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Thread: My turbo build-initial test drive and target AFR and VE ma quesitons

  1. #1
    Join Date
    May 2007
    Location
    Florida
    Posts
    2,158
    My Cars
    '87 325is 24v turbo buil

    My turbo build-initial test drive and target AFR and VE ma quesitons

    Hey everyone, i finally got to take my initial test drive this past weekend after nearly 3 years of owning and building my car.

    1987 325is
    m52b28 swapped
    m50 manifold
    RSI/Good & Tight manifold
    Precision 5557 turbo
    on3 performance 44mm waste gate and BOV
    AEM wideband
    Siemens 60lb injectors
    IAC valve delete

    The car fires up immediately, idles really well, and revs well. What I have noticed however is if I give it a slight amount of throttle off idle it spikes very lean, but if I stab the throttle all looks well. On my test drive around the block, it ran pretty well for a base tune that needs a lot of tweaking, but again, trying to give it very light throttle inputs gives a bit of a stutter.

    Here is my target AFR map, I would love suggestions on if I should change anything:
    Target AFR.JPG

    And here is my VE table thus far:
    VE map before full autotune.JPG

    This has VERY little tuning done too it so far, so I know the VE table isn't right yet, and I am going through the auto tuning and data logging process currently, but are there any obvious numbers I could change to make the process quicker? Right now the car does not hit the target AFR's at all, and is actually VERY rich except for the slight throttle lean scenarios.

    And a quick clip because after 3 years I was so proud this thing actually moved!
    https://www.instagram.com/p/BuPRg6UB...on_share_sheet

  2. #2
    Join Date
    Feb 2017
    Location
    Minneapolis, Minnesota
    Posts
    273
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    1995 BMW 525i/5
    Regarding your issue with it leaning out on light throttle pressing, play with your acceleration enrichment. Don't focus too hard on the actual AFR number when playing with this, go off of feel. You likely need some more fuel added on the light pedal pressing.

    Sent from my Pixel 3 XL using Tapatalk
    '95 E34 525i, M50B32 (S52 Crank, K1 Rods, JE 9.0:1 Pistons, S52 Cams, Cutring, Achilles Oil Pump Shaft & Sprocket), GTW3684R 0.82A/R, ZF320

  3. #3
    Join Date
    Aug 2011
    Location
    philadelphia PA
    Posts
    461
    My Cars
    1993 325is
    Is it a drift car?

  4. #4
    Join Date
    May 2007
    Location
    Florida
    Posts
    2,158
    My Cars
    '87 325is 24v turbo buil
    Definitely not a drift car. The car started out as a weekend fun car project. I found rust on the roof line and a few other places, and the car snowballed into a stripped out, half caged, completely solid mounted track oriented car...

  5. #5
    Join Date
    Feb 2019
    Location
    USA
    Posts
    1
    My Cars
    2001
    Hi,

    i am new here please welcome me.

  6. #6
    Join Date
    Apr 2006
    Location
    Minnesota eh?
    Posts
    6,155
    My Cars
    86 325es
    The fuel table needs alot of tuning, but to fix the lean spike with throttle changes you need to tune the Accel enrichment table. Like Puff said above you will likely never get the AFR to read correctly with throttle changes, it needs to be tuned by feel so that it does not stumble with throttle changes.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  7. #7
    Join Date
    May 2007
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    Florida
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    '87 325is 24v turbo buil
    Quote Originally Posted by someguy2800 View Post
    The fuel table needs alot of tuning, but to fix the lean spike with throttle changes you need to tune the Accel enrichment table. Like Puff said above you will likely never get the AFR to read correctly with throttle changes, it needs to be tuned by feel so that it does not stumble with throttle changes.
    For sure the VE table is not correct. I have literally only made one lap around the neighborhood as a shakedown to make sure nothing was going to fall off, lol. I got the car registered this morning, so now I feel a lot better about driving it around to get datalogs and to let auto tune work it's magic.

    I have been looking at how to tune for accel enrichment this morning between customer calls, and hopefully I am grasping the concept ok. If anyone has preferable settings, that would be great, but it seems like its something you have to do on a case by case basis over several datalogs. What I do know for sure is that the accel enrichment settings were not set based on TPS, which I have no rectified. I am just trying to better understand the parameters now.

  8. #8
    Join Date
    Aug 2011
    Location
    philadelphia PA
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    1993 325is
    Its best to tune your fuel table completely before you start dialing in the enrichment (steady state stuff). You could be coming across some lean cells when you blip the throttle, Adding enrichment fuel will make it run well but those cells may still be lean and show their head at other times.

    You don't really need to taper richer towards redline. That's why I asked if its a drift car. They spend alot of time on the limiter at slow speeds with crappy cooling so the extra fuel up there can help.


    When using autotune there is some technique to make it work better for you.

