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My Audi A4 (2003, 1.9 TDI AVF engine, manual) sometimes decides to stall while driving, so far four times this winter. Engine will start successfully after a minute or two, otherwise I can hear it try but it kinda sounds like it gets no fuel. Once it starts it works just fine until it decides to stall again. This only seems to be happening in colder temperatures (5 and below degrees celsius) and once it starts the smoke coming out of exhaust is darker for a second, then returning to normal - though I've only seen the smoke once. It seems to stall only while driving between 10-~70km/h and right before it stalls it will sort of shake a little.

The ECU does not seem to be reporting any errors. I have checked it (Engine, Cent. Electrics, Immobiliser just in case as well) after it has started up and worked for a few as well as immediately after it stalls, without turning the engine on.

It has stalled one time last winter, however me and others believed it would just have been bad quality fuel.

So far replaced the fuel filter, but it has not helped. A few local mechanics have had a look at the fuel lines and they have not confirmed any air bubbles or similar. Next on my to-do list is to replace the crank shaft position sensor, as it seems that some people (on the Internet) have reported it to be causing similar issues.

What could possibly be the problem? Would there be a checklist of what to inspect in cases like this?

  • I'd hold off on blindly replacing components. If you suspect the crankshaft sensor either scope the signal or watch scan data using a trigger if your software supports it. If the signal drops out the RPM PID should drop to zero immediately. – Ben Feb 24 '17 at 23:29
  • watch out for pending codes, I had a stall that eventually registered as a CEL once it unfolded a few times. An early pending code could let you do some research to feel out what may be going on. – jxramos Feb 25 '17 at 0:19
  • The only software I have access to at the moment is VCDS Lite (which should support my car model - and it seemed to in the past) but no DTCs are stored in the Engine area. I apologize if I'm not as experienced as I should be - everyone keeps telling me the car is fine because the problem isn't easily reproduced (it doesn't stall when they test it!) – Paweł Adamski Feb 25 '17 at 0:24
  • I had a stall that was intermittent, at first it started out as a hesitation, then hesitation and shudder/stutter. Then in progressed to an outright stall that restarted when I keyed up the ignition. My situation was a faulty fuel pressure sensor, which the DTC was pretty good about highlighting for me about a pressure sensor reading high or something. – jxramos Feb 25 '17 at 0:31
  • Is it possible that the injectors are failing? People tell me the engine should have trouble starting cold if injectors are failing, but what are the chances they only sometimes fail? – Paweł Adamski Feb 26 '17 at 6:36

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