Hi,

This is my first post using this forum as I am a new Audi owner as of last week. I gave searched high and low for this problem and have come across some good info, and have also tried all suggestions so far.

The car is a 2005 A4 2.5TDI Cabriolet, 74000 miles, 6 speed, front wheel drive.

I am having problems when it comes to starting the car from cold which I have read about and have tried most things so far. When turning the key it takes longer than usual (about 6-7 seconds) to start, followed by a cloud of smoke which Im assuming is excess fuel. It starts fine when warm.

I have so far changed glow plugs, fuel filter, camshaft timing sensor, coolant temp sensor with no results. The coolant temp sensor was suggested because if I unplug the sensor the glow plug light stays on longer and the car starts perfectly! Had the car plugged into diagnostic equipment with no fault codes.

Starting to lose hope now so any help would be appreciated greatly. Next I was thinking glow plug timing relay but I am just guessing now.

Thanks,

Phil

 

Hi

I have an A4 2.5 TDi with 76000 miles on the clock, and I am having the exact same problem. I sent the car in to Audi, and they kept it to overnight to attempt a cold start the next morning. The car apparently started on the turn the next morning, and everything showed up OK on the diagnostics check. I also suggested the glow plug timer relay to them, but they said that if it was faulty, it would show up on the diagnostics check. Something that I did come across whilst browsing the net though is that the fuel injectors may be leaky, and may be dripping fuel from the line into the cylinders while the car is standing. Hence, when the car has been standing for a long time (e.g. overnight), more heat is required to heat up the excess fuel in the cylinders to get the engine started. This would also explain the huge puff of grey smoke out of the exhaust. The leaky fuel injector theory seems like the most probable explanation, but knowing Audi’s labour and part costs that would probably be involved in fixing something like that; I have decided to rather live with the problem for now. The problem is not so bad in summer, and I have noticed that as long as the ambient morning temperature is above roughly 20 degrees Celsius, the car starts on the turn from cold more often than not. Winter is a different story though. In any event, please let us know what your progress has been. It is a great vehicle, and this is really the only problem that I have with it right now.

Regards,