So after many problem free kmīs, yesterday i started the engine after being hot and standing for some 10 minutes. It started after a hesitation, but shut down immediately. Tried to start several times, but same result. No codes set. Was first thinking about the crank position sensor, but since it started, even for a short time, i discarded this option (at least for now). Listened for the noise of the fuel pump, but couldnīt hear a thing.
Later that day went back and it started, but was running rough for a while. Went home running normally, but halfway the check engine light came on. Checked the code with the keydance and it showed P0174: system too lean bank 2. Had a visitor over, so couldnīt look further into it.
This morning it started seemingly normal, eventhough the idle is not as smooth as it used to be. Went for some shopping closeby and after my return, put the scanner on it. O2 sensors 1-1 and 2-1 working normally, changing quickly from 0.2 to 0.8 back and forth. STFT (short term fuel trim) normal as well, going from -2 to +3. MAP seemingly normal, but when checking the LTFT (long term fuel trim), it came up with +25 at idle and +30 during driving. This means that the PCM is (trying) to add more fuel to the basic fuel schedule by increasing the injector pulse. From this new schedule (basic schedule + the compensation as shown by the LTFT), it was still doing its normal duty in respect to the STFT, fine trimming the fuel injector pulse to reach the best possible fuel mixture.
So this all leads me to believe that i have a too low fuel pressure. When driving faster and more fuel is needed, the mixture becomes too lean and the P0174 is set. (max compensation is reached, but with low fuel pressure, simply not enough fuel will be injected) So now i will look for a new fuel filter/pressure regulator and a new fuel pump cartidge.