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Thread: Removing multiplex from 7MGTE for less than $200

  1. #1
    Grease Monkey

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    Default Removing multiplex from 7MGTE for less than $200

    Note: This was originally posted to the AEM forums as a means of removing the multiplex igniter when using the 30-1110 PnP EMS. However, it is a good solution for a 3 channel igniter for many standalone systems.

    First, some background:

    I have a built 7MGTE swapped into a Mk2 supra, and had been running on the stock computer/electronics adapted to work in the A60 chassis (with everything including the twin speed pump control and a tach adapter to use the 7MGTE tach signal with the mk2 tach installed). A few weeks ago I took the plunge and installed the AEM EMS. I am using the GM IAT and MAP sensors to run speed-density. As a side note, I have been using the 2JZ-GE waste fire coils which mount on top of 3 of the plugs and have short plug wires to hook up to the other 3. The plug is identical to the stock igniter, and the dwell etc. is close enough to run just fine, at least on the stock electronics.

    After I got the car running, I had to fiddle around endlessly with the coil dwell settings to minimize the misfire I was getting from the stock igniter due to the multiplex issues, but they never completely went away. I was looking at ordering the AEM CDI ignition, but was loathe to spend the money since I already have a HKS TwinPower box.

    So I did some research, and found out that the igniter from the same setup as the coils I am using (98 and later 2JZ-GE) is a pretty standard 3 channel smart igniter with the correct tach output to drive the 7MGTE tach - it is called a 'DH61 igniter'. Turns out that Toyota figured out that multiplex was a bad idea, and hasn't used it since the 7M.

    After a discussion on the phone with AEM tech supprt, and a couple hours with EWDs for the 7MGTE and 2JZ-GE 'donor', I figured out how to made an adapter harness using the two plugs off a 7MGTE igniter, and the big 10 pin plug from the 2JZ-GE igniter. The only 'extra' wire is one that goes from the 10 pin to ground, and in some cases, the 10 pin plug only has 9 wires as it is from a car without a tach, which means you can either install another molex style pin and cut a hole in the rubber plug, or just move the wire and connector from IGf on the ignitor, since the AEM computer ignores this pin. I am including wire colors for the IS300 and GS300, although you will notice the pin positions are identical for all DH61 igniters. This fix, including the wiring postions and colors on the body side, is identical for all years of 7MGTE.

    As a side note, this will NOT fix misfiring issues related to a bad CPS - watch the 'sync errors' field in the cam/crank parameters as you drive (and get misfiring) and make SURE it is not incrementing. I also reccomend a MAP sensor that is NOT mounted to the manifold, as this causes a very 'dirty' signal that can also cause running issues.

    You can get the igniter and plug from Toyota ($$$) or from a wrecker. I picked one up, with the plug and some wiring, from a wrecked 2004 GS300 for $150 CAD.


    On to the wiring:

    Body Plugs____________________________________DH61 Igniter

    4 Pin Input____________________________________10 Pin(GS300)_________10 Pin(IS300)
    IGf (Not required)__LG-B__Pin Position #1___->____IGF__B____Pin Position #4__B-L
    IGt (Coil #1)______LG____Pin Position #2___->____IN1__B-Y__Pin Position #7__GR-B
    IGdB (Coil #3)_____L-W__Pin Position #3___->____IN3__B-R__Pin Position #5___B-Y
    IGdA (Coil #2)_____L-B___Pin Position #4___->____IN2__B-L__Pin Position #6___B-R

    6 Pin Output
    Coil #2 Out_______L-Y___Pin Position #1____->____C3___B____Pin Position #2__G
    Coil #1 Out_______L-R___Pin Position #2____->____C2___B-R__Pin Position #1__B-R
    +12V/Coil Common_B-O___Pin Position #3____->____+B___B-W_Pin Position #9__B-W
    Coil #3 Out_______Y_____Pin Position #4____->____C1___W___Pin Postion #10__B
    Tachometer Out___B_____Pin Postion #6____->____TAC__B-Y__Pin Position #8__N/C
    ______________Wire to good ground point___->____GND__BR___Pin Position #3__BR


    For the 'Pin positions' and wire colors, remember for the DH61 igniter plug they are looking from the open end of the plug, numbered left to right with the 'clip' at the top, and for the 7MGTE ignitor plugs they are for the MALE connectors of the ENGINE HARNESS on the 7MGTE, reading left to right, then the next row down left to right, again with the clip at the top, looking at the open end of the plug. This means for the ignitor plugs (female side) you read the plugs from the back end (where the wires come out) again from the left to right, then the next row down, ignoring the wire colors on this end. Or you can use the male side as a reference, or both. Coil #1 is cylinders 2&5, Coil #2 is 3&4 and Coil #3 is 1&6.

