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      03-16-2018, 07:02 PM   #1
SaugaSoul92
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lpfp reading 82.5 psi on occasion

my cars been running like crap, and indy bmw mechanics tell me is fine (cause its not misfiring nor showing codes) but about once once a month my car will run great, so i hooked up mhd monitor and found that my low fuel sensor is reading 82.5 psi at idle and the car drives great! but the rest of the time its 72 psi and feels like its running lean. what would cause this?..any help would be appreciated

ride is 08 335xi 6mt

Last edited by SaugaSoul92; 03-16-2018 at 09:04 PM..
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      03-16-2018, 09:40 PM   #2
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Quote:
Originally Posted by SaugaSoul92 View Post
my cars been running like crap, and indy bmw mechanics tell me is fine (cause its not misfiring nor showing codes) but about once once a month my car will run great, so i hooked up mhd monitor and found that my low fuel sensor is reading 82.5 psi at idle and the car drives great! but the rest of the time its 72 psi and feels like its running lean. what would cause this?..any help would be appreciated

ride is 08 335xi 6mt
nothing to be concerned about... its in the normal range. if it ever drops below 50 during a pull then start looking for replacement.
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      03-16-2018, 10:30 PM   #3
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I run a walbro 450 in the stock bucket with no venturi. I get high numbers sometimes also. Causes me no issues so I leave it be.
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      03-17-2018, 02:47 PM   #4
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Originally Posted by Msport335 View Post
nothing to be concerned about... its in the normal range. if it ever drops below 50 during a pull then start looking for replacement.
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Originally Posted by WTF? View Post
I run a walbro 450 in the stock bucket with no venturi. I get high numbers sometimes also. Causes me no issues so I leave it be.
just did a log no it doesnt drop below 50 but i wish it would stay at 80 cause car is alot smoother and more responsive there
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      03-19-2018, 11:54 AM   #5
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Originally Posted by SaugaSoul92 View Post
just did a log no it doesnt drop below 50 but i wish it would stay at 80 cause car is alot smoother and more responsive there
That doesn't make any sense...post a log if you want help though.
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      03-19-2018, 07:06 PM   #6
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Originally Posted by FCobra94 View Post
That doesn't make any sense...post a log if you want help though.

https://datazap.me/u/soulrebel/new-o...20-21-22-23-24
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      03-19-2018, 07:29 PM   #7
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I see 80 - 85 PSI at various times with a 450 pump, no fueling issues
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      03-20-2018, 10:01 AM   #8
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Quote:
Originally Posted by SaugaSoul92 View Post
What's your mods and what fuel are you running? Looks like the fueling scalars are pretty far out hitting +22%, ideally these should be +-8%. While the DME is keeping you on AFR target large STFT deviations can cause a slight lack of smoothness. This doesn't appear to be the cause of your perceived problem though.

We need more information, does it run poorly at WOT, cruise, spool?
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      03-20-2018, 07:28 PM   #9
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Quote:
Originally Posted by bahn View Post
What's your mods and what fuel are you running? Looks like the fueling scalars are pretty far out hitting +22%, ideally these should be +-8%. While the DME is keeping you on AFR target large STFT deviations can cause a slight lack of smoothness. This doesn't appear to be the cause of your perceived problem though.

We need more information, does it run poorly at WOT, cruise, spool?
08 335xi
ams intercooler
ar downpipes
custom tune (this issue was also present on old tune)
238,000kms turbos changed at 150,000kms
94 octance
replaced post cat o2 sensors 2 weeks ago
no codes (except shadow in mhd fca fda hpfp)

so when approching 2.5 -3k rpms it seems to need alot of effort to redline, its rough and it takes alot of time to get to redline..

thx for helping

Last edited by SaugaSoul92; 03-20-2018 at 07:38 PM..
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      03-21-2018, 08:37 AM   #10
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Quote:
Originally Posted by SaugaSoul92 View Post
08 335xi
ams intercooler
ar downpipes
custom tune (this issue was also present on old tune)
238,000kms turbos changed at 150,000kms
94 octance
replaced post cat o2 sensors 2 weeks ago
no codes (except shadow in mhd fca fda hpfp)

so when approching 2.5 -3k rpms it seems to need alot of effort to redline, its rough and it takes alot of time to get to redline..

thx for helping
Who did the custom tune? I would not be happy with those fuel scalars and overboost if I were you.

Also in that log your pedal position is only at 58%, was this a WOT run or were you only slightly in it? The roughness you are feeling is probably due to the throttle position oscillation you can see here:

https://datazap.me/u/soulrebel/new-o...ta=2-3-5-22-25

The throttle closures are occurring because boost (and probably load) are over target. In my experience this is the DME's second choice for controlling overboost situations with the first being a WGDC intervention from the PID system. Generally when I see this it's either poorly configured WGDC control where the minimum WGDC value is too high and the PID system cannot decrease it further or the tune is in feed forward only mode where the PID system is disabled.

Please also log load act, load req, wgdc bank 1, wgdc base and wdgc after PID.
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      03-21-2018, 09:24 AM   #11
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Quote:
Originally Posted by bahn View Post
Who did the custom tune? I would not be happy with those fuel scalars and overboost if I were you.

Local tuner who was on here...he's moved on to gtr

Also in that log your pedal position is only at 58%, was this a WOT run or were you only slightly in it? The roughness you are feeling is probably due to the throttle position oscillation you can see here:

I was flooring it..

https://datazap.me/u/soulrebel/new-o...ta=2-3-5-22-25

The throttle closures are occurring because boost (and probably load) are over target. In my experience this is the DME's second choice for controlling overboost situations with the first being a WGDC intervention from the PID system. Generally when I see this it's either poorly configured WGDC control where the minimum WGDC value is too high and the PID system cannot decrease it further or the tune is in feed forward only mode where the PID system is disabled.

Please also log load act, load req, wgdc bank 1, wgdc base and wdgc after PID.
Will do...I really appreciate this! Do you recommend going back to stock?
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      03-21-2018, 09:34 AM   #12
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Quote:
Originally Posted by SaugaSoul92 View Post
Will do...I really appreciate this! Do you recommend going back to stock?
Stock will be just as bad or worst in terms of throttle closures due to your downpipes. The tune doesn't seem finished or you have something else effecting it like a recent modification that the tune was not adjusted for (downpipes, inlets, etc), was your foot 100% down on the accelerator pedal btw? If not you may have something blocking the pedal or the pedal could be failing as it was only seeing around 58%.
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