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Thread: Help getting an initial calibration close - Swapped E36

  1. #1
    Potential Tuner
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    Aug 2017
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    Help getting an initial calibration close - Swapped E36

    Greetings all,

    I've been working on an 4.8 swapped E36 for some time now. I've had mixed success with getting the base calibration setup properly so I figured I'd reach out to the community for some help.

    Overview of the swap:
    '92 325iS
    T56 Magnum
    '01 rebuilt 4.8 (bought as a 5.3 only to find out it was a 4.8. used as experience to blueprint)
    LS1 intake
    LS1 injectors from Corvette (P/N 12555894)
    LS6 MAF (6" straight on each side of MAF)
    Bored 0.030" over
    Comp Cams XFI RPM - ~.560 lift int/exh, 224/224 duration, 112 LSA
    Customer headers into y-pipe (3" diameter from collectors back)
    Wiring specialties E36 LS1 harness
    no A/C, no PS, underdrive crank damper

    I have widebands from 14point7 I need to wire up. I have an old harness that I need to check for A/C and EGR wiring to use as a sacrifice into my harness.

    The vehicle speed signal is contained in the rear end so I don't have a vehicle speed signal in the log file.

    With regards to the tune, I started with a 4.8/5.3L tune, copied over the LS1 injector flow rates and VE tables. Based on previous logs, I also reduced the MAF curve by a factor of 0.85. I increased the base idle speed by a factor of 1.1 to help idle during warm up. Reading around, I'm already noticing that my cylinder volume value is wrong, so I'll need to correct that.

    I've attached the tune I'm working off of and a log file from a drive in my subdivision today. I'm still learning to use HP Tuners and understand GM tuning, but I have experience on small engines with standalone and on OEM calibrations (emulated modules and expensive DAQ has me spoiled). I greatly appreciate any help or feedback I can get. Thanks in advance! If this doesn't belong here, please let me know where the appropriate posting section is.

    1992_BMW_325i_4.8L_LS_Rev2_Base+LS1Fueling+LS1VE+UpIdle+reduceMAF.hpt20200407_Rev1_VetteFuelingVE_HigherIdle_LowerMaf_drive.hpl

    EDIT: Forgot to mention I'm reading ~70 psi on a FAST gauge at the rail. What do I need to change to get the fueling properly adjusted for that? This seems higher than the 58 PSI I would expect from a Corvette FPR (I think).

  2. #2
    Senior Tuner
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    Mar 2011
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    Ripley, MS
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    I'd recommend changing the cylinder volume, and a couple of other things.

    I'd adjust the IFR table by the square of the divisor of the pressures. IFR Multiplier = (70/58)^.5
    That'll be 1.098 times your current IFR table. It'll be a much more accurate representation of what your injectors are flowing.

    You will typically have a higher base airflow when in gear, as opposed to in P/N, so I would adjust that accordingly.

    You also need to increase the minimum airflow through your throttle body in order to get the IAC within an acceptable range. It's 124-130 now when warmed up. It should be around 40-60. Simply turn the throttle body screw by one full round to start with. Cycle the key off and on in order to recalibrate the TPS, and try it. Rinse and repeat until you get the IAC within range.

  3. #3
    Potential Tuner
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    Aug 2017
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    Thanks! That definitely helped get the fueling in line. I'm still in process of setting the throttle screw, but the IAC appears to be more stable. Hot restarts need some work and I get occasional stalls coming to a stop after shifting to neutral. Do you think getting the IAC in the correct range will help improve return to idle?

    20200408_Rev3a_CSW_drive.hpl

  4. #4
    Senior Tuner
    Join Date
    Mar 2011
    Location
    Ripley, MS
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    Getting the IAC counts in the proper range will likely fix the stalling issue. Occasionally, I'll just bend the throttle tab just a bit in order to get the IAC where it needs to be. Just be careful to keep the TPS voltage less than .82V at idle. Anything above that will kick it to non-idle mode.

    I'd also remove another 5% fuel from the idle area. That'll get your fuel trims really close.

    I'd also set the minimum airflow table to around 10.5 g/s when it's up to temp.