Hey everyone,
I’ve been dealing with a persistent fuel system issue for months now, i have tried everything I could think of without success and I’m a bit at a loss.
The current Issue:
My car consistently loses fuel pressure at the high-pressure fuel rail for a split second, dropping from 2500psi to around 100psi, causing a the car to go lean, it feels like you just fully let of the gas. Currently it primarily occurs when applying more than 70% throttle. Before replacing the high-pressure fuel pump, it would happen randomly and sometimes sit at 100psi for minutes.
DCT Codes:
I have gotten multiple dct codes over the last while. I searched for them but haven't really found anything that seems related to my issue. These codes also don't really come back that often, the last time they appeared was probably 3 months ago, even though the car has been having plenty of issues lately.
The first code:
What I've Done So Far:
Timeline of Events:
Additional Info:
My engine mods:
I have multiple forscan recordings available in which the issue is clearly visible, here are some screenshots:
I’m sort of at a loss of what the issue could be since I've literally replaced every component in the fuel system I can think of. The only thing I haven't looked into yet is an electrical issue, but I have no idea how I would debug this. I would really appreciate any suggestions or ideas. If you've encountered a similar issue, your insights would be invaluable.
I’ve been dealing with a persistent fuel system issue for months now, i have tried everything I could think of without success and I’m a bit at a loss.
The current Issue:
My car consistently loses fuel pressure at the high-pressure fuel rail for a split second, dropping from 2500psi to around 100psi, causing a the car to go lean, it feels like you just fully let of the gas. Currently it primarily occurs when applying more than 70% throttle. Before replacing the high-pressure fuel pump, it would happen randomly and sometimes sit at 100psi for minutes.
DCT Codes:
I have gotten multiple dct codes over the last while. I searched for them but haven't really found anything that seems related to my issue. These codes also don't really come back that often, the last time they appeared was probably 3 months ago, even though the car has been having plenty of issues lately.
The first code:
- P0251 (A13) - Injection Pump Fuel Metering Control A, Circuit Open.
- P2542 - Low Pressure Fuel System Sensor Circuit High, Circuit Voltage Above Threshold.
- P0087 - High Pressure Fuel Rail Fault.
What I've Done So Far:
- Replaced the high-pressure fuel pump twice.
- Replaced the high-pressure fuel pump tappet.
- Replaced injectors with 30% uprated double-sealed injectors and matching tune.
- Replaced the low-pressure fuel pump with a 340l/h pump from Pumaspeed.
- Replaced low and high-pressure fuel rail pressure sensors.
- Replaced the throttle body.
Timeline of Events:
- The trouble began this summer, approximately 3 months and 5000km after installing my new x48 turbo from Pumaspeed. Initially, my car experienced random drops in fuel pressure, first for a split second, mainly during acceleration, and later for minutes at the time every couple minutes.
- I then replaced the high-pressure fuel pump, injectors, and the fuel pump tappet. This appeared to resolved the issue for about 300km, after which the problem resurfaced with fuel pressure dropping to 100psi for a split second. This then happened again after another 300km.
- After another 100km the throttle body sometimes refused to respond to the gas pedal, refusing to open more than 20% until I let off the gas and pressed the gas pedal again. I replaced the throttle body, which sadly didn’t change anything and approximately 20km later, the high-pressure fuel rail would again consistently drop to 100 psi and stay there for minutes at a time, which would happen every couple minutes.
- I then replaced both fuel rail pressure sensors, which seemed to have fixed it for about 50km, after which the fuel pressure once again went down to 100psi for a split second and then after another 100km it again started going down to 100psi for minutes at the time.
- I replaced the high-pressure fuel pump for the second time while waiting for my new low-pressure fuel pump. This once again did not fully fix it and the fuel pressure now often drops for a split second whenever I apply more than about 70% throttle. The installation of the new low-pressure fuel pump over the last couple of days has, as expected, also not changed anything.
Additional Info:
My engine mods:
- X48 hybrid turbo from Pumaspeed.
- Pumaspeed Stage 3R 99 RON 4803 tune for 30% uprated injectors.
- Custom 3-inch exhaust.
- Cobra 3-inch sports cat downpipe.
- 30% uprated double-sealed Bosch injectors.
- Bosch high-pressure fuel pump.
- Pro Alloy competition intercooler.
- Pumaspeed R-Sport large-diameter boost pipes.
- Pumaspeed stage 3 intake.
- Forge blow-off valve.
- 340 Lph Uprated In-Tank Fuel Pump.
- Pumaspeed Racing Coil Pack.
- Collins Engineering wastegate actuator.
- NGK LTR7IX-11 Iridium Spark Plugs gapped to 0.65mm.
I have multiple forscan recordings available in which the issue is clearly visible, here are some screenshots:
- Red = Fuel pump duty cycle.
- Green = High-pressure fuel rail pressure actual.
- Blue = High-pressure fuel rail pressure desired.
- Yellow = Low-pressure fuel rail desired pressure.
- Pink = High-pressure fuel rail pressure sensor voltage.
- Cyan = Low-pressure fuel rail pressure sensor voltage.
I’m sort of at a loss of what the issue could be since I've literally replaced every component in the fuel system I can think of. The only thing I haven't looked into yet is an electrical issue, but I have no idea how I would debug this. I would really appreciate any suggestions or ideas. If you've encountered a similar issue, your insights would be invaluable.
