View Full Version : TDI engine sounds to be missing / out of balance after running for a while

25-09-2007, 03:15 PM

My 1.9TDI runs like a treat for the first 30 mins or so but after this time (once it is warm I guess) there is a lot of black smoke out of the back if I put my foot down and when idling the engine sounds like it is missing / out of balance. When I leave the car over night or for a few hours it runs ok again until it has been running for a while and then the same again. I took it to a mechanic who deals with Audis and he has not heard it before. Thinks it may be part of the circuit that passes the exhaust gas around to the turbo / exhaust etc. or possibly a sticking valve.

Another update: Had a mechanic look at it and after looking over / under / into he thinks it could be the fly wheel out of balance. Does any of this sound feasable? If it is the fly wheel could it be terminal?

My personal ealing is that it might be a leaking pipe.

Other details:
1.9TDI (130), 110000miles, Auto, 04 Plate

Ideas / suggestions welcome!

25-09-2007, 09:31 PM
Hmmm, a couple of things that are always worth trying...

1. Disconnect the connector to the MAF and see if you notice any difference in running the car, this doesn't automatically mean it is the MAF, this can help diagnose a problem related to the turbo.

2. Pull the vacuum hose from the EGR valve (this is the silver disc you see poking through the top of the engine cover). I had problems at idle, black smoke, stalling because of a faulty solenoid to do with the EGR.

25-09-2007, 10:36 PM
Coolant temp sensor would be my starting point, these fail a lot and could explain the black smoke if it is overfulling do to a faulty sensor tricking the ECU into thinking the engine is cold.

26-09-2007, 09:12 AM
There's a few threads on this recently that are very detailed in this kind of thing, have a look through the B6 & General A4 sections and you'll get all the options. Flywheel out of balance is a load of bull do-do, your mechanic is obviously not as Audi proficient as he's making out!!

26-09-2007, 02:13 PM
There is a cam position sensor just underneath the cambelt, my (carís) sensor failed and the engine idle very rough, it felt it was running on one cylinder, at the end my car couldnít start. Some days it was working fine. (I guess thatís why VAG said intermittent...)