    You can refer to the mk3 TSRM for the plug positions /mk3 wiring here
    http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=40
    http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=41

    The plug on the DH61 is really easy, just remember 1-10 from left to right facing the open end of the plug. It is often numbered on the wiring side anyways.

    And don't forget to ground the brown wire to a good grounding point - I grounded it to the same point as the HKS TwinPower. As a side note, any ignition amplifier (like the TwinPower) can be left in place, wired as it was before. Unless you have a CDI system that can operate as a stand alone igniter, in which case I reccomend you wire that up directly to the ignitor inputs/outputs as per its instructions, so you don't need to use the DH61.

    I mounted it using a M6 capscrew to one of the stock ignitor mounting holes - had to drill out the mounting hole in the DH61 a tiny bit.


    AEM software setup:

    -Enable Coils 2 and 3, check off both knock inputs
    -Using the Dwell wizard, select '93 - 98 3.0 non turbo'
    -Disable Multiplex ignition
    -Set Cam/Crank spark teeth to 12
    -In Ignition phasing, set IGN Tooth #1 = 0.5, #2 = 4.5 and #3 = 8.5

    EDIT JULY 2017
    As per my post on page 18, my DLI died and I looked up some better dwell data, as it is actually a dumb igniter. I found ideal dwell for the coils is 3.6ms, so after selecting the dwell wizard as above, under dwell options change;
    -Dwell factor to 18
    -max teeth to 3.6

    This gives you 3.6ms dwell to 5000 RPM and dropping after that (2.6 at 7000 RPM) which works really well.

    Also you can set ignition phasing at 0, 4 and 8 teeth (0 for the coil driving 1&6, 4 for the coil driving 2&5 and 8 for the coil driving 3&4) as long as you then adjust the overall phasing up 0.5, or just do the timing setup wizard again with a timing light.
    END EDIT

    At this point the engine should start as it did before - don't forget to double check your base timing.


    Results:

    The missing is completely gone, and the car feels smoother thru all rev ranges. I don't know if this is a result of using an igniter 'matched' to the coils I am using, or due to the elimination of multiplex - but I can tell you that no matter the coil type (7MGTE or 2JZGE), this 'fix' WILL eliminate misfiring due to the multiplex system. It also operates the stock tach properly, and does not require rewiring of the coil harness, or 'hacking' of the engine harness - just a couple plugs with wiring from the old igniter, and the new igniter with plug and wires.


    Toyota part numbers:

    89621-30020 - Igniter
    90980-11653 - Housing, Connector
    82998-12440 - Terminal, Connector (each, you will need at least 9, 10 if you are picky and want to wire up IGf)
    Last edited by Funkycheeze; July 21st, 2017 at 02:26 PM.

  2. #2
    I play with fire
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    Default Re: Removing multiplex from 7MGTE for less than $200

    I assume this will only work with a standalone?
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  3. #3
    Grease Monkey

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    Default Re: Removing multiplex from 7MGTE for less than $200

    Yes. If you do this with the stock ECU it will only fire on 2 cylinders.

  4. #4
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    Default Re: Removing multiplex from 7MGTE for less than $200

    Multiplex Ign sux major ass.

    Gixxer and i have been discussing this and then i saw this thread. I got a gs400 ignitor i think, a DH62. Actually is a DS 62 and works fine. Aholes at the junk yard charged me $50 with pig tail. it does not have a tach wire. i put a AEM large pin in the hole with a wire. the DH 62 has different color wires coming out of the ten pen (9 used) and i had to convert the wire colors over. the pins do the same thing just different wires colors. i also took a 7M ignitor apart and the wires are labeled in the 7M ignitor so i could convert those colors too. I then made a jumper harness with the 10 pin and the cut off 6 pin and 4 pin 7M ignitor plugs. i used the above numbers to convert my aem map from multishit to smooth ingintion and reset timing.

    It idles smoother and runs smoother. i do have a boost problem now tho. may be my clutch slipping or my wg duty &#37;. installing the ignitor wizard may mess with the aem program and i dont know it. I will see..

    edit: found out i had cut the power wire to #6 when converting to sequential at same time and that was my miss and stubble problem. I also probably wired the harness wrong but when i fixed it i still had a miss from a undiagnosed #6 injector with no power. all fixed now and is an amazing difference.

