Subaru 4-pin logic coil setup?

[Two_Wheeler]

I'm looking to install a 4-pin logic level input coil from a circa 2000 4 cylinder Subaru on my GS1000 bike project w/ 24-2 crank trigger. I saw a post here that referenced using one and having MS settings of "going low", with an allegation that had been discussed on this forum. I read through 3 pages of search results here and could not find any such post. I have attached a PDF of my proposed wiring diagram.

I was considering using the VW 106B coil, but the plug wire outputs may be too tall to fit under my tank vs the 90 degree terminals on the Subaru coil.

My question then goes to setup- do I set this up as going low or going high?

Subaru_logic_coil_GS1000.pdf

Proposed wiring diagram for Subaru logic input coil

(13.99 KiB) Downloaded 132 times

[valqk]

First of all. Schematic in the pdf is wrong, at least for the Cyl. numbers, because this is the correct cyl. numbering in Subaru and each output goes straight to the cylinder so numbering on the coilpack is the same as the numbering of the cylinders.


Best will be to check Subaru manual for specific year/part number you've got.I think it's 4 pins coils only pack and needs igniter or transistors in mega to drive high current coils...
I'd prefer going with OEM igniter - easy to use and just wire it and go. You can always get it from a junkyard. Heard of failed ones... maybe once or twice in 10 years... + you keep high current out of your mega.
If you need manual PM me.

[Two_Wheeler]

Thanks for the reply. My Suzuki does not have a Subaru engine in it, so cylinders (1 & 4) (2 & 3) each fire in wasted spark, which is why I wired it as shown on the PDF. This is the same thing as the Subaru (1 & 2) and (3 & 4) electrically- each coil is firing two cylinders. I used a multimeter and identified the spark plug terminals that were common, and I labeled the coil for 1-4 and 2-3.

As far as an "ignitor", isn't one built-in to the circa 2001 4-pin coil? I shopped for an "ignitor" or anything similar on Rock Auto and the only thing they sell is the coil I already have.

The diagram linked here is from a 2001 Forester, and it only shows an "ignition coil and ignitor" as far as an ignitor goes. The wiring is the same as what I have as well:
1. Coil 1 from ECU
2. Power in
3. Ground
4. Coil 2 from ECU

My main concern remains interfacing this coil with MS settings, e.g. going high vs going low.

Here's a screencap of the 2001 Subaru diagram:

2001 Forester engine electrical diagram with coil

2001_Forester_Electrical.jpg (95.61 KiB) Viewed 1645 times

[valqk]

If the igniter is built in, this means you can try to test it if it requires gnd or vcc to drive it.
Try putting 1k resistor to driving pin. Connect the +/- power pins according to the manual. Connect wire and sparkplug with connected gnd to the sparkplug.
Then power up the coil and with a simple wire try to quickly touch and release the 1k open end(where the ms should be connected to). Do not hold it for long time connected. You should see a spark when connecting/disconnecting.
If nothing happens, try pulsing 1k to the +5v. If nothing happens to +12v.
That way you will see if you need low/high signal.

This method might not be very good but it's easiest and simplest and I would test it like this.
BE VERY CAREFUL not to hold 1k driving wire connected for too long!!! You might burn the coil! Simply touch it by moving wire for miliseconds trough leg of 1k driving resistor.
Also use a fuse for powering the coil (just in case).
I hope that helps.

[Two_Wheeler]

Thanks for the info. I'll give that some thought.

[Two_Wheeler]

According to this thread, the proper setting for the 4-pin internal ignitor coil I have is going low:

1. The Subaru coil FH0137 fires when the signal goes LOW. So the "normal" setting is correct - not inverted...

2. The pinout is as such:
Pin 1 is the 5v input that fires the "1-2" coil
Pin 2 is 12v
Pin 3 is Ground
Pin 4 is 5v input for "3-4" coil

The Subaru manual that specifies 0.73 ohm across pins 1&2 and 2&4 does not seem correct. My coil measures open circuit, yet operates properly. There does seem to be some capacitance and diodes within the ignitor module.

So at least for my settings, "going Low" for spark output seems right, and the pinout above is correct.

[jsmcortina]

No, that's potentially bad information.

As far as I know, ALL logic coils charge (dwell) on the high edge of the signal and fire on the low edge.

The high/low setting depends on the way you customise the output. You need to take that into account.

For the "FET method" or MS3X outputs, "Going High" is the setting to use, this means the signal going high starts the dwell.
For the not recommended "transistor/resistor method" you have to use "Going Low".

However... read the manual.

James

[vc10786]

Did you ever get MS working with your Subaru coils?

I got my hands on a couple coil packs(part number FH0362, Diamond brand) which I believe are identical to yours. I plan to use them with a Microsquirt application.

After looking around online I found a Subaru 4-pin coil testing procedure which calls for measuring the resistance between the pins. This is wrong!! It does not work on the igniter type coil packs!

Even though they appear exactly the same, the integrated-igniter coil packs cannot be tested in this manner due to the integrated circuitry. The pins are not connected to the primary windings so there is no resistance test to be done here. The 4 pins are connected to the integrated coil drivers which show infinite resistance when probed, so ignore the instructions floating around the web that say you should show .73 ohms here. If you have the integrated-igniter type coil packs, you will not get any such reading here.

So basically I found the proper way of wiring it up, but only after a whole day of sorting through lots of incorrect information online. Don't trust the wire colors/pin arrangements/or even the official testing procedures for these coils. You need to have a 5v+ source available to trigger the logic pins for the integrated igniters, something which almost nobody makes mention of. Here is a proper pinout diagram I have put together for posterity:

Subaru Coil Pinout.jpg (525.31 KiB) Viewed 1545 times

[Two_Wheeler]

Thanks for the info. I have not worked on that project in a while due to more pressing repairs to daily drivers, but keep meaning to get back to it. Your post is most helpful. I still need to determine MS low or high settings for it.

[jsmcortina]

I still need to determine MS low or high settings for it.

See my post above.

James

[Vbugmanw]

Thank you for providing the pinout on this coil! I have used this thread as a guide for my installation and am having an issue with half of the coil not firing. I am using an Amp’d microsquirt with the coil discussed in the thread above. I am not getting spark from half the coil. The half of the coil controlled by the IGNOUT 2 is not firing. Do you have the dwell and other settings you used in TunerStudio, that I could use to compare to mine? I am wondering if I burned the coil/ignitor or if perhaps I just got a bad coil out of the box. I am struggling to figure out the issue and thought someone here may be able to help.