Removing multiplex from 7MGTE for less than $200

[Funkycheeze]

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/Library/TEWD/MK3/manual.aspx?S=Main&P=40
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?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)

 

[Poodles]

I assume this will only work with a standalone?

 

[Funkycheeze]

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

 

[Halsupramk3]

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 %. 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.

 

[Halsupramk3]

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

 

[bfr1992t]

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.

 

[Funkycheeze]

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

 

[Halsupramk3]

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?

 

[Funkycheeze]

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.

 

[Halsupramk3]

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.

 

[Funkycheeze]

Yeah you could move the plug wires around but some might be a little long or short, so it wouldn't look as neat.

I'm also using the 2JZ-GE wastefire coils that sit over 3 of the plugs, so I had to wire it up as above.

 

[X-man]

I priced one of these ignitors through Advance Auto and new they weren't but 298.00 which still isn't bad when you consider having to spend 50.00 for an MSD tach adaptor to other ignitors.

 

[Halsupramk3]

so your original set up post is for how you wired the 2jz ge cop plugs with COIL physical order of c1=2 & 5, c2=3 &4, c3=1&6 you wired in 7M ignitor 6 pin plug to 10 pin DH plug as follows

coil #2 plug output to C3 pin #2 on the 10 pin ignitor DH 61 or DH 62
coil #1 plug output to C2 pin #1
coil #3 plug output to C1 pin #10

this requires an ignition phasing setting coil option 1,2,3 on with both knock 1 and 2 check marked and
ign tooth#1 is 0.5, coil 2 ign tooth is 4.5, and ign 3 tooth is 8.5 and the car runs for 2jz ge cop waste fire coils which are physically installed in the different order labeled above. the physical order being different from 7m coil pack is not something i initially picked up on and that did cause problems in ignition phasing. (car runs like crap)

FOR 7M COIL OEM PACK which has a phisical order of c1=1&6, c2=2&5, and c3=3&4 then i can wire into the ten pin DH61 or DH62

coil #1 plug output to C1 pin #10 on the 10 pin DH ignitor
coil #2 plug output to C2 pin #1
coil #3 plug output to C3 pin #2

am i correct as
this requires an ignition phasing coil option of 1,2,3 on with both knock 1 & 2 check marked and
ign tooth #1 is now 4.5, coil 2 ign tooth #2 is now 8.5, and coil 3 ign tooth #3 is 0.5?

this would make the pins all match as if stock of c1 to coil 1 etc and have the correct firing order in the aem?

currently i have my 10 pin to 7M 6 plug and 4 plug wired as yours is (coil #2 = C3, coil #1 = C2 etc) and using the original Ignition phasing inputs and it runs like crap. i will change ignition phasing to c1 is 8.5 which you mentioned earlier and probably wire it in later as c1= coil #1 etc and change the ignition phasing inputs as required.

what you think?

 

[Funkycheeze]

Too much confusion!

Ok, for the guide I posted on the first page, The coils are as follows:

Coil 1 = 2 and 5
coil 2 = 3 and 4
coil 3 = 1 and 6

So it makes no difference if you have the stock 7M coil packs, or the JZ waste fire COP setup. You still need to wire in the way I first described, and then set coil 1 tooth = 0.5, coil 2 tooth = 4.5 and coil 3 tooth = 8.5.

If you want to wire C1 -> coil 1, C2 -> coil 2, C3 -> coil 3, then you need to set coil 1 tooth = 4.5, coil 2 tooth = 8.5 and coil 3 tooth = 0.5.

Dont forget to change 'spark teeth' under the cam/crank sensor options to 12!

Frankly, If you first wired it as I described in my post and set the AEM as described, it should run. Messing around with the tooth values after that will just cause it to not run at all. Make sure you check your base timing!

The wierd numbering order for the waste fire 2J coils only applies to the 2J wiring diagrams - building the adapter harness as described gets everything back to 'normal' for the 7M.

 

[X-man]

I set mine to run off of 24 teeth. It runs fine with no issues, but a map I got from John Reed one time had it set to run off of 12 teeth. Either way will work fine, you just have to have your settings right.

 

[Funkycheeze]

Yep - the ignitor numbers 4, 5 and 6 duplicate 1, 2 and 3 so you go:

24 teeth for ign.

tooth 1 = 0.5
2 = 4.5
3 = 8.5
4 = 12.5
5 = 16.5
6 = 20.5

ez!

 

[TurboStreetCar]

Is this only for an aem? Or would this help out a stinger, or mega squirt or other standalone car aswell?

 

[Funkycheeze]

Will work with any standalone that can control a standard 3 channel igniter. In fact, I'm pretty sure the MS and/or Stinger units require a different ignition setup as they are totally unable to properly communicate with the stock multiplex igniter.

For the MS system though, the Ford EDIS modules are best.

 

[TurboStreetCar]

How do you know how much dwell to set it for?

 

[Funkycheeze]

The DH61 igniter sets the dwell automatically based on RPM. You just need to supply it with the ignition input pulse for each channel. You may need to fiddle around with the static dwell time for the outputs of the ECU to get it to run properly - I figured it out for the AEM box.