VTT N54 HPFP Information/Disassembly/Upgrade Post

Albrigtsen

New Member
Aug 20, 2017
4
2
0
Does someone know if or how much more force the design of vacuum pump and drivetrain (oil pump) can safely support? In other words, is it possible to redesign a pump with higher capacity still driven by the stock drivetrain? My first thought of an upgrade is to get rid of the bellows and just use three big pistons instead. A slightly increase in stroke should also be possible with a better swash plate and piston design. As I see it this stock design is just a way to not have a dynamic seal between the cylinder “fuel side” and the lubrication side. A big piston with dynamic seal design would have some fuel contamination to the lubrication side but this could be solved with replacing the oil now and then. An oil fill and drain port could be added and with increasing the volume of oil the shift interval should not be to often…

I’m not an expert on this so I’m not sure if this is doable or a good idea at all?

Also sorry for my spelling, I still trying to figure out why not the rest of the world speaks and writes Norwegian… :smile: (Irony for those who don’t have humor)
 

9krpmrx8

Sergeant
Nov 5, 2016
468
250
0
San Antonio, Texas
Bump. On the cheaper rebuilt units, does anyone have any idea what they are rebuilding? My original lasted 75k on my 2011 E90, I replaced it with a cheap OSIAS one and it lasted about 35k or so before it just died from one day to the next with no warning, and then I bucked out for an OEM one and now it is giving up the ghost after a year. I am just curious what the failure mode is but I have not torn either one apart.
 

Jern54

Corporal
Oct 18, 2019
159
77
0
Netherlands
Ride
E91 N54 335i
The control valve is the weakest link in this assembly. I work a lot with hydraulic piston pumps and they last pretty long. The control valve has rubber sealings on the shaft which tends to leak after X miles or years.
 
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IQraceworks

Specialist
Jul 7, 2020
94
34
0
Missouri
Ride
07' BMW 335i
The control valve is the weakest link in this assembly. I work a lot with hydraulic piston pumps and they last pretty long. The control valve has rubber sealings on the shaft which tends to leak after X miles or years.

I wonder if that could be what's going on with mine. When I start to easily roll on the throttle at low boost, the HPFP just takes a dump down to 200-ish psi and the car does the 29DC Injector Cutoff thing. Both banks of fuel trims max out at 34% trying to keep the cylinders from going lean. I'm assuming that this is an HPFP issue.....right? As soon as the motor falls on it's face and cuts the injectors off and I let off the gas, the HPFP shoots back up to 2,800psi. Could this bad a problem with the fuel control valve? As far as I know it's the original 07' HPFP with 100K miles on it.

 

Jern54

Corporal
Oct 18, 2019
159
77
0
Netherlands
Ride
E91 N54 335i
I wonder if that could be what's going on with mine. When I start to easily roll on the throttle at low boost, the HPFP just takes a dump down to 200-ish psi and the car does the 29DC Injector Cutoff thing. Both banks of fuel trims max out at 34% trying to keep the cylinders from going lean. I'm assuming that this is an HPFP issue.....right? As soon as the motor falls on it's face and cuts the injectors off and I let off the gas, the HPFP shoots back up to 2,800psi. Could this bad a problem with the fuel control valve? As far as I know it's the original 07' HPFP with 100K miles on it.

Yeah, seems like your HPFP has died. LPFP is bouncy as well but that doesn't caused the HPFP crash like that.
 

IQraceworks

Specialist
Jul 7, 2020
94
34
0
Missouri
Ride
07' BMW 335i
Yeah....I've noticed that the LPFP pressures are not smooth....it's been that way ever since I installed that Walbro 450. I always just thought that the EKP just wasn't that great at controlling the bigger than stock pump? I searched online and it sounds like a pretty common issue....that doesn't really hurt anything.
 

IQraceworks

Specialist
Jul 7, 2020
94
34
0
Missouri
Ride
07' BMW 335i
Well....I gave it one more shot before I ordered a new HPFP. First, I checked all the plugs after the car sat all day...all dry and look fine (no leaky injectors). Then I hooked up MHD, got a log running, and fired up the car.

This time the HPFP never got above 50psi...the motor sputtered and coughed as it attempted to idle. After doing that for around 10 seconds, the HPFP came to life and the pressure sprung up to around 2,600psi and the motor started to idle normal.

At this point....I'm 110% sure it's a HPFP problem. I think something is jacked up with the built in fuel pressure regulator. I'm going to order a new one off of FCP Euro tonight, along with a new rail pressure sensor.

I will report back after the parts show up and I get to take the car for a test drive. 👍