[Spirit5676]

So under load the low fuel pressure fluctuates between ~2-10bar. While driving at constant speed there is only minimal fluctuation. I've checked it with ISTA+, INPA and Testo. Also the fluel pump Amps and fuel pump RPM fluctuate wildly under load low rpm high gear.  It might also drop the HFPF off (might do it or not), thus you get the engine light and it runs on only the low pressure. Following parts have been replaced, new original fuel low fuel pressure sensor, new Bosch low pressure fuel pump and a used EKPM (coded to the car). None have fixed the issue. As far I undestand the low fuel pressure should be 5 bar or close to it at all times. The high fuel pressure also dips under load, but it might be due to the low fuel pressure fluctuating wildly. I've attached couple of Testo graphs.


   

   

   

Anyone seen this before or have an idea what to check next?

[Beard]

Hello.
Replace fuel filter.
it is on the left side of the gas tank.
It comes with a fuel pressure regulator.

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