hi all,

Seeking a word of advice.

Here's the scope.

I’ve been having random cylinder misfire problems all along but just recently I had the car (2001 S4) began to manifest more visible symptoms, a few times last month I had problems with starting the car. I started the car in the morning, drove it cold for a few miles turned the engine off, then it would not start at all even though starter is working just fine. I left it at the parking and came back few hours later – it would start right up.

Also, when driving the car and going over 3k rpm it would give me occasionally a single ‘thump’ as if the engine cut off for a split sec.

A week ago or so I ‘ve got the camshaft position sensor replaced, as per code: P1338 Camshaft Position Sensor (G40) Open or Short to Plus. This seemed to have cleared the codes and check engine light came off. The problem with inability to start the car still persists though. I haven’t had time to do anything with it, but it seems to be manifesting itself now even more.

When cold the engine starts just fine, then when I try to start it after having it run for some time it will not start until I give it 0.5-1.0h to sit. I tended to believe it was the fuel pump going, as a couple mechanics suggested that a fault pump might to be retuning unused gas back to the tank…now i'm lost. Any ideas?

Now, the car shuts down on me after driving a mile or so and I will not start back up unless I let it sit and cool down, etc.

I had it scanned at AZ on my way home and the following codes came up: catalyst efficiency low-bank 2, possible causes:
1 - catalytic converter defective (failure possibly due to #2, 3 or 4
2 - engine misfire
3 - large vacuum leak
4 - engine oil leakage into exhaust-valve guide seals.

Any ideas are appreciated. TIA

 

i would check for a vacuum leak... it's the least expensive on your list...