OKay i have a rel brain picker here, This is 2004 audi a4 1.8t quattro. 80xxx miles. about 600 miles ago i have replaced : timing belt,water pump, serpetine belt, all 4 coil pack, all 4 spark plugs. car has run flawlessly starting 2 days ago my car gave out on me while driving just came to a complete stall i couldnt get it running again. it got juice never the less my batt light never came on. i changed the fuel pump and the car started to run again, yesturday while driving to work i got a check engine light and the car started to sputter at random times, idling or driving. i got it scanned with the obd2 nd it said i was running lean. last night my car wouldnt start what so ever i got a brand new bosch battery thinkin maybe the batterys dead and it wont crank. that didnt seem to fix the problem. i had a friend mechanic stop by and scan it with the audi tool and got no codes. never the less my check engine light is now gone and the only thing thats lighting up is the traction control. we came to the conclusion that maybe now a fuse got blown but nope i checked that, this morning i put a brand new bosch fuel filter in and the car starts up and idles just fine and after about 10 seconds the rmps go down until the car completly dies. Im assuming it might be a vaccum leak but its weird that im not getting a check engine light on. Im going bak see if i can follow the vaccum lines to see if maybe one check valve is bad or so. but if anyone has any ideas let me hear it . bc i am absolutely out of ideas now... im starting to hate the vw/audi corp....

 

have you checked for fuel pressure at the rail? could be fuel pump relay? Maybe the replacement pump was bad. Maybe o2 sensor, maybe injectors? Just throwing out some things to look at. Start with the rail pressure though. Turn the key over to make sure there is fuel spray, then wait 10-15 mins with the key still turned on and try again.

 

OHHH also look at the MAF. Unplug it and see if you get a diff result than you are getting. Its the big plug by the airbox

 

I have seen several cars with interlocks on the brake pedal switch. bad switch = no start or track control light/ abs light on.