1999.5 Audi A4 1.8T Quattro with 122k miles

So i woke up this morning to get to school and i put my key in the ignition and my car wouldnt start. It would crank but the engine wouldnt turn over. I just installed a boost gauge a few days ago and a K&N cold air intake about a month ago but i doubt these could have caused the problem. I popped the hood and saw nothing out of the ordinary. Went back into the car and turned the key again and held it there for a long while while playing with the gas pedal, i started to feel the engine turn over but it quickly stopped. I tried one last time holding the key and playing with the gas again and it finally turned. The engine turned over hard and was shaking a bit and it idled at about 1100 RPM. I went to the hood and gave it some throttle to try and clear the cylinders a bit, and dark smoke was coming out from the engine and my intake was shaking a bit too. I thought it might have been some bad oil, or not enough so i added a quart and it seemed to work. The car now starts normally and idles at about 800 RPM like normal.

My question is what the hell wnet wrong so i can fi it before it happens again. I was thinking maybe a bad fuel pump, spark plugs, ignition coil or maybe it was a fluke?

 

so you just randomly added a quart of oil? that's not a very good idea man. check the oil level first. the dark smoke if from all the gas that was pumped into the engine when you were trying to start it so it's normal. i would go get the battery checked.

 

im with hiwords, sounds like your battery is on its way out. Changes in temperature cause batteries to go bad if they have weak cells already.

 

i agree with not adding oil without checking the level first but electronic fuel injection doesnt work unless the system is running, so.holding the gas down when trying to start it wont really harm it.. its not carburated, where this would flood it.

 

If your engine coolant temp sensor is dead/dying, you will have hard cold starts. With 122k miles, and being a $7 part,its a good idea to replace it anyways. Im not even going to flame you for adding oil without checking the level first, let alone for thinking lack of or bad oil is the cause of your problem...................

 

Alright im not a complete *** lol i checked the oil level first and it was low, thats why i added the quart. Im not sure its the battery all the electronics ran fine as well as the lights. In any case, i changed the battery about a year ago and i would hope it wouldnt die that quickly?

 

It could be a fluke. If it starts happening more often, replace your ECTS. If the ects is bad the ecu will get confused, **** its pants, and not know how much fuel to dump in the cyl's. Depending on wether your sensor goes north or south (signal too high/too low) you will get either a rich or lean condition.

 

did you try starting it with the head lights on? if so did they dim at all?