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  1. #1
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    N54 fueling related issue - help!

    Hey guys, New to the platform, been dealing with a fueling issue on my 08 n54 135i.

    Over the last few months i've been trying to solve the reason my car would splutter on every hard pull, felt like she was starving for fuel - first time i saw a superknock shadow code, did some logs, (my tuner adjusted fueling on the map so we avoid being too lean) it seemed like the lpfp was not holding up, ended up changing lpfp to the warlbro 450, low pressure would still only fluctuate around 55psi-65psi on WOT and 72psi at idle. The splutter did not go away so onto rail pressure which would sometimes dip below 1500psi, replaced hpfp with new OEM hpfp. since then she ran perfectly fine for some time, until a week or two ago, logs still look like she isnt fueling correctly - same with an mhd map

    I was pulling through 3rd gear and felt a tiny splutter which recovered very quickly during the pull, tried to get it to do the splutter again but i couldnt, a few days ago it happened again during a pull in 4th, this time i managed to replicate it in the log seems like fuel pressure dips dangerously (hpfp side) for some reason and thereafter recovers, the dip also throws a shadow code of superknocking in multiple cylinders. (i have not pulled the car since and dont plan to until i figure out the potential cause)


    Anybody tackle an issue like this? It is intermittent which has been confusing, she pulls strong with no codes 99% of the time.

    Somebody suggested ekp, i just want other opinions of those who know the platform well, i do not.
    Click here to enlarge

    Log uploaded.


    Mileage 125k km's, all maintenance up to date
    Downpipes, inlets, dci, warlbro 450, custom tune


    Attached Files Attached Files

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  3. #3
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    Just to add, this is on pump fuel only, no eth.

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    Throw that CSV into datazap.me and post the link, happy to take a look!

    Chris

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    2 out of 2 members liked this post. Yes Reputation No
    Hey man, Thanks a million!

    I cannot upload links as yet, i sent it to you via PM.

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    I presume stock turbos? Who is doing your tuning? What fuel are you using? Reset all of your fueling-related adaptations, and do another log. In your 4th gear log you have some significant issues going on. IMO not directly LPFP related.

    https://datazap.me/u/ismailb/splutte...5-22-25&mark=0

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    Hey Chris, turbos are locally built hybrids and i am also tuned by the same company that supplies them. In terms of fuel, currently i only use 95 as that is all we get here at the pump on the coast.

    Okay, let me reset adaptations and get those logs!

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    Your intake air temps reach 156F. That would be the biggest problem here. The LPFP and HPFP look OK.

    At 6.5k your fuel mode switches into cat protection mode because your AFR falls below the threshold in the map (running way too rich).

    Your fuel trims are really high around 4k, you would need to reset fuel adaptations and make mods to the fuel scalar table if the high trims persist.

    These are issues your tuner should be spotting. If you want to fix your car switch to a better tuner. Also I know it's backwards but you should swap to freedom units (F, PSI) for your logging since most people are familiar with those readings.

    Your ignition timing is also really low and you have lots of corrections. Really not a healthy map.

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    Click here to enlarge Originally Posted by Chris@PFS Click here to enlarge
    I presume stock turbos? Who is doing your tuning? What fuel are you using? Reset all of your fueling-related adaptations, and do another log. In your 4th gear log you have some significant issues going on. IMO not directly LPFP related.

    https://datazap.me/u/ismailb/splutte...5-22-25&mark=0
    Okay cool, adaptations reset and logs uploaded to datazap!

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    Click here to enlarge Originally Posted by CarAbuser Click here to enlarge
    Your intake air temps reach 156F. That would be the biggest problem here. The LPFP and HPFP look OK.

    At 6.5k your fuel mode switches into cat protection mode because your AFR falls below the threshold in the map (running way too rich).

    Your fuel trims are really high around 4k, you would need to reset fuel adaptations and make mods to the fuel scalar table if the high trims persist.

    These are issues your tuner should be spotting. If you want to fix your car switch to a better tuner. Also I know it's backwards but you should swap to freedom units (F, PSI) for your logging since most people are familiar with those readings.

    Your ignition timing is also really low and you have lots of corrections. Really not a healthy map.
    Thanks man! I've switch the units over to psi and logged again so it is easier to read. Glad to hear hardware seems okay, disappointing about the tuning bit! started to look into it and other options, just the response time with their busy schedules is crazy, especially for a remote tune. Hopefully i'm heading in the right direction now

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    Click here to enlarge Originally Posted by Ismail.B Click here to enlarge
    Thanks man! I've switch the units over to psi and logged again so it is easier to read. Glad to hear hardware seems okay, disappointing about the tuning bit! started to look into it and other options, just the response time with their busy schedules is crazy, especially for a remote tune. Hopefully i'm heading in the right direction now
    Looking at this datalog: https://datazap.me/u/ismailb/2nd-3rd...-30&solo=29-30

    Trims look better but still on the high side.

    IATs are way too high still. You need to upgrade your intercooler before going ahead with tuning the car.

    The tune is terrible, the wastegates are being controlled purely off the base table as the PID seems to be neutered which would explain why you are only achieving 16PSI when the tune is calling for 21.

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    Click here to enlarge Originally Posted by CarAbuser Click here to enlarge
    Looking at this datalog: https://datazap.me/u/ismailb/2nd-3rd...-30&solo=29-30

    Trims look better but still on the high side.

    IATs are way too high still. You need to upgrade your intercooler before going ahead with tuning the car.

    The tune is terrible, the wastegates are being controlled purely off the base table as the PID seems to be neutered which would explain why you are only achieving 16PSI when the tune is calling for 21.
    The reason behind using this tuner is due to the turbos supplied overshooting boost on the stock map as well as mhd maps, I approached the tuner about the overboost issue and they had informed me to check boost solenoids, vacuum leaks, downpipe clamps etc, I had a look at possible hardware causes, all seemed okay, I went back to them and they told me they could control it in a custom tune, I was told it was simple whereby they would adjust the requested boost and also play with the waste gate duty cycle to maintain boost under the requested. What would suggest as be a better way to control this? I do not have Jb4, only the custom tune through mhd, never had an overboosting issue since they did their adjustments, but everything else was just up to crap.

  13. #13
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    There are many respectable custom tuners out there that use MHD. BuraQ, V8Bait, Wedge, Motiv, not to mention the latest group of "newer" tuners. Regardless problem isn't fueling related, as much as tune related! Keep logging!!!!

    Chris

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