Losing fuel pressure and my sanity :(

Dandy.93

Lurker
Nov 24, 2020
10
0
0
Hey there lads. Never thought I would have to post on forums for help but here I am. I have a 2008 335i (N54).

So recently my car has been feeling horrible and having symptoms of HPFP failure :( :
1. Rough cold start
2. Feels like misfires when under mild acceleration.
3. If I accelerate for more than a couple of seconds the engine shakes and violently jerks the car, cutting the turbos out and shutting off the HPFP. Rail pressure drops and matches the low-pressure fuel pump (85 psi). This causes the car to blast the radiator fan to full power and go into limp mode. I can temporarily solve this by shutting the car off and on again.

Oh and another thing.
4. Odd high pitched siren/whistle sound when under acceleration and metal clank noise? But no wastegate rattle. Might be a separate issue?

Codes :
29f1 - Fuel pressure plausibility
29cf- Misfire (probably caused by the drop in fuel pressure)

Since I know it's pretty common for our HPFP's to fail, I ended up buying one off FCP euro for $780 and installed it.
BUT unfortunately no luck. The car still violently jerks and shuts off the HPFP and I don't know why. I'm losing my damn mind with the car and I've only had it for a year. 😡

I managed to make a quick log after installing the new pump showing the fuel pressure dropping and skyrocketing my afr:

And this is what INPA showed in error memory:
Desktop Screenshot 2020.11.22 - 14.53.11.86 (2).png



It appears that the P-Code assigned with the 29f1 code is P3284. Definition: Fuel pressure control Bank 1 calculation of adaptive fuel volume implausible.

I'm fairly new to the car scene so any help would be greatly appreciated!. 🙂
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
Ride
2009 e93 335i
Hey there lads. Never thought I would have to post on forums for help but here I am. I have a 2008 335i (N54).

So recently my car has been feeling horrible and having symptoms of HPFP failure :( :
1. Rough cold start
2. Feels like misfires when under mild acceleration.
3. If I accelerate for more than a couple of seconds the engine shakes and violently jerks the car, cutting the turbos out and shutting off the HPFP. Rail pressure drops and matches the low-pressure fuel pump (85 psi). This causes the car to blast the radiator fan to full power and go into limp mode. I can temporarily solve this by shutting the car off and on again.

Oh and another thing.
4. Odd high pitched siren/whistle sound when under acceleration and metal clank noise? But no wastegate rattle. Might be a separate issue?

Codes :
29f1 - Fuel pressure plausibility
29cf- Misfire (probably caused by the drop in fuel pressure)

Since I know it's pretty common for our HPFP's to fail, I ended up buying one off FCP euro for $780 and installed it.
BUT unfortunately no luck. The car still violently jerks and shuts off the HPFP and I don't know why. I'm losing my damn mind with the car and I've only had it for a year. 😡

I managed to make a quick log after installing the new pump showing the fuel pressure dropping and skyrocketing my afr:

And this is what INPA showed in error memory:
View attachment 46528


It appears that the P-Code assigned with the 29f1 code is P3284. Definition: Fuel pressure control Bank 1 calculation of adaptive fuel volume implausible.

I'm fairly new to the car scene so any help would be greatly appreciated!. 🙂
What's the condition of the O2 sensors like ?
 
  • Like
Reactions: Dandy.93

Dandy.93

Lurker
Nov 24, 2020
10
0
0
What's the condition of the O2 sensors like ?
Thanks for the quick reply 🙂 I was getting post-cat codes so I replaced both post-cat o2 sensors earlier this year. However, I have not looked at my pre-cat sensors. What is something I should look for when monitoring them?
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
Ride
2009 e93 335i
If there is something wrong with the o2s you typically will see afrs in each bank vary quite a bit . Also not sure what the condition of your lpfp is
 

Dandy.93

Lurker
Nov 24, 2020
10
0
0
If there is something wrong with the o2s you typically will see afrs in each bank vary quite a bit . Also not sure what the condition of your lpfp is

I think the lambda bank 1 and bank 2 AFR values are somewhat similar. Though rather lean even before the HPFP shuts off around 14.1-16.0. After the hpfp crashes, afr's reach 200+ :oops:. In the log I posted the LPFP stays pretty evenly around 72 psi until the rail pressure starts to fluctuate. Even then the lpfp stays on when the HPFP crashes and stays around 85 psi.
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
Ride
2009 e93 335i
And then you start to missfire at idle? Have you replaced the fuel pressure sensor on the back of the fuel rail?
 
