[MyCar]

Hi all, need help please.
335i N55 Engine suddenly experiencing the following issue out of the blue

• Yellow Half Engine Malfunction Reduced Power Warning
• When this warning comes on, the engine idles very rough and car stalls
• No check engine light
• No codes thrown. (UPDATE - Pending Code P0087)
• Turning the car off, letting it sit for a while and turning back on seems to resolve the issue temporarily. Including the Yellow Half Engine Malfunction warning going away
• Seems to occur if it's very cold outside
• Seems to occur during idle
• If I put car in reverse, for example when parallel parking, car idles very rough and putters as if it wants to turn off.

I'm confused because there are no codes thrown, and the half engine warning goes away on it's own if I turn the car off and let it rest for a bit.

Could it be HPFP? Pressure Convertor/Boost Solenoid? Vanos Solenoids?

It's a bit of a guessing game with no codes thrown.

Any suggestions or thoughts?

UPDATE:
Pulled the following codes:

• Error Code 2BEE
  0x2BEE High-pressure fuel system, cold start: Pressure too low
  Possible fault causes:
  -Tank Empty
  -Defective rail-pressure sensor
  -Defect in low-pressure system
  -High-pressure pump defective
  
• Error Code 2C01
  0x2C01 High-pressure fuel system, fuel pressure: Minimum pressure undershot
  Possible fault causes:
  -Fuel tank empty
  -Obstruction in fuel filter
  -Fuel pump defective
  -Defective rail-pressure sensor
  -High-pressure pump defective
  
• Error Code 3876
  0x3876 Power management: Central Under-voltage
  

[JessiV909]

Does it throw any codes when the car stalls?

[relative4]

The codes are there. The generic scanner you're using is inadequate to the task. You need a BMW-capable scanner. ISTA, MHD, BimmerGeeks, Foxwell, Launch, Carly.

[TunafishE93]

You will still get code with a regular scanner, only different is the format the code is presented.

My money is on the battery... They get weak when cold, the hint about only happening when cold.. That's just a guess but could be a million other things. Batteries are a good place to start.

Need more info though, does this happen when just starting car? When cars been running warmed up? If you drive car will it happen once you stop?

[relative4]

Originally Posted by TunafishE93

You will still get code with a regular scanner, only different is the format the code is presented.

Inaccurate. Some codes will show up on a generic scanner, some won't. More to the point, no generic scanner will display the full code history available in ISTA.
A bad battery will result in more codes, not fewer.

[MyCar]

Originally Posted by TunafishE93

You will still get code with a regular scanner, only different is the format the code is presented.

My money is on the battery... They get weak when cold, the hint about only happening when cold.. That's just a guess but could be a million other things. Batteries are a good place to start.

Need more info though, does this happen when just starting car? When cars been running warmed up? If you drive car will it happen once you stop?

Hi. I put in a new battery this past summer, and got it coded as well. The battery is good.

When the half engine reduced power malfunction warning comes on I will try scanning for codes. I have been scanning after the warning goes away thinking a code would be stored, so I’ll have to try once the warning is still up.

[relative4]

Originally Posted by MyCar

When the half engine reduced power malfunction warning comes on I will try scanning for codes. I have been scanning after the warning goes away thinking a code would be stored, so I’ll have to try once the warning is still up.

The code is stored after the light turns off, but a generic scanner cannot read it at that point. ISTA can.
When the light is still on, a generic scanner will pull SOME of the potentially available codes. It may not give you the whole story.

[TunafishE93]

I heard of codes you can't read with a normal scanner. The only ones I haven't seen was were "inactive" codes. Every code that has been active that I have seen could be read with both of my scanners. Granted I haven't had to many codes thrown.

It is a bad assumption to say I replaced battery its good. Brand new batteries have been know to be bad. I would at least test the basics...

[Bimmer_Engineer]

Are you using a scanner that is bmw specific or just obdii?

[MyCar]

Originally Posted by Bimmer_Engineer

Are you using a scanner that is bmw specific or just obdii?

I’m using the Torque Pro app, it’s not BMW specific which is probably why I can’t see the codes once the half engine malfunction warning goes away.
Oddly enough today my car is running fine, I expect tonight when it’s cold outside for the issue to return.

[$$$-n-bullets]

Check the throttle actuator. And or reset adaptive values

[MyCar]

Originally Posted by JessiV909

Does it throw any codes when the car stalls?

