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The vehicle is experiencing misfires, hesitation, and a decrease in power.

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Greetings, I am a newcomer to this community and I own a BMW 116i 2008 equipped with an N43 engine.

My automobile has been reliable for the previous 3 years, but it has suddenly encountered issues that are difficult for me to identify. I would really value any counsel since this matter has been causing me significant distress for a considerable period of time.


    Encountering subpar performance when driving at high speeds on the motorway (vehicle lacks power). I encounter both hesitation and jerkiness while initiating acceleration from a stationary position, as well as sometimes when driving uphill.

    Upon experiencing this, the EML light on the dashboard illuminates intermittently, and thereafter, the automobile often exhibits misfires accompanied by an abrupt decline in power. Upon rebooting the vehicle, it resumes seamless operation.

    The car's engine only sometimes revs while it is not moving. (I have come across information suggesting that this issue might be caused by a malfunctioning NOX sensor).

Codes that have been saved or recorded:

The scan of my automobile has produced the following freeze frame data:

Please note that the only code that is presently active is 2AAF. (I believe that the occurrence of misfire codes and map thermostat activation codes is solely attributable to the aforementioned issue)

2AAF: DME: current fuel pump plausibility

    The frequency is 40.
    The distance covered by the logistics counter is 40 km. Distance travelled: 217,384 kilometers Fuel consumption rate: 2.00 litres per hour Fuel pressure prior to fuel supply control valve: 3,523.66 millibars Engine RPM: 1,024.0 Voltage at terminal 87: 14.32 volts

Diagnostic Trouble Code 29CF indicates a combustion misfire in cylinder 3 of the Direct Injection Engine (DME).

    The frequency is 2. The logistics counter is 40. The load value misfire detection is 11.72%.
    The engine is running at a speed of 2656 revolutions per minute. The temperature of the engine is 82.50 degrees. The presence of oxygen is detected. The sensor integrator group 2 has seen a decrease of 7.03%. The kilometre reading is 217,616 km.

2EF7: DME: Activation of map thermostat

    The frequency is 31 and the logistics counter is 40.
    The current state of the engine is PL.
    The engine is running at a speed of 1024 revolutions per minute (1/min). The temperature of the engine is 31.50 degrees. The voltage at terminal 87 is 14.32 volts. The distance travelled is measured in kilometres (KM). Distance travelled: 217,384 km

A6CF: Requesting immediate repair for the JBE AUC sensor.

    The truck is travelling at a speed of 65.40 kilometres per hour. The frequency of the vehicle's movement is 2. The logistics counter is now at 28 km. The reading is 217,768.

The 2AF6 code refers to a Lambda binary issue with the DME nitrogen oxide sensor, which may be producing problems.

    The frequency is 48 and the logistics counter is 36 kilometres. Distance travelled: 217,472 km
    The engine status is now PL.
    Engine speed: 2144 revolutions per minute (rpm). Engine temperature: 84.00 degrees Celsius. Voltage at terminal 87: 14.42 volts.

The 2AF4 is an electronic nitrogen oxide sensor for DME, which may be producing problems.

    Frequency: 255 Logistics Counter: 40 Kilometer Reading: 217384
    The engine status is now PL.
    Engine speed: 1536 revolutions per minute (rpm). Engine temperature: 92.25 degrees Celsius. Voltage at terminal 87: 14.42 volts.

Completed tasks:

    I have just changed the Low-Pressure Fuel Pump (LPFP) and filter, resulting in a modest improvement in the vehicle's performance. I refrained from deleting any scripts or making any adjustments to the set.

    Substituted the low-pressure fuel sensor subsequent to the activation of the low-pressure sensor code.
    After experiencing troubles with the ABS wheel speed sensors, I cleaned them, which resolved the particular problems.

Upon bringing my vehicle to a shop, they have recommended replacing the spark plugs, injectors, coil packs, and thermostat. Additionally, they have suggested changing the reluctor rings, however I have temporarily resolved the problem myself. I am unable to financially support or undertake this approach.

I have purchased the Foxwell nt-510 Elite and I would like to provide you with some data in the hopes that you can identify any issues:

Data collected during a fault:

    The gasoline low pressure value is between 3302 and 3646 hPa.
    The fuel high pressure value is within the range of 139136 to 150982 hPa.


Real-time data without any errors detected when the system is in a state of rest.

Please take notice that the data provided was collected in homogeneous mode conditions, as indicated by the programme. It seems that my vehicle only operates in this mode, as the coolant temperature remains between 80 and 90 degrees when driving.

Data about the low-pressure fuel pump:

The pressure of the lpfp (low-pressure fuel pump) fluctuates between 3414hPa and 3548hPa at idle, with a variation of 134hPa. This indicates that the lpfp is not maintaining a consistent pressure of 5000hPa.

After the engine has been turned off for 15 seconds, the pressure reading drops to 2987hPa, which is below the minimum value of 4500hPa. This indicates that the low-pressure fuel pump (lpfp) is unable to maintain the required pressure.

Data about the high pressure gasoline pump:

The pressure is now 149728-150182hPa, which should be maintained at 150-200.00hPa in normal mode.

After a duration of 4 seconds with the engine turned off, the atmospheric pressure recorded was 149400.14hPa. (The engine must be turned off for at least 3/4 seconds, with the pressure not dropping below 500hPa)

Real-time EKPS values

Control parameters:

    The designated velocity of the Low Pressure Fuel Pump (LPFP) is between 9146 and 9218 units. One per minute
    The stated supply rate is between 238 and 244 litres per hour. The actual speed is between 8570 and 8692 revolutions per minute.

