[masterstone]

Hey guys,

I can generally find my way to a solution, but this one has me puzzled.

I have cross-referenced a few posts already but something isn't adding up:

https://www.e90post.com/forums/showt...highlight=hpfp
https://www.e90post.com/forums/showt...highlight=hpfp
https://www.e90post.com/forums/showt...highlight=hpfp


What happened -

A little spirited jaunt home on the highway, and after changing gears and mashing the pedal, I think I felt a pop, or just the sudden loss of power. I first thought of when I blew the stock charge pipe up.

I quickly checked for codes on the JB4 app, and nothing. No SES at all, yet there is clearly an issue. Under lets say 40% pedal, the car continued to run fine, only past that was emptiness.

Back to the JB4 app, I can see I'm getting boost build up, and can feel it a bit. I look down, horrified, my HPFP is at 2 psi, when usually it's 5 or greater when in use.

Back to the pedal, past 40% and the HPFP isn't moving at all.....great. I was close to home so got her back there. I did notice while pulling in, the electric fan was on seemingly full blast, and my engine temp was a bit below running temp. That doesn't usually happen


Time for a fuel related side bar - I replaced my original HPFP 11,000km ago, complete genuine OEM with rail sensor, low pressure sensor, gaskets, etc.
Most recently I upgraded my injectors from 9 to 12s, new, Genuine OEM.
Only other fuel item I've done is a fuel it stage 1 inline. That was long before my HPFP replacement.

Fast forward to today, I go down to investigate. According to many people, and my previous HPFP experience, cold starts will tell the truth..... I'm getting full 12-13 psi on cold start. No codes, no lights.

I look under the hood, no fuel leaks along any connections, no popped off charge pipes, absolutely nothing that I can visually see.

Time for INPA, as one member said with out it you're essentially blind. From the other thread, I now think it could be the fuel pump control unit, or possibly the regulator in the tank.

INPA shows fuel pump activation 1 at idle is 53.1% and scales up when the pedal is pushed. Seems normal.
Fuel control valve sits around 50,000 hPa at idle, seems to build up when the petal is pushed as well.

For S&G I look at everything else. O2 sensors, vanos, injector values, boost solenoids, hell even water pump and alternator voltage output.

Further to the above, is it entirely possible for a random thing like this to occur? I know with typical computer systems turning it off and on fixes a slew of things.... but I feel incorrect in thinking that can happen with a BMW.

Now what? I don't exactly want to drive it to recreate the circumstances if I don't have to.

Any insight would be greatly appreciated, and thanks for your time.

[Rule1977]

Originally Posted by masterstone

Hey guys,

I can generally find my way to a solution, but this one has me puzzled.

I have cross-referenced a few posts already but something isn't adding up:

https://www.e90post.com/forums/showt...highlight=hpfp
https://www.e90post.com/forums/showt...highlight=hpfp
https://www.e90post.com/forums/showt...highlight=hpfp


What happened -

A little spirited jaunt home on the highway, and after changing gears and mashing the pedal, I think I felt a pop, or just the sudden loss of power. I first thought of when I blew the stock charge pipe up.

I quickly checked for codes on the JB4 app, and nothing. No SES at all, yet there is clearly an issue. Under lets say 40% pedal, the car continued to run fine, only past that was emptiness.

Back to the JB4 app, I can see I'm getting boost build up, and can feel it a bit. I look down, horrified, my HPFP is at 2 psi, when usually it's 5 or greater when in use.

Back to the pedal, past 40% and the HPFP isn't moving at all.....great. I was close to home so got her back there. I did notice while pulling in, the electric fan was on seemingly full blast, and my engine temp was a bit below running temp. That doesn't usually happen


Time for a fuel related side bar - I replaced my original HPFP 11,000km ago, complete genuine OEM with rail sensor, low pressure sensor, gaskets, etc.
Most recently I upgraded my injectors from 9 to 12s, new, Genuine OEM.
Only other fuel item I've done is a fuel it stage 1 inline. That was long before my HPFP replacement.

Fast forward to today, I go down to investigate. According to many people, and my previous HPFP experience, cold starts will tell the truth..... I'm getting full 12-13 psi on cold start. No codes, no lights.

I look under the hood, no fuel leaks along any connections, no popped off charge pipes, absolutely nothing that I can visually see.

Time for INPA, as one member said with out it you're essentially blind. From the other thread, I now think it could be the fuel pump control unit, or possibly the regulator in the tank.

INPA shows fuel pump activation 1 at idle is 53.1% and scales up when the pedal is pushed. Seems normal.
Fuel control valve sits around 50,000 hPa at idle, seems to build up when the petal is pushed as well.

For S&G I look at everything else. O2 sensors, vanos, injector values, boost solenoids, hell even water pump and alternator voltage output.

Further to the above, is it entirely possible for a random thing like this to occur? I know with typical computer systems turning it off and on fixes a slew of things.... but I feel incorrect in thinking that can happen with a BMW.

Now what? I don't exactly want to drive it to recreate the circumstances if I don't have to.

Any insight would be greatly appreciated, and thanks for your time.

What firmware is your JB4 on?