seemed to confirm

thats why it's a return less system there is no fuel pressure regulator to limit how much gas goes back to the tank.

like the B5's use.

B6 models use 8E0 906 087P fuel pump and 441 201 511C

The B5 uses 8D0 906 089A fuel pump and 441 201 511C non DBW and DBW cars...

the B5 and B6 use different relay but other than that nothing in the lines that i can find on the ETKA...

but this is my findings on the ETKA and EIS CD. if there is a regulater that would be news to me :)

Don't ask me to explain it, I'm not even sure I understand it....

The fuel pressure regulator is located in the fuel filter underneath the tank.

Fuel pressure regulator regulates fuel pressure according to intake manifold pressure. This ensures that the pressure drop at the fuel injectors remains the same for each speed and load range of the engine.

the B6 forum there is no manifold feedback as in our system. In the B5 system the pump delivers fuel at x psi. At idle the manifold vacuum lessens the fuel pressure via the rising rate FPR such that the injector nozzle sees a constant delta between the fuel pressure and the manifold pressure. As vacuum in the manifold rises to zero the pull back on the FPR also lessens toward zero. At positive pressure the fuel supply pressure rises 1 to 1 along with manifold pressure keeping the delta between fuel pressure and manifold pressure constant.
My understanding of the returnless fuel system employed in the B6 is the pressure regulation is in the fuel filter assembly below the tank. There is no manifold pressure feedback loop to the B6 FPR. The link is to one of the many arguments about the adequacy of the B6 system to deliver fuel above the 210 hp range. If you ignore the bickering there is some info about how the B6 system works.<ul><li><a href="http://forums.audiworld.com/a4gen2/msgs/28514.phtml">http://forums.audiworld.com/a4gen2/msgs/28514.phtml</a</li></ul>

and didn't rise/fall with boost/vacuum.

But, theoretically, the ECU could use the pressure sensor to control the regulator, but I'd have to see the wiring diagrams to find out if that's even possible.

Personally, If I had a B6, I'd buy the return lines, fuel pump, etc, the V6 used, and install a FPR up front and go to a nonDBW setup :)

Count the hooves &amp; divide by the square root of 16?

:-D

Why not just run a regular fuel rail, adjustable FPR, and run a second line back to where the filter is, and do the necessary changes there?

gas pedal 'feel' ...

it's not going to like a FPR up front

manifold pressure referenced.

For instance, you have 45 psi of fuel pressure. Add 15 psi in the manifold and your effective fuel pressure is now 30 psi. You just effectively made the injectors ~30% smaller. A manifold pressure referenced FPR will raise the fuel pressure (usually) 1 psi for every 1 lb of boost it sees in the manifold to keep the effective fuel pressure the same across the board.