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      05-20-2019, 06:21 PM   #1
erzenble
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MHD link- Bad HPFP?

Run on my 2011 335i just flashed to MHD stage 1 91 octane. now my fuel pressure is really fluctuating and car goes lean when it does. lots of timing corrections where the psi drops. This is proof my HPFP is toast right? Or could my LPFP be the problem? Thanks guys.

https://datazap.me/u/erzenble/2011-3...38&tmax=100.70

Last edited by erzenble; 05-20-2019 at 06:35 PM..
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      05-20-2019, 06:58 PM   #2
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Your pressure at the rail looks fine, never drops below 2000psi. You need to log your lpfp sensor to see the low pressure fuel pump but it should be fine since your rail pressure isn't dropping low.
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      05-20-2019, 06:59 PM   #3
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test
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      05-20-2019, 07:13 PM   #4
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[QUOTE=IllSic_Design;24810060]Your pressure at the rail looks fine, never drops below 2000psi. You need to log your lpfp sensor to see the low pressure fuel pump but it should be fine since your rail pressure isn't dropping low.[/QUOTE=

hmm the psi drops from 3300 psi down to 2500 psi and back a few times, each time it does that my AFR goes lean and right at the same time i was getting timing corrections in most cylinders up to -6. Is a 1000 psi drop not a problem?

I was also getting corrections with stock MAP.
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      05-20-2019, 11:38 PM   #5
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Anyone know how to log LPFP on MHD? I dont see the option anywhere.
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      05-20-2019, 11:57 PM   #6
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oh you have N55, I don't think you have a lpfp sensor if I remember correctly.
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      05-21-2019, 08:33 AM   #7
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Quote:
Originally Posted by erzenble View Post
Run on my 2011 335i just flashed to MHD stage 1 91 octane. now my fuel pressure is really fluctuating and car goes lean when it does. lots of timing corrections where the psi drops. This is proof my HPFP is toast right? Or could my LPFP be the problem? Thanks guys.

https://datazap.me/u/erzenble/2011-3...38&tmax=100.70
not expert but your boost is always under 10psi? even when boost targets requesting 14psi....
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      05-21-2019, 08:50 AM   #8
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Quote:
Originally Posted by IllSic_Design View Post
oh you have N55, I don't think you have a lpfp sensor if I remember correctly.
you're correct
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      05-21-2019, 08:59 AM   #9
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Quote:
Originally Posted by IllSic_Design View Post
oh you have N55, I don't think you have a lpfp sensor if I remember correctly.
Wow I'm baffled how their car don't have a LPFP? Why lol.
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      05-21-2019, 11:52 AM   #10
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Quote:
Originally Posted by RomKaN54 View Post
not expert but your boost is always under 10psi? even when boost targets requesting 14psi....
yes exactly, im not making target boost either. I think the DME is limiting my boost since i have other problems.
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      05-21-2019, 11:59 AM   #11
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anyone mind throwing in there HPFP logs for a comparison? from what i read the pressure is supposed to be pretty steady with no sudden drops because if its not steady it will change the amount of fuel thats supposed to be injected and mess up AFR's.

Was hoping someone could confirm or tell me im wrong before i spend 500 dollars on a pump. There not cheap unfortunately.
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      05-21-2019, 02:20 PM   #12
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post in here, you will get more help https://www.e90post.com/forums/showt...hlight=mhd+log
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      05-21-2019, 02:37 PM   #13
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Quote:
Originally Posted by IllSic_Design View Post
post in here, you will get more help https://www.e90post.com/forums/showt...hlight=mhd+log
Will do thanks.
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      05-21-2019, 02:54 PM   #14
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Quote:
Originally Posted by erzenble View Post
Run on my 2011 335i just flashed to MHD stage 1 91 octane. now my fuel pressure is really fluctuating and car goes lean when it does. lots of timing corrections where the psi drops. This is proof my HPFP is toast right? Or could my LPFP be the problem? Thanks guys.

https://datazap.me/u/erzenble/2011-3...38&tmax=100.70
This has been discussed alot on mhd forum. Its related to the newer maps when pressure goes above 2800 psi.

If u flash to stock u wont see this issue.
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      02-05-2024, 03:53 PM   #15
ilikemycar
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Quote:
Originally Posted by erzenble View Post
Run on my 2011 335i just flashed to MHD stage 1 91 octane. now my fuel pressure is really fluctuating and car goes lean when it does. lots of timing corrections where the psi drops. This is proof my HPFP is toast right? Or could my LPFP be the problem? Thanks guys.

https://datazap.me/u/erzenble/2011-3...38&tmax=100.70
Hey man. Same issue here, how did you fix it? My graph looks same.
Thanks for info.
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      02-06-2024, 11:00 AM   #16
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Quote:
Originally Posted by erzenble View Post
Run on my 2011 335i just flashed to MHD stage 1 91 octane. now my fuel pressure is really fluctuating and car goes lean when it does. lots of timing corrections where the psi drops. This is proof my HPFP is toast right? Or could my LPFP be the problem? Thanks guys.

https://datazap.me/u/erzenble/2011-3...38&tmax=100.70
Which parameter from your log indicates 'fuel pressure is really fluctuating' ? Is there a fuel pressure parameter in your log other than 'rail pressure mean psi'? My JB4 logs provide hpfp and lpfp numbers but I don't see that your MHD log has any comparison parameters.
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