Hello all...I have a 2007 GTI. Everything is in fine shape. Recently I switched back to my GIAC K04 HO(HO=RS4 fprv and a 140 BAR request for rail pressure) from a trial period with a DriverMotorsport K04 tune. My GIAC tune was fine a few years ago...but not the case when it was reloaded last year. The rail pressure request should be 140 BAR but only hits 110 BAR specified even though the actual exceeds that.
I have a USP High Flow lpfp(in-tank pump) and the mentioned condition is present with either the USP or OEM pumps...with the OEM pump currently installed. I cannot believe that both of these lpfp's are failing but cannot figure out what the problem is. Again, there are no fault codes and the filter and follower are nearly new. Additionally, with both lpfp's, the actual low pressure will drop below specified nearly 0.5 BAR each time I collect data for group 231 in the upper revs...6k to redline mostly. Earlier the pressure will match requested low pressure.
I've had recommendations to replace nearly everything like: cam follower, filter, hpfp, lpfp, fuel pressure relief valve, and the controller. But I think everything is in good shape other than the controller which I haven't heard of being the culprit to this. Only I haven't heard of anything being at fault for this, so....any others here ever experienced this? "This" being, everything runs fine...it is just that the high fuel pressure request is the stock 110 BAR rather than the tune limit of 140 BAR...