    Every mk3 owner with an AEM or other standalone should go sequential injection. also getting rid of multiplex is awesome. i still have 7m coils but will go cop soon.

    DS62 or 61 ignitor is a must mod for any mk3 AEM car.
    Last edited by Halsupramk3; July 25th, 2009 at 10:22 PM.
    Hal
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    Finally running again after 3 years.

  5. #5
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    Default Re: Removing multiplex from 7MGTE for less than $200

    funkycheeze

    you stated
    "AEM software setup:

    -Enable Coils 2 and 3, check off both knock inputs
    -Using the Dwell wizard, select '93 - 98 3.0 non turbo' - as it is a smart coil this constant dwell works best."

    when you say check off both knock inputs you mean off as in has a check mark there or are left unchecked?
    thanks
    Hal
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    522+ rwhp
    Finally running again after 3 years.

  6. #6
    The quiet one
    bfr1992t's Avatar
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    Default Re: Removing multiplex from 7MGTE for less than $200

    Wow, great work FC! This has been on my long list of shit to do but I've been obsessing on going to 6 channels/coils and attempting to use Inj #10 "as coil".

    For the GS300, assuming it has to be a second gen '97-05 to get the distributorless 2JZ.

  7. #7
    Grease Monkey

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    Default Re: Removing multiplex from 7MGTE for less than $200

    Yes, It needs to be a 2JZ-GE with the distributorless waste fire ignition, so from '98 onward.

    And for the knock inputs, I mean check the boxes, as in you need to enable the knock correction for all 3 coils instead of just coil 1

  8. #8
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    Default Re: Removing multiplex from 7MGTE for less than $200

    for the 6 pin connector its pin position 1 is coil #2 output and this corresponds to the dh61 C3 on position #2. then 6 pin of the 7m position 2 is coil #1 and this corresponds to the dh61 C2 on position #1 pin. then 6 pin connector pin 4 is coil #3 and corresponds to C1 on pin 10 on the dh61. what are C1, C2, and C3 on the dh61 vs the 7m ignitor coils and why dont they have the same numbers as in coil #1 is C1 and coil #2 is C2 etc.
    whats the deal?
    Hal
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    522+ rwhp
    Finally running again after 3 years.

  9. #9
    Grease Monkey

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    Default Re: Removing multiplex from 7MGTE for less than $200

    Quote Originally Posted by Halsupramk3 View Post
    for the 6 pin connector its pin position 1 is coil #2 output and this corresponds to the dh61 C3 on position #2. then 6 pin of the 7m position 2 is coil #1 and this corresponds to the dh61 C2 on position #1 pin. then 6 pin connector pin 4 is coil #3 and corresponds to C1 on pin 10 on the dh61. what are C1, C2, and C3 on the dh61 vs the 7m ignitor coils and why dont they have the same numbers as in coil #1 is C1 and coil #2 is C2 etc.
    whats the deal?
    It's because the coil numbering procedure vs. the actual cylinders fired by that coil differs between the two systems. You can certainly wire it up C1 - coil 1, C2 - coil 2 and C3 - coil 3, but then in the AEM setup you need to set tooth 1 to 4.5, tooth 2 to 8.5 and tooth 3 to 0.5

    I found this out the hard way when I made the adapter harness the first time.

    In the 7M, coil 1 = cyl 1 & 6, coil 2 = 2 & 5 and 3 = 3 & 4 as they are numbered left to right on the coil pack 'bracket'
    for the 2JZ-GE, coil 1 = cyl 2 & 5, coil 2 = cyl 3 & 4 and coil 3 = cyl 1 & 6 as they are numbered front to back on the engine, and the coils are mounted on cylinders 2, 4 and 6 respectively.

  10. #10
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    Default Re: Removing multiplex from 7MGTE for less than $200

    ah, i was suspecting that. i guess one could also say that coil 1, 2, and 3 are the same it is just that toyota plugged different plug wires into each one for the 7M. you could rearrange the plug wires on the 7m to a different located coil if it was wired wrong as the ignitor really does not know what set of plugs is going off. of course thats a guess on my part and can be wrong. still a lot to learn about ignition calcs.
    Hal
    90T

    522+ rwhp
    Finally running again after 3 years.

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