N53 strange noise, fault codes

March325i · 06-04-2018, 10:00 AM

Hello all,

This is my first post here, so sorry if I did something wrong, but I have no idea, what could be wrong with my car and hope You guys will help me.
Patient: 2007 e91 325i with N53B30 218hp engine.
So everything started less than a year ago, when while cruising at 6th gear I was trying to overtake, pushed accelerator little more and felt, that car is not responding as it should. After a moment reduced power amber light came on as well as hard impact (if I understand that correctly, it was fuel cut-off) and fan started running at full power. After turning engine off and on again everything was working fine. At that moment the only code I got was 29F2 - fuel rail pressure too low. First idea - HPFP.
After that time I learned how to get the car to throw that code again - low rpm, high load (usually 6th gear going uphill at low speed). Since then just to be sure I am not getting bad digits, I replaced both fuel pressure sensors - no luck.
BUT, recently something new started going on. I got faults not just for high pressure, but for low as well. This got me thinking, that HPFP might be fine, but something on the LPFP side might be going down and it just can't keep the pressure when car needs it. And as a result HPFP is getting less fuel than it supposed to so the pressure drops below the limit. If I push the car to the limit, high speed at high RPM, it pulls very well but even with higher RPM it sometimes throws me same faults about rail pressure or both rail and low side pressure.
Today I noticed strange sound coming from the engine bay. Hooked up my laptop with INPA and noticed, that strange sucking/grinding kind of sound appears as the low pressure jumps +/- 100hPa.
So, the question is what is going on? What should I look at? I don't want to believe that my HPFP is going down, I feel that the problem is with either LPFP or pressure regulator/filter at the tank, but at this moment I'm tired of all this parts changing/thinking stuff.
I attached photo of both faults and video of sound as well as INPA screen. You can hear it when I keep my foot just barely touching accelerator.
I hope You guys will have some cool ideas.

https://youtu.be/gQxQ9jD2szA

06-04-2018, 10:00 AM	#1
March325i Registered 0 Rep 1 Posts Drives: 2007 E91 325i N53 Join Date: Jul 2017 Location: Garage iTrader: (0)	N53 strange noise, fault codes Hello all, This is my first post here, so sorry if I did something wrong, but I have no idea, what could be wrong with my car and hope You guys will help me. Patient: 2007 e91 325i with N53B30 218hp engine. So everything started less than a year ago, when while cruising at 6th gear I was trying to overtake, pushed accelerator little more and felt, that car is not responding as it should. After a moment reduced power amber light came on as well as hard impact (if I understand that correctly, it was fuel cut-off) and fan started running at full power. After turning engine off and on again everything was working fine. At that moment the only code I got was 29F2 - fuel rail pressure too low. First idea - HPFP. After that time I learned how to get the car to throw that code again - low rpm, high load (usually 6th gear going uphill at low speed). Since then just to be sure I am not getting bad digits, I replaced both fuel pressure sensors - no luck. BUT, recently something new started going on. I got faults not just for high pressure, but for low as well. This got me thinking, that HPFP might be fine, but something on the LPFP side might be going down and it just can't keep the pressure when car needs it. And as a result HPFP is getting less fuel than it supposed to so the pressure drops below the limit. If I push the car to the limit, high speed at high RPM, it pulls very well but even with higher RPM it sometimes throws me same faults about rail pressure or both rail and low side pressure. Today I noticed strange sound coming from the engine bay. Hooked up my laptop with INPA and noticed, that strange sucking/grinding kind of sound appears as the low pressure jumps +/- 100hPa. So, the question is what is going on? What should I look at? I don't want to believe that my HPFP is going down, I feel that the problem is with either LPFP or pressure regulator/filter at the tank, but at this moment I'm tired of all this parts changing/thinking stuff. I attached photo of both faults and video of sound as well as INPA screen. You can hear it when I keep my foot just barely touching accelerator. I hope You guys will have some cool ideas. https://youtu.be/gQxQ9jD2szA Attached Images
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