Fuel rail pressure at idle

[BradyBoi55]

Just wondering what the fuel rail pressure should be at idle. Thanks in advance!(I couldn’t find a thread stating what the pressure should be but did find one saying that the Fuel Pressure Regulator valve limits it to 125-130 bar)

[old guy]

560→575 psi at warm idle.

850→860 psi cold (fast) idle.

[Smac770]

4000 kPa aka 40 bar aka 4MPa
IDE00589 is high pressure rail pressure actual in kPa.
IDE00201 is high pressure rail pressure specified in MPa. No idea why they couldn't be consistent in units.

Lot of the SSP documentation is in bar. The high pressure system on our engines is 40 bar idle (mine tends to be 39 bar actual), 150 bar WOT, 200 bar design limit (where the HPFP should bleed pressure back into the low pressure line, which is of much larger volume). The low pressure side should be in the 3-6 bar range, relief valve in the fuel filter should bleed excess low pressure line pressure back into the fuel tank around 8 bar. But Audi got rid of the low pressure side pressure sensor for the gas engine; it's still there on the flex fuel engines.

(as old guy mentions, high idle will be a higher value, up to 6 MPa; there's a chart I made in some thread of the cold start high idle period)

[BradyBoi55]

So my warm idle is exactly 39 bar but my cold idle is only 700 psi… I have new injectors. HPFP next?

[Smac770]

What was the specified value? If the actual matches the specified, there's no problem.

[BradyBoi55]

What was the specified value? If the actual matches the specified, there's no problem.

I don’t recall. I’ll have to check again