The yellow Half Engine Malfunction warning came on again, this time I decided to use my generic Torque Pro app to see if it would pull any codes, and sure enough it showed a pending code of P0087.

What could be causing a pending P0087?

[techwhiz]

Originally Posted by MyCar

The yellow Half Engine Malfunction warning came on again, this time I decided to use my generic Torque Pro app to see if it would pull any codes, and sure enough it showed a pending code of P0087.

What could be causing a pending P0087?

Low fuel rail pressure.
It's a generic OBDII code that means fuel rail pressure is too low.
Do you get the fault under load/acceleration?
Sounds like it might be the HPFP.

[MyCar]

Originally Posted by techwhiz

Low fuel rail pressure.
It's a generic OBDII code that means fuel rail pressure is too low.
Do you get the fault under load/acceleration?
Sounds like it might be the HPFP.

Not under any type of unusual heavy load. Probably under 3K RPMs. It’s also happened when I first start car and idle.

So you think it’s the actual HPFP and not just the fuel sensor?

[relative4]

A generic scanner is not the tool for this job. You need ALL the codes.

[TunafishE93]

Error is the same as 2BF5

The diagnostic function monitors the rail
pressure to determine whether it drops too low during operation.

the relative rail pressure
during engine operation is >
40 bar and a mixture fault or
a fuel high-pressure fault is
present at the same time.
Potential problem source(s):
- Defect in wiring harness
between DME and rail-
pressure sensor
- Defective rail-pressure
sensor
- Defect in high-pressure system

So yes high press side issues...

[MyCar]

Originally Posted by TunafishE93

Error is the same as 2BF5

The diagnostic function monitors the rail
pressure to determine whether it drops too low during operation.

the relative rail pressure
during engine operation is >
40 bar and a mixture fault or
a fuel high-pressure fault is
present at the same time.
Potential problem source(s):
- Defect in wiring harness
between DME and rail-
pressure sensor
- Defective rail-pressure
sensor
- Defect in high-pressure system

So yes high press side issues...

Hi Tunafish, can you elaborate on what you think is causing this?

[MyCar]

Originally Posted by Bimmer_Engineer

Are you using a scanner that is bmw specific or just obdii?

I was able to pull the stored codes.

• Error Code 2BEE
  0x2BEE High-pressure fuel system, cold start: Pressure too low
  Possible fault causes:
  -Tank Empty
  -Defective rail-pressure sensor
  -Defect in low-pressure system
  -High-pressure pump defective
  
• Error Code 2C01
  0x2C01 High-pressure fuel system, fuel pressure: Minimum pressure undershot
  Possible fault causes:
  -Fuel tank empty
  -Obstruction in fuel filter
  -Fuel pump defective
  -Defective rail-pressure sensor
  -High-pressure pump defective
  
• Error Code 3876
  0x3876 Power management: Central Under-voltage
  

In addition to the above codes, a standard OBDII code reader pulls pending P0087.

Seems like many possible fault causes. What do you all think?

[relative4]

Obviously, the codes indicate either the sensor or the pump. Your fuel starvation symptoms indicate the pump.

[MyCar]

Originally Posted by relative4

Obviously, the codes indicate either the sensor or the pump. Your fuel starvation symptoms indicate the pump.

lol right, it's one of those. The rail pressure sensor is only like $80-90 bucks, the HPFP is $500-700. I'd hate to buy the HPFP and find out it was just the sensor.

Anyway to narrow down further?

[techwhiz]

Originally Posted by MyCar

lol right, it's one of those. The rail pressure sensor is only like $80-90 bucks, the HPFP is $500-700. I'd hate to buy the HPFP and find out it was just the sensor.

Anyway to narrow down further?

I can tell you the sensor fails at a much lower rate than the pump.
I had 4-5 pumps before 100K miles. The last one lasted 100K+ and I just swapped it out. I have yet to change that sensor. YMMV

[MyCar]

Originally Posted by techwhiz

I can tell you the sensor fails at a much lower rate than the pump.
I had 4-5 pumps before 100K miles. The last one lasted 100K+ and I just swapped it out. I have yet to change that sensor. YMMV

What’s strange is my car never has long cranks, starts up immediately! What’s even more strange is that for the past few days car has been running fine, no rough idle, no stalls, no engine malfunction warning.

I’m confused.