Audi Repair: A4 2.0 FSI. too much fuel pressure - help!, pressure regulating valve, high pressure pump

Question
The timing belt recently went and the repair has been carried out. Unfortunatly the car is still in "limp Mode" as there is too much fuel pressure (190psi). Two garages with Bosch experts have had a look and cannot figure it out. Its been over a month now and I'm hoping you may be able to help? please? Chris

Answer
Hi Christoph,

When you say the timing belt 'went' do you mean it broke?? if so I am presuming that the cylinder head had to be removed to replace a valve or two.

Was everything replaced properly?? there is a high pressure pump located on the head it self that takes the pressure from the tank (supplied by the fuel pump in the tank) which is 6 bar up to approximately 50 bar at idling and 110 bar in certain parts of the operating range.

there is a fuel pressure regulating valve (N276) on the pump it self that is electronically controlled, either the valve has a mechanical problem and is stuck or an electronic one and is not being controlled properly by the engine control unit.

I suspect that the fault is mechanical, due to the work that was carried out, have the pump removed and check if everything is sitting properly and that they are installed correctly. i know of a few cases where the valve it self breaks, remove it for further inspection

also try removing the socket that goes into the valve with the engine idling and see if that makes any difference.

Also please note that due to the high pressure the pipes have to be tightened properly and free from tension,
after carrying out any work on the system  check for leas before driving off or else you might end up a bit too well done!!!!! :)