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-   -   Sequential COP questions & research (https://www.miataturbo.net/megasquirt-18/sequential-cop-questions-research-20111/)

kingofl337 04-29-2008 07:03 PM

Now this is a solution! Instead of buying a ubber expensive Miata CAS we just but an escort dizzy! Please tell me you tested this and it fits between the engine and firewall!

The_Pipefather 04-29-2008 07:53 PM

Not tested yet, but the height of both CAS is equal. But it likely won't work with the stock ECU.

Dan, I'm no electronics guru either, but its easy enough to make it work. You need to run extra wires from the MS, enable Spark Outputs C and D, and reconfigure your wheel decoder settings, but I still need to figure that part out. Will document everything as I go along. I don't see how things are different for 94-97, or on 99+ except for the latter's different crank angle signals.

Matt Cramer 04-30-2008 10:19 AM

Wheel decoder settings are pretty straightforward: Set it to a 4 tooth wheel, trigger A to 1, B 2, C 3, D 4, and set the returns to zero. If running wasted spark, set it to dual-distributor mode.

The_Pipefather 04-30-2008 10:31 AM

Matt, shouldn't it be:

Base Teeth = 4
Trigger Pos

A = 2
B = 1 (These are your PNP settings)
C = 4
D = 3

Dual Dizzy mode will fire A,C on one coil, B,D on the other coil. Assuming all stock wiring, ignitors and coils.

Zabac 04-30-2008 10:41 AM

Ok, I'm still hanging in there so far. The new wires I'm running from MS are trigger wires, correct? This would not be an issue for me. The issue is now, here, figuring out what goes where and what order I have them fire, but I am sure you will figure that out way before I start comprehending this. So, we are on the verge of breaking seq. ign. done pretty easily and cheaply? Awesome, I feel enlightened to be able to read this thread, let alone to contribute to it.

What Matt is saying, I think, is that since you have separate trigger wires for each individual coil (COPs) you can run it that order. 1-2-3-4 since you control each coil separately and are not running one coil per 2 cyl.

Joe Perez 04-30-2008 11:01 AM

Right. The two wires are trigger outputs, which will require you building a pair of extra output circuits substantially identical to your current two. If you're using the "book" mods, this would be a pair of 2N3904s wired up just like the LED drivers. (you can omit the actual LEDs)

I'm pretty sure that the wheel decoder would be set as Matt suggests, to base = 4, A1 B2 C3 D4, with second / none missing.
Reference: http://www.msextra.com/manuals/MS_Ex...l.htm#twotrigs and scroll down to
"Sequential COP
4cy ONLY"

Note that this example applies to a four tooth crank wheel with a separate cam sensor, so it assumes four pulses per crank rev.

Ben 04-30-2008 11:06 AM

Dope. :)
What year festiva?

The_Pipefather 04-30-2008 11:08 AM

A1 B2 C3 D4 is right for seq. COP, but I was talking about triggering the stock coils in wasted spark mode with the 4/1 CAS. Only reason I thought its A2 B1 C4 D3 was because the PNP settings are that way, just that you need to fire A & C, B & D together before the trigger counter resets.

Joe Perez 04-30-2008 11:12 AM

Actually, I think it's going to ultimately be determined by the mechanical constraints of the sensor. You can only mount it on the head one way, and with a certain amount of adjustment room. Seems to me that wherever the reset pulse winds up being relative to the engine at #1 TDC is going to dictate the decoder order.

The_Pipefather 04-30-2008 11:14 AM

Right, that's what I was thinking too.


Originally Posted by Ben (Post 249935)
What year festiva?

Not sure about the year. I think any year would work.

Splitime 04-30-2008 11:19 AM

Msns-extra doesn't offer up the ability to dial each cylinder's tune in does it?

Basically going this route would be to just take an extra firing outta the ignition system right? ie: removing the "waste" in wasted spark....

Joe Perez 04-30-2008 11:21 AM

No and yes.

Zabac 04-30-2008 11:26 AM

Basically, yeah, replace our CAS with Escort CAS since you need each cyl. to fire only once per revolution vs. our wasted spark of twice per revolution. Ignition pretty much stays the same, it only reads each revolution once now instead of twice, thats why we need two more trigger wires/circuits to fire ea. cyl. (cause now you have 4 individual trigger circuits/wires, one for ea. cyl.) once only per revolution.

Geez, I hope I make any sense here.

Splitime 04-30-2008 11:32 AM


Originally Posted by Joe Perez (Post 249950)
No and yes.

Wait, so ms1-extra code has the ability to tweak spark per cylinder once in sequential mode?

If so... that is usefull for tuning with! Do some egt logging per cylinder and even them out with spark!

The_Pipefather 04-30-2008 11:35 AM

No it does not have THAT capability. In other words, you cannot trim spark and fuel on a per-cylinder basis.

Joe Perez 04-30-2008 11:46 AM


Originally Posted by Splitime (Post 249959)
Wait, so ms1-extra code has the ability to tweak spark per cylinder once in sequential mode?

You misinterpreted my answer. You asked two questions:
A: Msns-extra doesn't offer up the ability to dial each cylinder's tune in does it?
and
B: Basically going this route would be to just take an extra firing outta the ignition system right?
The answer "No and Yes" would be interpreted as:
No, it does not offer the ability to dial each cylinder's tune, and Yes, going this route would be "to just take an extra firing outta the ignition system"

Braineack 04-30-2008 11:51 AM

what does straying away from wasted spark net you?

Zabac 04-30-2008 11:53 AM

colder operating temps of the coils thus better efficiency

The_Pipefather 04-30-2008 12:00 PM


Originally Posted by Joe Perez (Post 249963)
going this route would be "to just take an extra firing outta the ignition system"

And, as to why this is needed, you discharge the coils half as often compared to the present wasted spark setup so:

1) Your coils would last twice as longer (theoretically speaking).

2) You would have a lot more spark energy available and therefore, all of the spark energy available due to capacitive discharge can be exploited. In essence this would mean you can open up that spark plug gap even more.

Splitime 04-30-2008 12:04 PM

Hooray for not even being able to handle reading my own pseudo double negative question properly! :p


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