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  1. #1
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    Wink Cobb/Meth - Fuel Trim Tuning

    Just wanted to showcase some things on the horizon from the folks at Cobb. Josh@cobb was kind enough to let me play around with some new tuning abilities that Cobb has developed for the N54 DME. I will leave any details about it up to Cobb to release, i honestly have no idea where the stand in terms of putting this into a beta or OTS mapping product.

    Here is what my fuel trims looked like before any changes were applied.

    http://datazap.me/u/lulzm3/meth-race...?1-19-20-21-22

    Click here to enlarge





    Here's how things look after doing some initial testing, this is nowhere near dialed in, but shows that it can be effective.

    http://datazap.me/u/lulzm3/meth-fuel...913?1-20-21-22

    Click here to enlarge



    I'm planning on adding a 3rd Meth nozzle and cranking things up a bit, ill post new logs once i have had a bit more time to dial things in properly. Click here to enlarge
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    how about some 6at flatline fix?

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    Click here to enlarge Originally Posted by themyst Click here to enlarge
    how about some 6at flatline fix?
    The fix is buying a car with a proper transmission Click here to enlarge
    2011 E90 M3 \ Melbourne Rot Metallic

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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    The fix is buying a car with a proper transmission Click here to enlarge


    had a 6MT N54 before, not a fan of the gearing or feel of the box. 6AT is superior on this platform. just personal opinion, no need to start a tranny war.

    but would be nice for a proper fix.

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    I dunno.....maybe it's just me.....but your trims may be less negative with the updated map, but there seems to be more of a spread between the two banks than before?

    What nozzles are you using and where are they located?

  6. #6
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    Click here to enlarge Originally Posted by DCAFS Click here to enlarge
    I dunno.....maybe it's just me.....but your trims may be less negative with the updated map, but there seems to be more of a spread between the two banks than before?

    What nozzles are you using and where are they located?
    Yeah the trims between banks looks like crap, but that's not because of the tune. I'll be looking at that closer when get the 3rd nozzle hooked up. I suspect I may have a few injectors that could stand to be replaced also...
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  7. #7
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Just wanted to showcase some things on the horizon from the folks at Cobb. Josh@cobb was kind enough to let me play around with some new tuning abilities that Cobb has developed for the N54 DME. I will leave any details about it up to Cobb to release, i honestly have no idea where the stand in terms of putting this into a beta or OTS mapping product.

    Here is what my fuel trims looked like before any changes were applied.

    http://datazap.me/u/lulzm3/meth-race...?1-19-20-21-22

    Click here to enlarge





    Here's how things look after doing some initial testing, this is nowhere near dialed in, but shows that it can be effective.

    http://datazap.me/u/lulzm3/meth-fuel...913?1-20-21-22

    Click here to enlarge



    I'm planning on adding a 3rd Meth nozzle and cranking things up a bit, ill post new logs once i have had a bit more time to dial things in properly. Click here to enlarge
    this is the same thing I was trying to solve on my tune cobb hfs-4 high neg trims didn't seem to effect much but I was still trying to dial it in and never got it seemed like nothing made much of a difference .

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    Click here to enlarge Originally Posted by cwarren Click here to enlarge
    this is the same thing I was trying to solve on my tune cobb hfs-4 high neg trims didn't seem to effect much but I was still trying to dial it in and never got it seemed like nothing made much of a difference .
    Well you are adding a fuel source, so unless you can modify the DME's logic to reduce the amount of fuel it is calculating, you aren't going to get anywhere. Unless you run less meth, but that's no fun. Click here to enlarge

    Are you still running Cobb? Whats your rom type?
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  9. #9
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    Well, I wanted to give the DME some time to make any fuel adaptations and see how things would change... not much changed in terms of the variance in trims between each cylinder. http://www.datazap.me/u/lulzm3/fuel-...17-18-19-20-21

    Click here to enlarge

    So where do i stand? I'm thrilled to see that i reduced fuel trims by ~10%, and some fine tuning will make things look even better (all logs have been the same map, i haven't done any tweaking).

    One concern that has been looming in the back of my mind is "what happens if the meth is NOT there for fueling?" Theoretically the HFS4 fail-safe will have kicked in and dumped boost, but I'd rather err on the side of caution.

    I took a standard Cobb OTS S2+ Agg map, loaded my fueling changes to it and will run it with my meth kit turned off to monitor fuel trims. Depending upon how far positive the fuel trims go, this will tell me how much adjustability the DME will have to meet target AFR(in the case that methanol is no longer adding a fuel source).

    I want to cap fuel trims at +15, which will leave me an additional 19% of headroom. This will also vary depending upon many conditions, so better to stay safe and leave plenty of cushion. I will flash this map tomorrow and doing some logging and report. Additionally, i want to monitor my fuel trims off meth to help me understand why my fuel trims are so uneven. Typically this is a sign of poor meth distribution, but it could be related to other things - such as injectors. Hopefully this helps me narrow things down.
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    Just FYI, on my car on meth all new injectors, trims vary 5% from each other..atm i have two 1mm nozzles in the standard ER charge pipe location (pre BOV)..100% meth

  11. #11
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    Click here to enlarge Originally Posted by dzenno@PTF Click here to enlarge
    Just FYI, on my car on meth all new injectors, trims vary 5% from each other..atm i have two 1mm nozzles in the standard ER charge pipe location (pre BOV)..100% meth
    Ok, that's close to what i am seeing. I have already tapped my cold side up pipe for another nozzle, just wanted to get some good logs and data beforehand. I'm interested to see how much difference that location will make with respect to the fuel trim divergence. Instead of running 3 nozzles right away, i may move one nozzle down to that location and gather some more logs first. I remember seeing @Tzu doing alot of testing that appeared to be along the same lines of nozzle placement. I should go revisit that thread..
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  12. #12
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    The TLDR for the meth nozzle location thread is: further upstream = better. I'm thinking my particular problem is likely procede related, and I'll test that when it's too cold here to have fun by disengaging piggy and logging DME.

  13. #13
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    Click here to enlarge Originally Posted by Tzu Click here to enlarge
    The TLDR for the meth nozzle location thread is: further upstream = better. I'm thinking my particular problem is likely procede related, and I'll test that when it's too cold here to have fun by disengaging piggy and logging DME.
    Just wanted to report back that you are absolutely correct, moved one of my 1.0mm nozzles upstream and now my fuel trims are much closer.
    http://www.datazap.me/u/lulzm3/meth-...12-15-18-19-22
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  14. #14
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    My trims on ACN91 PTF map go from 30% to 12%. AFRs 13 to 11. Am I running too lean? Or LPFP can't keep up?
    Click here to enlarge
    MOTIV750 / MHD+JB4 / ADV / SB REAR O2

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    putting the nozzles in the fmic end tanks seem to fix the difference. I've been meaning to do that myself but I'm just too damn lazy
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Just wanted to report back that you are absolutely correct, moved one of my 1.0mm nozzles upstream and now my fuel trims are much closer.http://www.datazap.me/u/lulzm3/meth-...12-15-18-19-22
    Excellent.

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