MSefi.com read only forum (Jan.15,2018)

Hi, Im new to Megasquirt, been watching from the sidelines for a while and Im impressed with what MS has to offer.

What Im inquiring about here is how well it will run my Subaru EA82 Turbo, it is the Series 2 system, with the hotwire MAF and optical Dizzy.

I have read this a few times : http://www.DIYAutoTune.com/tech_article ... _turbo.htm
It sounds like it went well, but I have read some comments from people who knew the guy that said that over time the system lacked funtionality and I am a little concerned about this with mine.

From what I have read it was something to do with the MS not liking subaru's optical pickup, which I have found pictured below:
(Top wheel is the OE Subaru one, Bottom wheel is a comparitive Nissan one)


I want to keep the engine management component setup mainly OE apart from adding closed-loop idle control, via the universal IAC valve DIY offer. The Subaru cold idle valve is terrible! I would consider using MAP instead of the MAF sensor.

Anyway, if anybody has some advice on this and which would be the best MS option to go for (MS2, MS3, Microsquirt) I would greatly appreciate it! Thanks in advance

That trigger wheel will work fine as a distributor but not for distributorless ignition. What functionality were you concerned might be lacking?

Thankyou for the reply.
Could you please go into a little more detail for me, as in what the extent of 'as a distributor' would be?
Why does the Nissan one have smaller inner slots, is it a higher resolution system?

Subaru_EA82_4EAT_AWD wrote:Thankyou for the reply.
Could you please go into a little more detail for me, as in what the extent of 'as a distributor' would be?

That would be the way Subaru used it from the factory.

Why does the Nissan one have smaller inner slots, is it a higher resolution system?

That is something only the engineers at the companies that built the ECUs could answer for sure, but I could take a guess. Nissan used the slot length for cylinder identification. I'm having trouble telling if Subaru has all the slits the same length, but if they do, it's possible they used one edge for running timing and the other edge for cranking timing.

I'll try and find out about the size difference of the slots,
What I meant by the 'extent of as a distributor' was will the system have full, effective control over ignition timing?

If the optical wheel cant be used as a trigger wheel for EDIS or similar, I assume the 360 slots dont get used by megasquirt?

Here are the settings from the 'How to Megasquirt your Subaru RX Turbo' article:


And this is a quote from that article, about the CAS signal:
"...we used this 12v source to connect one end of a 1k 1/4watt resistor to, and connected the other end to a bit of wire running to pin 17 of that same large connector, also shown on the schematic above. This is the 'TACH Pullup' which 'pulls' the Optical CAS sensors output up to 12v so that the MegaSquirt can read it properly. It's looking for a 12v square wave on the ignition input (TACH input--pin24 to the MS-II)."

Please bare with me, Im just trying to understand the system and the best way to set it up before I go a hundred miles an hour down the wrong path!

...Apparently one is longer and is 38degrees in length.
If that helps.

I could also pull a spare dizzy I have here down if more details are necessary

Subaru_EA82_4EAT_AWD wrote:I'll try and find out about the size difference of the slots,
What I meant by the 'extent of as a distributor' was will the system have full, effective control over ignition timing?

Yes.

If the optical wheel cant be used as a trigger wheel for EDIS or similar,

It can't, at least not with the present firmware. If there was enough demand, it is possible that MS3 could support triggering a distributorless ignition with it, but this seems like it would be a really small niche.

I assume the 360 slots dont get used by megasquirt?

They do not.

Here is a photo and dimensions of the EA82 trigger wheel:

The red mark is approximately where the cas pickup is when the rotor button is faced #1 wire.

I have read quite a few forum threads about the Nissan (similar) optical wheels not working too well, why is that? Would I run into that kind of trouble with this wheel?

Would it be better to use the DIY replacement 54mm 24-2+1 wheel and set the #1 tooth angle to suit the EA82?

If not, would you guys be interested in developing an EA82 specific wheel if you had a sample and the OE angles?

Thanks for your help!

Subaru_EA82_4EAT_AWD wrote: I have read quite a few forum threads about the Nissan (similar) optical wheels not working too well, why is that?

Too much angle between the trigger pulse and the time to fire the spark. This mostly affects cranking where the RPM can change abruptly.

Would I run into that kind of trouble with this wheel?

Would it be better to use the DIY replacement 54mm 24-2+1 wheel and set the #1 tooth angle to suit the EA82?

I'd try the stock wheel first. Our 54 mm (L28) wheel is known to work if you have problems.

With the above information on my car and what I want to do, which ECU would you recommend?

What trigger pattern would be used with the large window OE wheel?

thanks.

Subaru_EA82_4EAT_AWD wrote:With the above information on my car and what I want to do, which ECU would you recommend?

MS2 should be fine unless you want sequential injection.

What trigger pattern would be used with the large window OE wheel?

thanks.

No wheel decoding.

Okay, so would micro squirt suit as well?
And would it suit the DIY wheel if I add it later?

Also how does ms see #1 with no wheel decoding?

Subaru_EA82_4EAT_AWD wrote:Okay, so would micro squirt suit as well?

Yes.

And would it suit the DIY wheel if I add it later?

Yes.

Also how does ms see #1 with no wheel decoding?

It doesn't.

Ah ok, so please tell me if I'm correct here:
I'm guessing either the rising or falling edge of the slots are in even places around the 720' engine degree plane and that you set megasquirt accordingly, along with the degree offset from TDC,
Then it sees 2 equal compression TDC pulses, each 180 engine degrees apart, each rotation at which the would be a batch fuel and ignition event, because of the rotor button only the correct cylinder would get the ignition.
Am I on the right track?

Is 2 TDC pulses each cycle enough for effective ignition control?
What happens to the fuel between the compression stroke and the intake stroke, does it just sit in the port?

Thanks.

Yes and yes.