant get em fixed, lol. Good luck!

could be the fuel pump, happened to me.
it would start cold, then warm up and die. replaced it and all was well.

I just got done waiting 45 minutes before the car would start. I was in town and shut it off for 10 minutes (Bad Idea). I did not have any tools and was not about to start troubleshooting. Once the car cools down enough, it starts right up again. Once it is running, it stays running ... ??? The local Audi service department has no ideas, just bring it in and they will attempt to find the problem. Thanks for the input from the Forum. I hope to have the fuel filter replaced tonight along with new plugs.

recently I had a similar problem and replaced the fuel pump, filter, fuel pump relay and crank postion sensor trying to figure it out. It turns out its actually the alternator, and if you do stop and go driving, the rpms do not go high enough for a worn out alternator to charge the battery as well as the brake lights drain a lot of the power at stop lights. The "cool off" period seems to allow the battery to get more chemical energy while sitting (kinda like taking the battery out of a dead cell phone and waiting to put it back in) and will start after some time. Not 100% sure you have the same problem, but checking an alternator isnt too hard and wont hurt.

Really outside chance: the coil packs are controlled by two, err...controllers. One for the right bank, one for the left. They're mounted on the side of the airbox, and sometimes get a little wonky. Both of them failing at the same time would be really odd, but would certainly kill the spark. Perhaps if you're in a warm climate and it's getting really toasty under the hood, I guess it could happen.

Someone suggested to check the alternator; a good place to start, as that's pretty easy to check and see if it's putting out enough juice. The ECU can start to act all sorts of odd when it's undervolted. Though you have a new battery it could be that you got a defective one, so when it's put under load to crank the engine, it'll crank, but there's not enough juice left over to make the ECU happy.
Easy way to check: Jump-start the car when it's hot and won't start. If it fires right up, you have a good indication that it's your battery that's causing the mess.

Let us know!
-Red