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2G EPROM Tuning

Posted by Ceddy, Apr 14, 2007

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  1. Ceddy

    Ceddy Proven Member

    Joined May 10, 2006
    Reading, Pennsylvania
    Ceddy's 2G EPROM How-To

    What you need:
    Eprom Programmer
    27SF512 70ns Eprom
    Socketed 95 Eprom ECU

    prog.jpg chip.jpg

    I will be using the EB23C image from a 1995 5-speed AWD. You can use this image on an Automatic, all tranny stuff is handled by the TCU.

    Stock Image - EB23C.BIN

    Fuel Cut is one of the best reasons modify your factory eprom image. It is safety measure that cuts fuel if flowing more then 2.5 g/rev of air. One way to modify it is raise it to its max value, about 4 g/sec. While this good for like 400 HP, its only a band aid. It is best to remove this check altogether. Simply NOP it out.

    d6 5f .. ldab *0x5f .. Load Air Flow
    c1 a0 .. cmpb #160 ... Compare to 2.5 g/rev
    24 05 .. bcc 0x5111 .. Branch if greater

    Fuel Cut removed - FUELCR.BIN

    If all you want to do is remove fuel cut, you're done. Burn this image to a chip, pop it in, and turn up the boost.

    Rev Limiter cuts fuel and ignition when rpms are to high for the stock head. Higher rpms will cause valve float and valve to piston contact. To change the stock value of 7500 rpm, simply edit the value in the image.

    fc 01 8b .. ldd 0x18b ....... Load rpm
    1c 01 f4 .. cmpd #0x1f4 ..... Check rev limit
    24 05 ..... bcc 0xcc10
    03 ad 04 .. orm *0xad #$04 .. Under rev limit set bit 3
    20 03 ..... bra 0xcc13
    02 ad fb .. andm *0xad #$fb . Over rev limit reset bit 3

    limit rpm = 3750000 * 0x1F4 = 7500
    data value = desired rev limit / 3750000
    So... 7200 rpms = 0x209, 7500 = 0x1f4, 7800 = 0x1e1, 8000 = 0x1df

    Rev Limit 7200 rpm and Fuel Cut Removal - FCR7200.BIN
    Rev Limit 7500 rpm and Fuel Cut Removal - FCR7500.BIN
    Rev Limit 7800 rpm and Fuel Cut Removal - FCR7800.BIN
    Rev Limit 8000 rpm and Fuel Cut Removal - FCR8000.BIN

    Injector Compensation and Dead Time
    So far I've been giving you the BINs premade, for now on you are going to have to edit them yourself. To do this you are going to need a program like TunerPro and a definition file for BIN you editing. Heres one I made EB23C_V2.XDF. This XDF was updated to V2 on 5/28/07.

    Start up TunerPro and load your BIN and XDF. Then open up the Injector Size menu.
    Change to your injector size and save. Then open up the Dead Time menu.
    deadtime.jpg deadtime2.jpg
    Add your dead time to each value in the table. In the example above I added 180 uS to each value. Don't forget to save.

    If your Short Term Fuel Trims are running rich you need to decrease dead time. If lean you need to increase dead time. Dead time has less and less significance above idle rpms.

    If you are running rich at rpms above idle you need to increase injector size. If lean then decrease injector size.

    Idle Speed adjustment is often necessary when very aggressive cams or a built up head is installed. Stalling when idleing or coasting to a stop is a sign that idle speed should be raised. Open up the Idle menu.
    The first two numbers are the base idle speed. The remaining six numbers are the idle speed at colder and colder temps, used when the car is warming up. You should add the amount you wish to raise base idle to all numbers. So if you wished to raise idle to 1000 rpm, you would add 232 to all of the numbers.

    Note: This will adjust idle speed in the ecu only. You will also have to adjust the BISS on the throttle body. See the VFAQ for more info.

    Fuel Map editing is useful for fine tuning your car. The factory maps are really rich up top and can be safely leaned out if you run premium gas.
    The up and down axis labels are first psi or vac then grams/rev. These are approximate values only, actual values depend on air temp and barometric pressure. As you can see the top most row only goes up to 10 psi. This means when ever your running over 10 psi only the top row is being used. This means the top row is very important when optimizing the fuel map.
    The above map has been optimized to top out at 10.5 You should tune your fuel map with a wideband to create your perfect fuel curve.

    Note: There are four fuel maps that correspond to California / Federal and AWD / FWD. They are selected by two config resistors on the ecu board. You could change one map at a time to find which one is selected. Or simply change all four. Modify one map to what you want, then copy and paste to the remaining three.

    Timing map editing is essential to get the most power out of your engine. Besides raising boost, raising(or lowering) timing will will have the most significant effect on engine performance. Like the fuel maps there are also four timing maps. But there are also two octane maps.
    The octane map has lower timing. It is used when knock is detected. If there is no knock then a value from the timing map is used. If there is a little knock then a value in between the two maps is used. And if there is alot of knock a value from the octane map is used.

    You should increase timing until knock is detected for max power. Unfortunately the 2g cannot log knock. This presents a problem, you can watch where timing is pulled to try to see where you are knocking, but this isn't easy or accurate. Search on Tuners to see how to look for pulled timing.

    I'm running a chip now that flashes the Check Engine Light when knock is detected. I also have been experimenting with swapping a logged value like Coolant Temp with Knock Sum to be able log knock. Once the bugs are worked out, I will make these available.

    If you would like to know more about programming the dsm ecu, check out:
    My site -> www.ceddy.us
    and Yahoo Groups DSM-ECU -> autos.groups.yahoo.com/group/dsm-ecu/
    Last edited by a moderator: Jul 10, 2014
  2. Ceddy

    Ceddy Proven Member

    Joined May 10, 2006
    Reading, Pennsylvania

    Injector Brand ------- Flow cc/min --------- Deadtime uSec

    1G/2G --------------------- 450 --------------------- 0

    Clinic 750 ---------------- 750 --------------------- 330
    Clinic 850 ---------------- 850 --------------------- 330
    Clinic 950 ---------------- 950 --------------------- 330

    Delphi 680 ---------------- 680 --------------------- 210

    Denso 660 ----------------- 660 --------------------- 180
    Denso 720 ----------------- 720 --------------------- 405 - 450

    FIC 650 ------------------- 650 --------------------- 210
    FIC 750 ------------------- 750 --------------------- 315 - 330
    FIC 850 ------------------- 850 --------------------- 315 - 330
    FIC 950 ------------------- 950 --------------------- 315 - 330

    Hahn RC 625 --------------- 530 --------------------- 180

    ND 560(Evo8) -------------- 560 --------------------- -48
    ND 660 -------------------- 660 --------------------- 180

    PTE 580 ------------------- 535 --------------------- 180
    PTE 680 ------------------- 640 --------------------- 288 - 300
    PTE 780 ------------------- 748 --------------------- 300 - 315
    PTE 880 ------------------- 840 --------------------- 420
    PTE 1000 ------------------ 940 --------------------- ???

    RC 550 -------------------- 550 --------------------- 180


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