Hot start problem

[Simon87]

Got a really unique problem for the model of Audi.... Searched high and low for a solution to this problem and really can't find one.

Basically after the car is up to normal operating temperature and stop the car won't start unless I pump the accelerator.... Starts first time everytime in the morning or when the car has cooled down.... Had the crankshaft sensor replaced at great expense and thought that would solve it but it hasn't....got a new battery as well and again same issue

Any ideas or pointers would be fantastic 

[Magnet]

Hello Simon,

Of course, this could be due to numerous issues, and dare I admit it - might need plugging in to assess fault codes.

If it were mine:- 

I'd be talking with some of my friendly taxi boys and seeking their advice on a trusted local diesel specialist. (I would not be taking it to Audi or an independent).

They should be able to run the necessary tests for you, and this may include a leak-back test on the injectors. 

As you have found with replacing the crankshaft sensor ( replaced with Audi part?) you could otherwise end up changing components without any improvement, and indeed potentially introducing additional problems, since replaced parts may not be as reliable as the originals. 

As a matter of interest, any smoke or diesel fumes when it does eventually start when hot? 

Kind regards,

Gareth.

[Badgerman]

Simon - really can’t help, but had the exact same thing with my 1.9 TDi A3 from some years ago. Starts perfectly cold, when hot just crank away......I never found what it was, but the black smoke which came out on hot start seemed to point to injectors. A pal wondered if someone had filled it with petrol and damaged the nozzles, was never sure if that was right but I had no other explanations. 

Good luck. I feel your pain!