[clor]

Hi guys,

I have a 2014 435iX F32 and I got a Drivetrain Malfunction for the code: 11A002 (Fuel Pressure Below Target) and 11AC02 (high-pressure fuel system, cold start: pressure too low)

Mods:
Aftermarket Chargepipe
JB4
CL Downpipe.

I can't tell if I need a new HPFP for the gas tank or the one that is inline with the direct injection in the engine bay. It starts up fine, I will get the error code as I'm driving off, it will put me in "limp mode". I try to erase it (Jb4) while I'm driving as well and it just comes back on.

Could anyone steer me in the right direction? I'm really hoping it's the one in my gas tank. Or if anyone knows how I can tell the difference of the issue between the HPFP in my gas tank and the HPFP inline with the direct injection inside the engine bay.


Kind regards.

[MineralF30]

Originally Posted by clor

Hi guys,

I have a 2014 435iX F32 and I got a Drivetrain Malfunction for the code: 11A002 (Fuel Pressure Below Target) and 11AC02 (high-pressure fuel system, cold start: pressure too low)

Mods:
Aftermarket Chargepipe
JB4
CL Downpipe.

I can't tell if I need a new HPFP for the gas tank or the one that is inline with the direct injection in the engine bay. It starts up fine, I will get the error code as I'm driving off, it will put me in "limp mode". I try to erase it (Jb4) while I'm driving as well and it just comes back on.

Could anyone steer me in the right direction? I'm really hoping it's the one in my gas tank. Or if anyone knows how I can tell the difference of the issue between the HPFP in my gas tank and the HPFP inline with the direct injection inside the engine bay.


Kind regards.

Basically, the pump in the tank is the LPFP (low pressure fuel pump) and the one in the engine bay is the HPFP.

I had similar codes relating to fuel pressure for months and it ended up being my Walbro 450 LPFP. I did replace my HPFP before that and it didn't fix it, so I'd say replace the pump in the tank first and see if that fixes it.

[clor]

Originally Posted by MineralF30

Basically, the pump in the tank is the LPFP (low pressure fuel pump) and the one in the engine bay is the HPFP.

I had similar codes relating to fuel pressure for months and it ended up being my Walbro 450 LPFP. I did replace my HPFP before that and it didn't fix it, so I'd say replace the pump in the tank first and see if that fixes it.

Thanks mate! I have a JB4 and logged it. I'm not seeing anything on my LPFP... so I am assuming that is the issue... I'm comparing data with what I've logged in the past and I don't see any values in the LPFP section, it's "0"... wish that JB4 would explain the definitions and number logs a bit more clear.


Thanks again!

[clor]

Originally Posted by MineralF30

Basically, the pump in the tank is the LPFP (low pressure fuel pump) and the one in the engine bay is the HPFP.

I had similar codes relating to fuel pressure for months and it ended up being my Walbro 450 LPFP. I did replace my HPFP before that and it didn't fix it, so I'd say replace the pump in the tank first and see if that fixes it.

Well I logged my car with the JB4 and for my Low Pressure Pump, I'm basically reading nothing. So I am assuming nothing or not enough is getting delivered to the High Pressure Pump.

According to JB4,
FP L: Fuel pressure, low system. Pressure is read on the left hand scale X 10. Otherwise known as the in tank low pressure fuel pump. This value typically ranges from 55-70psi. If dropping below 50psi it indicates a problem with your low fuel pressure pump. Most often that problem is it needs to be augmented with an inline pump to keep up with the higher fuel demands required by ethanol usage.
　
FP H: Fuel pressure, high system. Otherwise known as the high pressure pump. Note all N54 include this and other platforms can only log this if also equipped with the flex fuel connector. This value represents the voltage of the high pressure 0-5V sensor, where a value of 20 is 5v. Each unit of measure is roughly equal to 150psi. Typical values at full throttle are 10-14, or 1500 to 2100psi. Values of less than 900psi as full throttle indicate a fuel delivery problem and the JB4 will failsafe at 700psi at full throttle. Note when not at full throttle a typical value is 5 or 750psi.

[MineralF30]

Originally Posted by clor

Well I logged my car with the JB4 and for my Low Pressure Pump, I'm basically reading nothing. So I am assuming nothing or not enough is getting delivered to the High Pressure Pump.

According to JB4,
FP L: Fuel pressure, low system. Pressure is read on the left hand scale X 10. Otherwise known as the in tank low pressure fuel pump. This value typically ranges from 55-70psi. If dropping below 50psi it indicates a problem with your low fuel pressure pump. Most often that problem is it needs to be augmented with an inline pump to keep up with the higher fuel demands required by ethanol usage.
　
FP H: Fuel pressure, high system. Otherwise known as the high pressure pump. Note all N54 include this and other platforms can only log this if also equipped with the flex fuel connector. This value represents the voltage of the high pressure 0-5V sensor, where a value of 20 is 5v. Each unit of measure is roughly equal to 150psi. Typical values at full throttle are 10-14, or 1500 to 2100psi. Values of less than 900psi as full throttle indicate a fuel delivery problem and the JB4 will failsafe at 700psi at full throttle. Note when not at full throttle a typical value is 5 or 750psi.

