Hi there, I have a 1994 Audi Cabriolet, runs like a dream.  On Saturday whilst driving at 60-70mph, I lost all power in the car.  Came to a stop, safely thank god, and tried to restart it but was completely dead, as if I hadn't activated the immobiliser.  90 mins later when the recovery man arrived, it started fine and I drove it home.  The next day, I was 2miles from home and it did it again, same thing happened, an hour later it started again.  Am assuming its electrical or the immobiliser, but would it kick in whilst driving>  If not, then any ideas on what sort of electrical problem this could be. Thank you

Have you thought about the fuel pump or fuel pump relay?

Autoelectrical guys have check it but 20year old car.  Have checked all the relay's on it.  When it dies, it is literally dead.  Does not turn over, can't hear the pump, then an hour later all starts as normal! arrgghh

So definitely not the fuel pump then?

No because my mechanic has had the car for the last three weeks and its run fine.  When it dies, everything dies, although lights on the dash flash.  Its like the immobiliser hasn't been activated when I try to restart it.  Leave it an hour and it starts up no problem.  They have now disconnected the immobiliser and going to try it for another week before I take it back.  Lost all faith really. :-(

Any progress with this?

Mechanic had the car for three weeks and drove it around and the car behaved so as a start he has disconnected the immobiliser.  He is thinking if it is not the immobiliser then if the car does cut out again, at least it may start straight away.  The hour or so it won't start he thinks is the immobiliser resetting.  So basically, no.  He said it could be the crankshaft sensor but while the immobiliser is attached he won't know. 

I think James it right re the relay because I had exactly the same problem with a MkIII Golf many years ago. The engine would die, but you could hear the fuel pump when trying to restart. After taking it to a number of specialists, one of which replaced the fuel pump, and disconnecting the immobiliser it was still happening. I joined the AA as a last resort and when it broke down, luckily for me the guy knew exactly what it was; a faulty relay. He popped the cover off and wrapped an elastic band around it and it fired up straight away. I think the relay was only about £10 from VW in the end too.