    -Smooth and steady on the throttle. Try to focus on one specific rpm column at a time and try to stay in each load block as long as you can. I typically cruise on a low populated road in various gears to hold rpm constant, varying load by riding the brake and modulating that way.
    -Use the "Smoothing" feature often. Autotune generally makes the table pretty damn lumpy. Smoothing often will yield you a better running engine but also make auto tunes job easier and quicker when the cells are in the ballpark already
    -Observe the pattern of the VE table as its coming into shape. After tuning a few rows at various loads you can start to predict where things are heading. This is also useful for populating areas on the table that are hard to hit on the street or dyno.
    -Did I mention use the smoothing feature often?
    -The autotune settings you showed are VERY aggressive. Play carefully with that. You may consider adding some rules or taking away some authority once you start going into boost.
    - Dont forget that missfires leave unburned o2 in the exhaust. Autotune will start pulling fuel at this point, but you dont want that.

    AutoTune is good for getting the table in the ballpark. After its within an AFR or so I would recommend disabling it and hand editing the rest. Keep it smooth.

    Once you are confident that the steady state tuning is really close, now play with your accel enrichment. Like others said, dont use your AFR for this. Close your eyes if you have to. Keep blipping as you add or subtract enrichment until the engine feels right.

  9. #9
    Join Date
    May 2007
    Location
    Florida
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    '87 325is 24v turbo buil
    Quote Originally Posted by Gmfwd View Post
    Its best to tune your fuel table completely before you start dialing in the enrichment (steady state stuff). You could be coming across some lean cells when you blip the throttle, Adding enrichment fuel will make it run well but those cells may still be lean and show their head at other times.

    You don't really need to taper richer towards redline. That's why I asked if its a drift car. They spend alot of time on the limiter at slow speeds with crappy cooling so the extra fuel up there can help.


    When using autotune there is some technique to make it work better for you.

    -Smooth and steady on the throttle. Try to focus on one specific rpm column at a time and try to stay in each load block as long as you can. I typically cruise on a low populated road in various gears to hold rpm constant, varying load by riding the brake and modulating that way.
    -Use the "Smoothing" feature often. Autotune generally makes the table pretty damn lumpy. Smoothing often will yield you a better running engine but also make auto tunes job easier and quicker when the cells are in the ballpark already
    -Observe the pattern of the VE table as its coming into shape. After tuning a few rows at various loads you can start to predict where things are heading. This is also useful for populating areas on the table that are hard to hit on the street or dyno.
    -Did I mention use the smoothing feature often?
    -The autotune settings you showed are VERY aggressive. Play carefully with that. You may consider adding some rules or taking away some authority once you start going into boost.
    - Dont forget that missfires leave unburned o2 in the exhaust. Autotune will start pulling fuel at this point, but you dont want that.

    AutoTune is good for getting the table in the ballpark. After its within an AFR or so I would recommend disabling it and hand editing the rest. Keep it smooth.

    Once you are confident that the steady state tuning is really close, now play with your accel enrichment. Like others said, dont use your AFR for this. Close your eyes if you have to. Keep blipping as you add or subtract enrichment until the engine feels right.
    Thanks a lot for the suggestions! I was curious about the smoothing factor as I hadn't used it yet. There isn't a way to have it automatically smooth cells is there, or is that something you need to do manually every time?

    One of the reasons I have cell change resistance set to "very easy" is because I really have a hard time getting the car to even get to target AFR's currently. It runs VERY rich in all instances except light throttle inputs as mentioned already. Would it make sense to leave it this way for a few very light runs to get slightly closer and tehn back it off?

  10. #10
    Join Date
    Apr 2006
    Location
    Minnesota eh?
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    86 325es
    You can tune the accel enrichments about 80% of the way just playing with it in the driveway.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  11. #11
    Join Date
    Aug 2011
    Location
    philadelphia PA
    Posts
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    1993 325is
    Quote Originally Posted by SS Ball3r View Post
    Thanks a lot for the suggestions! I was curious about the smoothing factor as I hadn't used it yet. There isn't a way to have it automatically smooth cells is there, or is that something you need to do manually every time?

    One of the reasons I have cell change resistance set to "very easy" is because I really have a hard time getting the car to even get to target AFR's currently. It runs VERY rich in all instances except light throttle inputs as mentioned already. Would it make sense to leave it this way for a few very light runs to get slightly closer and tehn back it off?
    I haven't used tuner studio in a while but I think you just highlight the cells you want to smooth and click a smooth button. Or maybe right click. Only smooth cells that are close to correct, so you arent interpolating BS numbers into good numbers

  12. #12
    Join Date
    May 2007
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    Florida
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    '87 325is 24v turbo buil
    Quick question i'm hopin g to get answered befofe saturday morning. Can i datalog while autotune is running? And by that, i know i can run a datalog at the same gime, but is te data going to be worthless? I got my car registered this week, have my exhaust nearly complete enough to not fear drawing too much attention to myself, and i want to start doing some good tuning runs early saturday morning whne there shouldnt be any traffic...I like living where I live, but god damn the traffic is getting bad lately...

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