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  1. #1
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    Can't make make DME target max boost until 4,500 RPMs - Cobb Stage 1+ tweaked with ATR

    I have a 2009 335i sedan with manual trans and 54K on the odometer. Mods are a tweaked in ATR, stage 1+ 4.02 based map with BMS DCI and the Cobb intercooler.

    Basically what I find is its very difficult to make the DME target max boost until about 4,500 RPMS especially in a short gear like second. With my particular IJE0S DME I get all kinds of timing pulls (without corrections) if my actual load even gets close to the load target. Exceeding target boost, to a lesser extent, can also induce timing pulls (again without corrections). So I just set the load target at 200 throughout the midrange and then use the boost limit multiplier to dial in my boost curve which works well to keep the timing pulls at bay.

    I've actually increased the boost limit multiplier values corresponding to the airflows between 3,000 - 4,000 RPMs (higher than the airflows between 4,000 - 5,000) to try to increase the boost target in this range and it does help in the higher gears but not the lower ones. Load is at 200 at these RPMS and not the limiting factor.

    Log 935 is 3rd gear and we can see it does a good job of hitting 17 psi around 3,000 RPMS. I'm comfortable with that.

    Log 943 is 2nd gear and we can see it doesn't target max boost until around 4,500 RPMS. I can't seem to figure out why the different behavior in different gears. Its the same map.

    My question is specific to the requested boost in the 3,000 - 4,500 RPM range. I'm also curious to see if my spool is slow - I know nailing the gas at 2,500 won't produce instant boost but it looks like it could be spool a little faster especially on log 943. Or maybe this is about average while still on the stock down pipes.

    Some things to note - As far as being under the boost target in top of log 943 that is OK to me. I've taken out a good bit of WGDC up there and again do that because I get funky timing issues induced by exceeding boost target too, so by keeping it under target (but still hitting the actual boost I want) I get more consistent performance. Also, note at 180 load I'm only target 3 degrees of timing advance in the midrange and will start to add some more back in once I get the boost dialed in more. Log 943 has some minor corrections on cylinder 1 in the middle of the pull and log 935 actually has 0 corrections on all cylinders during the whole pull. I could probably even tweak the PID a little more to help with oscillations but I barely feel them in the drivers seat. As much I'd appreciate any advice on these side topics, I just have some more trial and error to get those issues dialed in more and would like this thread to stay on topic regarding requested boost between 3,000 - 4,500. Of course if there is anything else glaring that you feel really needs to be addressed please feel free to chime in. Any help is much appreciated.

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    2009 335i AT xdrive E90 Sedan
    7601494 Trans Flash
    MHD Custom Tune
    FBO + Rb Inlets

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    Nvm

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    Chrome Space Bar Issue: http://www.boostaddict.com/showthrea...338#post738338


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  4. #4
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    I looked over this thread earlier, but didn't have a chance to read thoroughly. Send me your map file and I'll take a look and see if there's anything odd. Include some extra info for me though: rom version, altitude, any codes, and anything else worth noting. Also, send me some logs in csv format.

    josh.dankel@cobbtuning.com
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    Maybe just an issue of boost control? Second log has some very bad boost oscillations. I'm assuming you had traction control completely disabled for these runs?
    2011 E90 M3 \ Melbourne Rot Metallic

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    Josh - I'll be emailing you everything you requested in a few. Thanks for the direct support

    Lul_m3 - I would like to calm down the osciallations. I think still need some work on the PID. I actually just had the DTC light showing (one press) and it wasn't completely off. However, the second log was in 3rd gear where I don't spin. And I have a fresh set of Michelin Pilot Sport A/S 3's on the car which are very grippy and conditions where dry and maybe around 65 degrees out. Technically I should have it all the way off to rule out the variable.
    2009 335i AT xdrive E90 Sedan
    7601494 Trans Flash
    MHD Custom Tune
    FBO + Rb Inlets

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