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  1. #1
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    Is my LPFP dying?

    Here's the log 1st gear into 2nd gear which slipped due to bald PSS rears.

    I see that Fuel LPFP PSI drops to 45 but LTFT Bank 1 stayed at 0%.

    Is anyone coming out with a PNP replacement solution?

    http://datazap.me/u/blisstik/ptf-s2-...slip?1-2-21-22

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    I would love to see a PNP like DW did with the DW65 for the Subaru market.

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    Here's a more recent run. This is on PFT S2 map with 7/8 ACN 91 and 1/8 E50 mix from previous fill. The LPFP PSI spikes down into high 40s.

    http://datazap.me/u/blisstik/ptf-s2?1-2-7-20-21

  4. #4
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    Click here to enlarge Originally Posted by blisstik Click here to enlarge
    Here's a more recent run. This is on PFT S2 map with 7/8 ACN 91 and 1/8 E50 mix from previous fill. The LPFP PSI spikes down into high 40s.

    http://datazap.me/u/blisstik/ptf-s2?1-2-7-20-21
    It seems ok to me, but it seems like your ethanol content might be higher than you believe.., your fuel trims are maxing out +34 @ 3900 RPM. Fuel scalar needs some massaging.
    2011 E90 M3 \ Melbourne Rot Metallic

    Click here to enlarge

  5. #5
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    Are you using the OEM LPFP or one of the aftermarket options (Walbro 450/Inline Pump, etc etc)?
    COBB AP ProTune by Bren of ///Bren Tuning
    Akrapovic DP | Helix FMIC | Alpina TCM Flash | Walbro 450LPH Fuel Pump


    "The moment money becomes your motivation, you are immediately not as good as someone who is motivated by passion and internal will." -A. Senna

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    It's OEM LPFP, 90K+ on the car now. I'm thinking of doing the Walbro GSL392 as an inline. Now that I think of it, I had 1/4 tank of E50 left and I pumped until 1/2 a tank. Is that what's causing STFT spikes? I have added more pump just today.

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    Click here to enlarge Originally Posted by blisstik Click here to enlarge
    It's OEM LPFP, 90K+ on the car now. I'm thinking of doing the Walbro GSL392 as an inline. Now that I think of it, I had 1/4 tank of E50 left and I pumped until 1/2 a tank. Is that what's causing STFT spikes? I have added more pump just today.
    Your STFT's are clearly maxed out and don't go sub 30% until ~4,800 RPMs; I've been taking some logs recently and I'm having very similar symptoms (but with the Walbro 450) -- Near 0% LTFTs, maxed out STFTs on 93 octane, AFR/Lambda is a little more lean than your's, but still okay.

    After ~2 weeks of back and forth, it's been determined that either the Walbro LPFP is dying OR there's a restriction somewhere in the fuel lines in the tank. Since you're still using the OEM pump, I assume that your fuel lines aren't the problem and that the LPFP is possibly dying from the higher demand placed on it from running ethanol blends & aggressively tracking the car (from your sig pic).

    Try to run all the gas out, run a tank of pump gas with minimum ethanol & re-log. If your STFT fuel trims are still out of whack on pump gas, it's obvious that it's something related to the LPFP-fueling side.
    COBB AP ProTune by Bren of ///Bren Tuning
    Akrapovic DP | Helix FMIC | Alpina TCM Flash | Walbro 450LPH Fuel Pump


    "The moment money becomes your motivation, you are immediately not as good as someone who is motivated by passion and internal will." -A. Senna

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    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    Try to run all the gas out, run a tank of pump gas with minimum ethanol & re-log. If your STFT fuel trims are still out of whack on pump gas, it's obvious that it's something related to the LPFP-fueling side.
    I had about 1/4 tank left of the 50/50 pump/E50 mix and added 5-6 gallons of 91 ($25 worth). I relogged (see links below) and noticed that STFT Bank 1 and 2 have a constant 6% to 8% difference throughout the band. HPFP PSI doesn't drop and continues to go up when LPFP PSI is at its lowest.

    http://datazap.me/u/blisstik/106?1-2-13-14-18-19
    http://datazap.me/u/blisstik/107?1-2-13-14-18-19

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    IMO, if HP fuel isnt taking a dive, then I wouldn't worry about it too much. Unless the LPFP is causing drivability issues, it's more of a preventative thing to beef up the fueling system, peace at mind IMO. shiv once stated that he recommended replacing the LPFP if the voltage dips below 2V during a pull. Is the pressure output linear to voltage?

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    Click here to enlarge Originally Posted by Tzu Click here to enlarge
    IMO, if HP fuel isnt taking a dive, then I wouldn't worry about it too much. Unless the LPFP is causing drivability issues, it's more of a preventative thing to beef up the fueling system, peace at mind IMO. shiv once stated that he recommended replacing the LPFP if the voltage dips below 2V during a pull. Is the pressure output linear to voltage?
    I'm not sure if Access Port can log LPFP voltage. I'll take a look at this. Thanks!

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    Update: I have replaced the OEM LPFP and added the inline Walbro at the same time. Trims are still hitting 30% ~4500 RPM and tapers down. Take a look at the new log below.

    http://datazap.me/u/blisstik/114?1-2-18-19-22

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    How much E are you running?

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    ACN 91!

    Click here to enlarge Originally Posted by Tzu Click here to enlarge
    How much E are you running?

  14. #14
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    Who installed both LPs? I would've said just replace the OEM LPFP and see if that diagnosis the problem, but now there's another variable since you added the Walbro inline pump.

    Are you having any cold start/idle problems? There's a noticeable deviation between your Bank 1 & Bank 2 Fuel Trims so Injector Failure is a possibility.
    COBB AP ProTune by Bren of ///Bren Tuning
    Akrapovic DP | Helix FMIC | Alpina TCM Flash | Walbro 450LPH Fuel Pump


    "The moment money becomes your motivation, you are immediately not as good as someone who is motivated by passion and internal will." -A. Senna

  15. #15
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    The Walbro is working just fine. Idle LPFP PSI is ~87-88. Brand new OEM LPFP by itself would be much lower.

    I do see that there's up to 10% deviation between both banks. I've read around and folks say that's "normal".

    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    Who installed both LPs? I would've said just replace the OEM LPFP and see if that diagnosis the problem, but now there's another variable since you added the Walbro inline pump.

    Are you having any cold start/idle problems? There's a noticeable deviation between your Bank 1 & Bank 2 Fuel Trims so Injector Failure is a possibility.

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