  • Like
Reactions: Dandy.93

PFS

Corporal
Premium Vendor
Nov 19, 2018
167
208
0
Ride
335i
Looks like injectors are not well.

Off throttle it's normal for AF to read 234. If it takes a long time to get up there, or doesn't quite reach that, it's normally leaking injectors.
 

Dandy.93

Lurker
Nov 24, 2020
10
0
0
And then you start to misfire at idle? Have you replaced the fuel pressure sensor on the back of the fuel rail?
The misfire feeling only happens when moving as early as 1500 rpm. It happens right when the car starts jerking really bad and the HPFP is about to crash. I'm thinking it's probably a misfire due to loss in fuel pressure? Sometimes in idle the car will suddenly shake and lose rpm but it fixes itself and doesn't make a code.
I have not yet replaced the fuel rail sensor. Though it's probably the first thing I should replace since its the cheapest of my options. It looks pretty old from the wear of the barcode. I'll order it right now for safe measure.
IMG_1926.jpg
IMG_1927.jpg
 

Dandy.93

Lurker
Nov 24, 2020
10
0
0
Looks like injectors are not well.

Off throttle it's normal for AF to read 234. If it takes a long time to get up there, or doesn't quite reach that, it's normally leaking injectors.
I was also thinking it might be injectors. 🤔 Would leaking injectors cause the HPFP to shut off? Maybe an injector gets stuck open and the dme stops the hpfp? They are all index 11's. My afr's don't usually reach 234 until the HPFP crashes. Then it stays around 200+ until I shut the car off and on again. Isn't that dangerously lean? I forgot to mention the cars an auto.
 

PFS

Corporal
Premium Vendor
Nov 19, 2018
167
208
0
Ride
335i
When coasting it's normal to see 234, if you're sitting there idling and it's 200+ something isn't right. Primary o2 sensors and/or injectors. Yes DME stops the fun when it suspects something weird is going on.
 
  • Like
Reactions: Dandy.93

PFS

Corporal
Premium Vendor
Nov 19, 2018
167
208
0
Ride
335i
I haven't seen a fuel rail sensor go bad. I'm sure they do, but I've never seen it. I'd do other troubleshooting first.
 
  • Like
Reactions: Dandy.93

Dandy.93

Lurker
Nov 24, 2020
10
0
0
I haven't seen a fuel rail sensor go bad. I'm sure they do, but I've never seen it. I'd do other troubleshooting first.
When coasting it's normal to see 234, if you're sitting there idling and it's 200+ something isn't right. Primary o2 sensors and/or injectors. Yes DME stops the fun when it suspects something weird is going on.

I haven't seen one go bad either, there are almost no threads about it. But I don't know what other troubleshooting to do. I don't think you can troubleshoot injectors besides checking spark plugs and they appear fine. And yeah the car will idle at 200+ afr with 85 psi rail pressure. Regarding the o2 sensors, correct me if I'm wrong, when you start the car cold and you immediately start driving, it shouldn't be reading from the o2 sensors because it would be open-loop correct? (Unless it switches with throttle position, I'm not sure). It would stay open loop until o2 sensors warm-up and then go closed loop. So it wouldn't be reliant on the o2 sensors at that moment. And thus if the o2 sensors were the issue the car wouldn't lose pressure and DME shouldn't deactivate the HPFP until the o2 sensors warmed up and went closed loop. Im probably not making any sense but I'm interested in what you think.
 

