[AmuroRay]

Guys, I’m getting a nasty cut out on pump fuel - it started with my JB4 MAP5 a few weeks ago. I didn’t use the logging capability at the time, so I didn’t know what happened, but it was like hitting a flat spot while at WOT.

I thought it was because I was aggressive, doing multiple runs in a quick succession at the drag strip, as it never happened before or afterwards.

Fast forward to this week, I get an amazing tune from StageFP, which is head and shoulders above anything I had with the JB4. But then I ran into an issue - the car cut out pretty violently At WOT, setting of the CEL for misfires.

Checking the logs, the car’s fuel pressure dropped off hard. I sent the log to Bob, and he backed off the tune. The new one feels comparable to the JB4 in terms of power, but smoother.

I did a few runs on this map, and all seemed fine, but then the issue reared it head again. This time, I noted that the fuel gauge was just under 1/4 tank, and I got a log to capture it.

It’s never happened on the stock tune, but it happening more frequently now, even on a less aggressive tune. Any way to test the fuel pump itself? I have no plans for PS2 turbos, and port fuel injection - I just want my car to work. What can/should I do?


Edit: Logs

https://datazap.me/u/amuroray/stage-...og=0&data=3-17

https://datazap.me/u/amuroray/stage-...og=0&data=3-17

[Pray for Mojo]

These cars seem to have issues with the fuel pickup below 1/3 of a tank.

[AmuroRay]

Originally Posted by Pray for Mojo

These cars seem to have issues with the fuel pickup below 1/3 of a tank.

You think that was it? Any options on how to check the LPFP?

[bmwchue]

are you on stock fuel pump or upgraded?

[Pray for Mojo]

I wouldn't worry about the LPFP and there's no reason to get an upgraded one unless you're going port injection. Run it hard at a full tank and see if the issue happens again.

[AmuroRay]

Originally Posted by bmwchue

are you on stock fuel pump or upgraded?

Stock pump - but I’m think may be going

[AmuroRay]

I’ll refash to an aggressive map, add more gas until 3/4 a tank and log for you.

[n55david]

Originally Posted by Pray for Mojo

These cars seem to have issues with the fuel pickup below 1/3 of a tank.

Ive never had an issue

[Pray for Mojo]

335 has a different fuel tank than the M235i. People have had issues on track days with these cars going into fuel starvation at low fuel level. I haven't had the problem myself, but I usually avoid beating on the car when it's below 1/3 tank to avoid it.

[AmuroRay]

How do I post logs? Found it

https://datazap.me/u/amuroray/stage-...og=0&data=3-17

https://datazap.me/u/amuroray/stage-...og=0&data=3-17

[AmuroRay]

Originally Posted by AmuroRay

How do I post logs? Found it

https://datazap.me/u/amuroray/stage-...og=0&data=3-17

https://datazap.me/u/amuroray/stage-...og=0&data=3-17

Anyone?

[JaredG_F30]

Yeah man your HPFP takes a shit on both those logs. In the first log, it craps out at 4700rpm, dropping down to 1490psi when 2890psi is requested. The second log you take a big hit at 6197rpm, pressure dives to 1397psi when 2899psi is requested. You either need a new or upgraded HPFP or reduce the boost target. Is this a 93 octane tune or ethanol mix?

[AmuroRay]

Originally Posted by JaredG_F30

Yeah man your HPFP takes a shit on both those logs. In the first log, it craps out at 4700rpm, dropping down to 1490psi when 2890psi is requested. The second log you take a big hit at 6197rpm, pressure dives to 1397psi when 2899psi is requested. You either need a new or upgraded HPFP or reduce the boost target. Is this a 93 octane tune or ethanol mix?

First - thank you for taking a look!
It’s a 93 octane tune - do you think that I’m in need of a HPFP or a LPFP?

[JaredG_F30]

Honestly, it's hard to diagnose. I don't think fuel pressure target, pre-HPFP can be logged. If so that would be cool because you could look at the output of the LPFP vs the target. A large delta here would point to an issue with the low-pressure side supply. If your fuel pressure, low side, is good then you would know it is an issue with your HPFP.

If might be worthwhile to pay the $150 diagnostic fee to a reputable BMW mechanic and have them test both your low pressure and high-pressure fuel supply. You could do it yourself but need some special tools.

Also, I don't know about MHD, but with bm3 there are some additional parameters you could log to give you some insight.

LPFP (Raw)
LPFP Sensor Voltage (should be between 0.5-4.5 volts)

Overview of the fuel system

https://www.newtis.info/tisv2/a/en/f...ystem/F7eAStOK

https://www.newtis.info/tisv2/a/en/f...ystem/F7tmyyiA

Testing Procedures

https://www.newtis.info/tisv2/a/en/f...th-drive-line/

Originally Posted by AmuroRay

First - thank you for taking a look!
It’s a 93 octane tune - do you think that I’m in need of a HPFP or a LPFP?

[zole2112]

What codes did it throw? when my HPFP was going out it gave me 110001, 11A031 and 11A002 for fuel pressure and also 193001 for fuel level sensor. No misfire codes

[AmuroRay]

Originally Posted by zole2112

What codes did it throw? when my HPFP was going out it gave me 110001, 11A031 and 11A002 for fuel pressure and also 193001 for fuel level sensor. No misfire codes

I’ll check when I’m back at my car this evening.

[AmuroRay]

Shadow code(inactive) - 11CF30 mixture control: Multiple fault.
Active code - 118001 - mixture control: mixture too lean

[JaredG_F30]

118001 - mixture control: mixture too lean

Makes sense being that your rail pressure took a dive.

[ChanceG8X]

I would look into the upgraded HPFP as its basically maxed out stock AFR's are probably being sent through the 200's which is mostly air no fuel the HPFP in the car now probably can't handle higher end tunes.

heres the upgraded pump sadly its the only one on the market right now for N55's so its quite expensive.
http://tuningtechfs.com/ttfs-xdi-35-...grade-for-n55/

[AmuroRay]

Originally Posted by Chancef32

I would look into the upgraded HPFP as its basically maxed out stock AFR's are probably being sent through the 200's which is mostly air no fuel the HPFP in the car now probably can't handle higher end tunes.

heres the upgraded pump sadly its the only one on the market right now for N55's so its quite expensive.
http://tuningtechfs.com/ttfs-xdi-35-...grade-for-n55/

Yeah, I’m not going to do that, but I appreciate the suggestion. I’ll look into a stock pump or a modified B58. I’m not going to upgrade the turbo ever, so no need to that much headroom

[zole2112]

You have the same HPFP as me, stock turbo (mine is 335xi, don't know if we have the same turbo but mine is stock) and I am running JB4 Map 7 and MHD with BMS Race BEF, I run e50-e60 I am FBO and I have no issue with fueling so I don't believe you are maxing out your HPFP if I'm not unless I'm missing something, which I may be.

[Munchi435i]

Originally Posted by zole2112

You have the same HPFP as me, stock turbo (mine is 335xi, don't know if we have the same turbo but mine is stock) and I am running JB4 Map 7 and MHD with BMS Race BEF, I run e50-e60 I am FBO and I have no issue with fueling so I don't believe you are maxing out your HPFP if I'm not unless I'm missing something, which I may be.

How often do you datalog your car?

Any current logs you can share for comparison?