I have a 2000 BMW Z3 2.5L. I've got P1188, P1189, P0170, P0173 codes. I did a smoke test and fixed all the leaks (replaced the CCV valve and associated hoses), replaced all O2 sensors, and replaced MAF. It didn't help.
I checked the fuel pressure and it was 1PSI above the upper value of the range prescribed for the car. I replaced the fuel filter, fuel pressure regulator, fuel pump, and all fuel injectors. It didn't help. I changed the fuel tank breather valve and that helped, but not completely. It takes longer now for the codes to return.
Because of the higher fuel pressure, I suspect a clogged fuel return line (the fuel tank breather valve is connected to the fuel return line either). I used the 'liqui moly fuel system cleaner' and it didn't help.
Have you ever attempted to either replace all the fuel lines (especially the return line) or unclog them with compressed air? Can you think of any other cause for the higher fuel pressure?
Can you think of anything else that could cause the codes? How about resetting the trims?
I checked the fuel pressure and it was 1PSI above the upper value of the range prescribed for the car. I replaced the fuel filter, fuel pressure regulator, fuel pump, and all fuel injectors. It didn't help. I changed the fuel tank breather valve and that helped, but not completely. It takes longer now for the codes to return.
Because of the higher fuel pressure, I suspect a clogged fuel return line (the fuel tank breather valve is connected to the fuel return line either). I used the 'liqui moly fuel system cleaner' and it didn't help.
Have you ever attempted to either replace all the fuel lines (especially the return line) or unclog them with compressed air? Can you think of any other cause for the higher fuel pressure?
Can you think of anything else that could cause the codes? How about resetting the trims?