Voltage and currents:

    The value at terminal 30 is 14.10-14.20 V, which is the power supply voltage.
    The voltage of the fuel pump is 14.00 V, with an optimum value of 7 V at idle. This voltage is the output voltage of the fuel pump.
    The voltage of phase B is 0V. Phase C voltage: 0 volts. Current at the power factor: 9.00-9.10 amperes. FP phase B+C: 0 amperes

Based on this observation, it is evident that the low-pressure fuel pump is receiving an excessively high voltage, indicating that it is operating at a heightened level to sustain the required pressure. This is also apparent in the fluctuation of low pressure measurements.

What are the potential issues?

    Are there any problems with the low-pressure sensor, such as a defective replacement or wiring issues?
    Are there any issues with the LPFP (Low-Pressure Fuel Pump), such as wiring difficulties or defective replacements?
    Are there any leakages or obstructions in the low-pressure fuel system?
    Is there a check valve in the fuel pump?


I would really appreciate any suggestions on my future course of action. The Garage intends to attempt various repairs by replacing components, while my web research has just served to further confuse me and diminish my optimism of being able to solve this issue on my own!

    I own a multimeter and can assess the condition of the components in the fuel system, provided I do further investigation. Additionally, my scan tool should be capable of obtaining satisfactory real-time data from the vehicle. However, I am uncertain about the specific regions that need examination.

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The issue with the 2AAF code on our e91 was resolved by replacing the low pressure sensor located on the fuel piping on the right-hand side of the rocker cover.

I do not believe that is the root cause of the misfire on cylinder 3 problem. I suggest attempting to resolve the issue by exchanging the coil pack with another cylinder and seeing whether the error reoccurs.

The issue with the map thermostat is most likely due to a requirement for a replacement thermostat.

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Expressing gratitude. Indeed, the installation of a new thermostat is necessary. The misfire is intermittent and specifically affects cylinders 3 and 4, making it difficult to identify the cause.

I have already replaced the low fuel pressure sensor as well as the low pressure fuel pump and filter. The code is still present!

What is the most effective way to check whether a sensor is functioning correctly?

When examining fuel pressure, it seems that the low-pressure fuel pump (LPFP) is unable to sustain and retain the necessary pressure, while the fuel pump is using a significant amount of electrical power, indicating that it is likely operating over its normal capacity.

Do you believe that this issue may be attributed to a vacuum leak, a leak or obstruction in the fuel system, or defective wiring? Could it be injectors?

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In such scenario, I would expect a potential problem with the injectors, since the n43 injectors are known to be of subpar quality. Remove the spark plugs and inspect their condition to see whether they are covered with soot. It is advisable to check the items the next day to see whether any of them are also moist.

Did you install an authentic low pressure sensor?

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Indeed, it is an excellent suggestion. I will do this task as I want to replace the spark plugs in the near future.

I installed a robust automotive low-pass fuel system. Although not optimal, my auto start stop feature has resumed functioning following installation.

The long-term fuel trim for bank 1 was measured at 10.90% during an idle scan. Does this reading suggest any specific information?

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Attempt to remove the injectors, reposition the fuel lines, and reinstall the injectors. Do not establish a connection with the power supply. Remove the fuse for the fuel pump and place a layer of dish towel behind the injectors. Next, activate the engine to initiate the pressurisation of the high pressure fuel pump. Then search for the flow of gasoline. Two of my items have a little dispersion issue, and one of them has a small leakage problem, indicating their poor quality. It seems that the issue caused significant damage to my first cat, resulting in a complete blockage of the second cat.

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Thank you, I agree it is a commendable suggestion. I intend to either follow your suggestion or see an injector professional to examine my injectors and fuel system in order to exclude them as potential causes.

When removing injectors, as you have indicated, to inspect for leakage or spray pattern, is there any component that needs replacement before reinstalling them, such as the coupling?

If the issue is connected to the injector, I hope to obtain reasonably inexpensive ones and programme them independently.

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Thank you.

While driving today, I saw error code 2A2D, which pertains to fuel pressure. It is worth noting that error code 2AAF is no longer operational. The freeze frame data indicates that the injected fuel mass is recorded as 0.00 litres per hour, whereas the fuel pressure prior to the fuel supply control valve is measured at 1570.7 millibars.

Additional information:

Oxygen sensors and bank The pre-catalytic converter voltage at idle is between 1.99 and 2.01 volts, indicating a rich mixture.
The oxygen sensor located after the catalytic converter is measuring a voltage of 0.85 volts when the engine is idling.

Based on the observed increase in RPM and the recommended levels, it seems that my MAF sensor is functioning correctly.

Today, the long-term fuel trims for bank 1 were measured at 16.4%, indicating a rich mixture at idle. This value has increased compared to the previous measurement. The short-term fuel trim for bank 1 is reading between 1.6% and 3.1% at idling.

While operating the vehicle and at high engine speeds, both the long term and short term fuel trims decrease dramatically.


The O2 sensors are detecting an excessive amount of fuel in the air-fuel mixture, nevertheless, the long-term fuel trims are still elevated. If the O2 sensors consistently detect these numbers, wouldn't the Long Term Fuel Trim (LTFT) decrease? Can we exclude the possibility of O2 sensors being the cause?

What is the reason for the decrease in Long-Term Fuel Trim (LTFT) and Short-Term Fuel Trim (STFT) values when driving? Is it possible that there is a vacuum leak occurring beyond the MAF sensor?

Does the suspicion of leaky or clogged injectors align with this data?

To ensure accuracy, it is advised to manually check the low-pressure fuel readings with the sensor readings. If the readings are same, the EKPS should be changed. Opinions?

Greatly valued!

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