Yeah I would start with replacing the LPFP. Usually when you're getting a cold start code it is because the lpfp isn't sending enough fuel up to the engine or something in that nature.

[clor]

Originally Posted by MineralF30

Yeah I would start with replacing the LPFP. Usually when you're getting a cold start code it is because the lpfp isn't sending enough fuel up to the engine or something in that nature.

Thanks, I just want to narrow it down as scientifically as possible. I've narrowed it down that for N55's, the JB4 won't read the low fuel pump pressure. But I am able to read the high fuel pump pressure. Which it indeed did look good, until it goes into limp mode. So I am narrowing it down that it's not getting enough fuel deliver from the low fuel pump pressure.

On the flip side, that's better than replacing the high fuel pump because it looks to be a pain in the ass to do. On the other hand, I'm going to have to find something to unscrew that lock that covers the low pressure pump, since it uses this fancy tool. Maybe I can make something from home to undo the cover.

[MineralF30]

Originally Posted by clor

Thanks, I just want to narrow it down as scientifically as possible. I've narrowed it down that for N55's, the JB4 won't read the low fuel pump pressure. But I am able to read the high fuel pump pressure. Which it indeed did look good, until it goes into limp mode. So I am narrowing it down that it's not getting enough fuel deliver from the low fuel pump pressure.

On the flip side, that's better than replacing the high fuel pump because it looks to be a pain in the ass to do. On the other hand, I'm going to have to find something to unscrew that lock that covers the low pressure pump, since it uses this fancy tool. Maybe I can make something from home to undo the cover.

I would recommend buying the lock ring tool from Spool Performance. It's pretty cheap, I think I bought mine for $20 but it's worth it.

[clor]

Originally Posted by MineralF30

I would recommend buying the lock ring tool from Spool Performance. It's pretty cheap, I think I bought mine for $20 but it's worth it.

Yeah, you're right. Going to cost me as much in shipping as it will in buying it lol.

It's on sale for $15 and cost me $12 to ship it lmao. Maybe I can find something in town here..... would hate to half fast this lol.

[MineralF30]

Originally Posted by clor

Yeah, you're right. Going to cost me as much in shipping as it will in buying it lol.

It's on sale for $15 and cost me $12 to ship it lmao. Maybe I can find something in town here..... would hate to half fast this lol.

Good luck man. I tried searching but that was the best option, the shipping does suck but I still don't regret it lol.

[T_H_O_M_A_S]

JB4 will always show zero for the FPL because
your car's model doesnt have a LPF sensor . It can only read the high pressure value from the sensor at the end of your fuel rail .
if im correct , only early n55's with the older style N54hpfp do have a LPF sensor
but that wont solve your problem .

get a decent mechanic to look at it before replacing parts your not sure about .

[clor]

Originally Posted by T_H_O_M_A_S

JB4 will always show zero for the FPL because
your car's model doesnt have a LPF sensor . It can only read the high pressure value from the sensor at the end of your fuel rail .
if im correct , only early n55's with the older style N54hpfp do have a LPF sensor
but that wont solve your problem .

get a decent mechanic to look at it before replacing parts your not sure about .

Thanks, I ran logs and I believe it's the LPF. I basically just ordered the newest replacement model for it. It doesn't appear to be any electrical/electronic cabling issues. At the time being, I just ordered two-step colder plugs too. Might as well.. my car is at 75k and I haven't even changed it yet since I bought it from 30k lol. So it's about that time. But yes you're right, I can't see my LPF, but I can see the HPF. It idles at 7-8 and when the drivetrain malfunction comes on it sets at 2. I'm thinking it doesn't receive enough low pressure fuel. I haven't gotten any hard codes for HPF symptoms yet.

[kjacobidj@gmail.com]

I had the same error plus a slew of others. I just removed the JB4 and everything cleared up.

[Ajax915]

Originally Posted by clor

Hi guys,

I have a 2014 435iX F32 and I got a Drivetrain Malfunction for the code: 11A002 (Fuel Pressure Below Target) and 11AC02 (high-pressure fuel system, cold start: pressure too low)

Mods:
Aftermarket Chargepipe
JB4
CL Downpipe.

I can't tell if I need a new HPFP for the gas tank or the one that is inline with the direct injection in the engine bay. It starts up fine, I will get the error code as I'm driving off, it will put me in "limp mode". I try to erase it (Jb4) while I'm driving as well and it just comes back on.

Could anyone steer me in the right direction? I'm really hoping it's the one in my gas tank. Or if anyone knows how I can tell the difference of the issue between the HPFP in my gas tank and the HPFP inline with the direct injection inside the engine bay.


Kind regards.

Was it the lpfp ?