Dear customer, this type of failures can happen with time and travel of the car, identify them accurately is a bit complicated from my point of view becasue i am not with the vehicle, but I will proceed to indicate the areas that you should check in your vehicle, so you will understand what is happening and we can get to the solution of your problem.
A diesel vehicle works with certain conditions that we must have in full operation to allow the vehicle works well
A diesel vehicle requires the following 4 factors:
1) good compression in the cylinders
2) a high pressure in the fuel injection system
3) a good air intake
4) and a high temperature in the cylinders
First of all, the compression is rule out in your case, because when there is a loss of compression in the cylinders the vehicle constantly fails more in the Diesel, because the compression together with the injector makes the combustion, but do not worry because this happens when there is internal damage to the engine but it is not your case.
Second, if you can have problems in the fuel injection pressure, this pressure is given by the fuel pump, but there are certain factors that can affect this pressure, such as lack of maintenance, dirt in the tank, filters covered or dirty or injectors with a defect cause these problems as you describe me, when example your vehicle is in good working order until the pump becomes clogged with dirt or heats up more than usual causing you to have the problems of ignition as you present, also a fuel leak in the rail causes this problem, this may be due to an internal problem in the pressure seals, or when a injector is direct by this pressure escapes causing these problems.
This is solvable by performing a maintenance to the fuel rail and its components (including injectors, pumps, etc ...) also, replacing its filters.
Then as I mentioned a good air intake is necessary for a good operation of the vehicle, when we present problems in the supercharger air supply or in some sensor of the throttle body or air flow meter, because these sensors are responsible for regulating the acceleration of the vehicle, to know the good or bad operation of these is necessary to perform a computerized diagnosis of the vehicle to know the parameters on live data.
At last a good temperature, if the faults occur in very cold climates, it is good to analyze the cooling system and thermostat of the vehicle, if the engine cools more than the account causes these problems, one of the factors for a good ignition is that the engine must preheat the fuel before turning on.
The diesel is thicker or denser, this work is done by the glow plugs, when you apply Easy star you take advantage of the first combustion becauseit is more volatile.
As you will see dear customer, there are several factors to analyze, I think it is prudent that the first thing you do is a good automotive diagnosis with a scanner with the BMW X5 software according to the parameters obtained by the technician to proceed, the problem is that the RAC and the alternative garages do not have the software of the brand, thus causing the values are not correct or accurate.
As for a relay, this is located in the fuse box and relays under the engine compartment, when you remove the cover you get a legend, there you locate it.
Have you understood me dear customer?
Dear Customer, my goal is to give you the best advice I can and I hope that I've helped today.
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