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Old 11-21-2007, 02:44 PM   #1
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Default Integrating Megasquirt into stock ECU case

Hi all,

I've been hunting for a good place to ask this question, and seeing the expertise that all you guys here have with MS on a miata, I think there isn't a better place than this.

Here's the situation. I'm planning to autocross my nearly-stock 92 NA next season in STS2. For those of you who dont know, this is an SCCA class which allows you to do basic engine mods like intake and header. The suspension mods allowed are much more open.

The class allows one to use a modified ECU, provided you use stock case, sensors, and wiring. . The following is the exact wording from the 2007 rulebook:

Quote:
1. Reprogrammed ECU may be used in the standard housing. Traction control parameters may not be altered. Altered engine controllers may not alter boost levels in forced induction engines.

2. Electronic components may be installed in-line between an engine’s sensors and ECU. These components may alter the signal coming from the sensor in order to affect the ECU’s operation of engine management system. Example: fuel controllers that modify the signal coming from an airflow sensor.
My plan is to get all the other stuff like intake, headers etc. and then try to integrate MS into the stock case, using the stock connector. Sort of like a PnP. This is legal since the rules do not specify if the function of the "reprogrammed ECU" is performed through a change of hardware, or software.

I want your advice on some issues that I foresee with my limited MS knowledge:

1) What hardware I should be buying to make this happen. MSI, MSII, or microsquirt? I'd like to spend as little money on this as possible because the suspension is going to eat a lot of the budget.

2) Can the stock barndoor AFM be made to work with either of these, and not use a MAP at all?

3) What about wiring? Can it be kept as near to stock as possible?

4) Any other issues you guys foresee?

(oh BTW, I did do a search and found this thread: https://www.miataturbo.net/showthrea...light=ECU+case
Its just that the OP didnt follow up on what happened with his plans)
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Old 11-21-2007, 02:46 PM   #2
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If i read those rules, I don't see why a MS couldn't be run as a piggyback.
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Old 11-21-2007, 02:49 PM   #3
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Those were my thoughts exactly, but I will have to clarify that with one of the members of the exec. committee of the SCCA that makes those decisions. I am posting a thread on miata.net right about now.
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Old 11-21-2007, 02:59 PM   #4
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Do that first and then reinvent the wheel. Worst comes to work you rip out the guts of the factory ecu and shoehorn the megasquirt in. If the dimensions of the case are the same or larger I dont see why it would be hard.
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Old 11-21-2007, 03:03 PM   #5
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I mean, technically MS is just an electronic device installed in-line between the harness and ECU.
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Old 11-21-2007, 03:03 PM   #6
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I don't see why it wouldn't work... the V3 assembly is not as tall as the V2.2. I think you could get it in the case with room to spare. Just leave off the DB9 and DB37 and run the chassis wiring to the stock connector via standard wiring. Dremel out an appropriate sized whole in the case for you DB9 and do the same for it.
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Old 11-21-2007, 03:52 PM   #7
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After seeing the guts of my PNP, I don't see why it couldn't fit inside a stock case if (1) you hand wire the main board to daughter board instead of using the serial cable and (2) fit the map sensor externally.
I assume your rule book says the AFM must remain in place. If so, can you simply secure the flapper in the full open position?

Also, I'm sure you realize that the MiataLink fits inside a stock case perfectly (by design).

You may wish to email DIY Autotune. Many months ago, Jerry was telling me of potential plans to fit a MS board into a stock case for a well known racer, and he said he had "several ideas" as I recall.
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Old 11-21-2007, 04:11 PM   #8
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Braineck, your point that MS can be used as a piggyback (though technically it wouldnt be one) is probably on the fringe of illegality because MS would be sending signals *back* to the sensors, and not just *altering* them. I dont want to be in that position.

Arkmage & Ben, I see what you guys are saying about the DB9 & DB37 connectors.

However, MAP is not legal. I would have to run the stock AFM while retaining its functionality.

Can MS be made to work with the standard AFM, i.e, without installing a MAP sensor?

Does it matter which MS to order: 1 or 2?

I am also on the lookout for a stock 90-93 ECU case because I want to be able to switch back if something goes wrong. If anyone has one lying around, please do let me know.