Sammy_0559

New Member
Dec 5, 2016
2
5
0
Dallas TX
Do the low pressure fuel sensor, I remember a similar problem a few years ago (didn't throw a code either IIRC) and it ended up being that. Also never seen a Rail sensor go bad tbh
 
  • Like
Reactions: Dandy.93 and PFS

Dandy.93

Lurker
Nov 24, 2020
10
0
0
Do the low pressure fuel sensor, I remember a similar problem a few years ago (didn't throw a code either IIRC) and it ended up being that. Also never seen a Rail sensor go bad tbh
Thank you for the reply 🙂 . I will definitely replace the Low-pressure fuel sensor now before doing anything major. I will let you guys know how it goes.
 

RuskiRacer

Sergeant
Jul 17, 2019
429
157
0
Ride
2009 e93 335i
I had the rail pressure sensor go bad on my mom's e chassis n55 and it was nearly undrivable that is the only reason why I recommended looking into it. I agree it's more common for the lpfp sensor to go out. It just seems wierd how it's reading low pressure fuel pressure still because the ones I've seen go out stop reading
 

TheFixer

Corporal
Aug 16, 2020
240
127
0
Tennessee
Ride
2008 535i, my wife
Good luck sorting your issue. These cars don't make finding the issues easy despite all the codes they give to let you know what's wrong.

My fuel filter nipple cracked on mine two weeks ago. That gave me low fuel pressure codes. A lot easier to find being the smell of gasoline permeated through the inside of the car.
 

Kennejp

New Member
Jul 7, 2017
8
8
0
Ride
07 e92 335i , 08 135i
Id assume that you have a leaking injector thats causing your rough idle, misfire and its pulling your hpfp down.
 
  • Like
Reactions: Dandy.93

Dandy.93

Lurker
Nov 24, 2020
10
0
0
Well, quick update. I ordered and replaced both the high-pressure rail sensor and the updated low-pressure sensor. Nothing. :( Now I'm getting 2AAF Fuel pump: Plausibility and the original 29F1 fuel pressure: plausibility.
Car still jerks, showing erratic rail pressure, misfires randomly, fan on max, pulling down my hpfp. @Kennejp I think it might be the injector as well since now there is a slight smell of gas on cold start only. Thank you for your reply. Really bummed about it since they are index 11 injectors with about 20,000 miles.

Though before I try to replace all the injectors. One thing I can't seem to figure out is the sound it makes when it starts failing. There's a high pitched sound and rattlesnake sound. I can't replicate the sound by revving it either, like a traditional wastegate rattle. There's zero wastegate rattle when revving it. I mentioned it in the original post but brushed it off thinking it was not relevant to the issue but now I'm realizing it is. The electronic whine and metal clanking sound always happen when you continue accelerating while the car is jerking (usually I would let off after surging). This time around I went ahead and recorded it. Hopefully, you guys can hear it. I know in the video it sounds like an air leak but sometimes that whistle will hold for around 5-10 seconds without changing frequency or amplitude (even while letting off) then go away. So I'm thinking it may be electronic. It sounds like it's coming from the engine bay and not near the epkm or low-pressure pump.



Here's a log after the sensors.

I'm just tired.
Cheers,
 
Last edited:

Dandy.93

Lurker
Nov 24, 2020
10
0
0
Good luck sorting your issue. These cars don't make finding the issues easy despite all the codes they give to let you know what's wrong.

My fuel filter nipple cracked on mine two weeks ago. That gave me low fuel pressure codes. A lot easier to find being the smell of gasoline permeated through the inside of the car.

I just started getting a slight smell of fuel on cold starts. I should probably check the filter. Where is the fuel filter located? Is it under the car after the fuel regulator? Thanks.
 

b4llistic

Corporal
Nov 22, 2018
119
90
0
Ride
BMW N54
EDIT: Thanks your finding and reading my post. Unfortunately, Spoolstreet is no longer a neutral platform where we can have honest discussions on subjects and products freely.
For this reason I have deleted all information I posted on the forums.
 
Last edited: