Hello,

 

My 2005 Octavia 1.6 FSI became undriveable while in a long stop/start queue.  The engine was shaking and the rev counter was all over the place.  The throttle wouldn't do anything and the only way I could move the car was on the starter. When the AA arrived after 45 minutes it ran fine and nothing showed up on his computer.  

 

I have managed to reproduce this on my driveway several times (never fails to show up) by driving the car until it reaches normal temperature and then leaving it idling.  After 15-20 minutes it always behaves as described.  I took it to a garage and they diagnosed a lack of fuel and replaced a fuel flow sensor but it made no difference.  They have now admitted defeat.  I have arranged for a mobile auto electrician to look at it in about a week's time.  Does anyone know what the cause of this might be?  I daren't drive anywhere which is likely to have a long slow moving queue.

 

Thanks in advance for any advice.  Bear in mind that I am not technically minded.

 

David

Needs plugging in to see what fault codes you have. You could have fuel pressure problems. Have you ever changed the fuel filter under the tank? For good fuel pressure everything on the low pressure side has to be perfect.

The car will need more fuel when driving than when idling on the drive so unlikely to be filter related. I would be looking at increased heat under the bonnet causing some breakdown of a component.

First thing i'd look at is fuel filter. 

 

I agree with TinBum's theory but in practice I've seen the opposite (because cars are stupid!). 

 

When I did my apprenticeship the boss always said "Start with the basic, obvious, cheap to do stuff & work your way through".  Can't get much more basic / cheap than a fuel filter.

 

The next thing would be to check fuel pressures.  I believe these can be logged with VCDS or similar.  this might signify if it's the lift pump at the fuel tank or the High Pressure Pump on the engine.

The auto electrician diagnosed the HP fuel pump was at fault.  Pressure was lower than normal at idling and It was getting very hot indicating the bearings were on the way out.  Apparently the Skoda technical info sheet indicates that it is a known issue on the FSI engine.   

I'm curious what the final word on this situation was. I'm having similar problems and have come to think it could be the EGR valve. Any thoughts for or against this?

It's rather a long time ago now but there was a work around.  The error codes indicated a fault on the low pressure fuel supply but a replacement pump did not cure it.  I could always reproduce it by leaving the engine idling for about 20 minutes. Something was overheating since it never happened with the bonnet up. As it was winter I was running the car with the air con in Econo mode which meant the fan was rarely on.  Switching to AUTO meant the fan was always on and I then couldn't reproduce the fault with it idling for 45 minutes bonnet down.  So that's how I've left it.  I used a mobile auto-electrician and he couldn't get to the bottom of it either.