I will also take DIYautotune's opinion on this.
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Old 11-21-2007, 04:19 PM   #9
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you can run with the stock AFM, but the MS still need to read the MAP signal.
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Old 11-21-2007, 05:39 PM   #10
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Quote:
Originally Posted by Braineack View Post
you can run with the stock AFM, but the MS still need to read the MAP signal.
or you could just use the AFM like the stock ECU does

http://megasquirt.sourceforge.net/extra/MAF_Stuff.htm

you could then use the MAP sensor for barometric correction
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Old 11-21-2007, 05:46 PM   #11
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The larger connector on the MSPNP - and some other features - make it a bit too large to fit in a stock Miata ECU case. We thought about it, but it's not going to go there. On paper, the Microsquirt has what is needed to make this work (two spark outputs, two spark inputs, and MAF capability), although I have not seen it done yet.
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Old 11-21-2007, 06:27 PM   #12
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Quote:
Originally Posted by The_Pipefather View Post
Braineck, your point that MS can be used as a piggyback (though technically it wouldnt be one) is probably on the fringe of illegality because MS would be sending signals *back* to the sensors, and not just *altering* them. I dont want to be in that position.

Arkmage & Ben, I see what you guys are saying about the DB9 & DB37 connectors.

However, MAP is not legal. I would have to run the stock AFM while retaining its functionality.

Can MS be made to work with the standard AFM, i.e, without installing a MAP sensor?

Does it matter which MS to order: 1 or 2?

I am also on the lookout for a stock 90-93 ECU case because I want to be able to switch back if something goes wrong. If anyone has one lying around, please do let me know.

I will also take DIYautotune's opinion on this.
Unless you honestly think you will make it to regional or national level just cheat. The odds of them checking you car for an ecu are slim to none at local level, and pretty low at regional.
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Old 11-21-2007, 09:19 PM   #13
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open ecu rule was just passed for IT - you'd think solo would just follow the lead and simplify things. IMO the "oe case" rule is just stoopid.
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Old 11-21-2007, 10:20 PM   #14
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Quote:
Originally Posted by m2cupcar View Post
IMO the "oe case" rule is just stoopid.
You can say that again. The Honda guys get a distinct advantage with this rule because they use MAP from the factory, and the **** of it is that the most restrictive part in the Miata intake is the AFM.

While its definitely tempting to be illegal, I think there's one way to retain MAF and be legal: use an external MAF sensor to input into the megasquirted stock ECU case, and retain the AFM, but dont do anything with that signal. The rule doesnt say that the ECU has to use the AFM signal. I'm presuming this is possible.
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Old 11-21-2007, 11:17 PM   #15
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the AFM signal gets provided as the flapper door opens and closes.

any chance you can put the electronics of the AFM into a larger housing, like the 626 or Rx7?
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Old 11-22-2007, 01:16 AM   #16
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I dont think so. But I dont see why the pipe connecting the throttle body and the AFM cant be made larger. I think the word I'm looking for is "plenum".
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Old 11-22-2007, 02:14 PM   #17
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Ok there is another solution in sight. Alpha-N control. Since it uses only TPS and RPM, it should be doable. What do you guys think?
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Old 11-22-2007, 03:44 PM   #18
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It's do able though none of us use it. Some of the ITB users use alpha-n. It's pretty useless with turbo cars.
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Old 11-22-2007, 05:05 PM   #19
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Here's a question. WHY would you want to do this? I could understand it if it were possible to remove the AFM, or if you had engine mods that would need the amount of control a standalone would give you. But since you can't, why bother?

Use an emanage to take care of timing and to tweak the fuel. Do the crystal mod to the existing ECU to raise the rev limit (if necessary). Call it a day.

If you went this route I doubt you'd be giving up much power to a full standalone given the restrictions of the class.
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Old 11-22-2007, 05:07 PM   #20
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Quote:
You may wish to email DIY Autotune. Many months ago, Jerry was telling me of potential plans to fit a MS board into a stock case for a well known racer, and he said he had "several ideas" as I recall.
I imagine that would be Andy Hollis ... who ironically is somewhat responsible for the STS rule set and removing the ambiguity from the rules that allow replacement of the AFM.
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