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Megasquirt 12a

Old 01-28-19, 12:16 AM
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Megasquirt 12a

Howdy, been searching up and down but haven't found hardly anyone who has successfully installed a megasquirt on a 12a. I have an MS1 v3. The 12a is in a Locost chassis so there is no existing wiring harness outside of the megasquirt. The car I believe is wired up and ready to go with the exception of programming the ecu and wiring in the wideband innovative 02 sensor. I will initially be using a stock distributor which I believe has mechanical / vacuum advance mechanism and stock coils. I understand the megaquirt will just be used to control fuel. I've never done any programming myself but after reading Aaron Cake's write-ups I think it's possible to get this going? I have a 2 injector setup.

Main questions surround what parameters need to change from what's outlined on the 13b here?

https://www.aaroncake.net/rx-7/megas...ProgramMS1.asp

Do I wire the injectors from the relay board separately from each other?

Would it be best to simply lock the distributor?

Thank you for any help. If I've overlooked these questions answered on the forum previously my apologies, most everything I've come across is 13b related with 4 injectors.

Last edited by spoolinboost; 01-28-19 at 12:27 PM.
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Old 01-29-19, 08:51 AM
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12a and 13b info will be interchangeable.
i have a megasquirted na 13b using 2 injectors. I can probably help you get going. My map may work for you also as a good starting point.

Do you want to use a distributor or have megasquirt do the spark?

im confused by your injector question. Each injector should have its own output wire from the ecu. The power can be shared.

i wouldnt put your fuel pump in the location pictured. Youll overheat it and or boil the fuel.

Last edited by mikey D; 01-29-19 at 09:50 AM.
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Old 01-29-19, 01:38 PM
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Super, thanks very much. A base map would be greatly appreciated. I'd probably start by using the distributor to control spark and just have the megasquirt do fuel until I get comfortable, is the a good route? Good catch on the fuel pump, I'll move it or build a heat shield.
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Old 01-29-19, 07:51 PM
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The distributor works fine. I wouldn't worry about locking the mechanical advance. I always preferred having it.

What size injectors are you running?
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Old 01-29-19, 08:07 PM
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I'm not sure if you can import my map but I'll share my imperfect table shortly I would also recommend setting all of the cranking fuel crap to zero to get started.

Does ms1 have a target afr table? I didn't see Mr cake mention one. No worries if it doesn't. What afr you want to tune for depends on if your pre mixing and what your doing with the car.

Cool project I always wanted one of these.

Your using tuner studio?
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Old 01-30-19, 06:01 PM
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Here is what my ve table looks like currently. The high load low rpm and low load high rpm areas arent as good as they could be but their not bad either.
The table export is also attached, not sure if you can upload it or not. Im sure someone will comment on the high values in 85-95kpa compared to 100kpa. Engine wants what it wants. I use a separate table for the idle areas 50 will probably be to rich if you use it for idle.
Its still a work in progress but hits my target afr's where its important.

Attached Files

Last edited by mikey D; 01-30-19 at 06:04 PM.
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Old 01-30-19, 08:20 PM
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Yep, using Tuner Studio, thanks for uploading the map, appreciate it. I'll check to see what injectors it came with when I bought the car, which size would you recommend? As far as I know it's a stock 12a.
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Old 01-31-19, 09:23 AM
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Mikey, do you have a ported engine? I'm surprised that your max load VE numbers keep increasing all the way to 8800. My stock 13B VE peaked at about 7000.
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Old 01-31-19, 06:06 PM
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Eagle It's mostly stock. It's a gslse 6 port with no sleeves or actuators. Scca street prepared rules say something like porting allowed only within 1 inch of mating flanges, I guess you could call it optimized ports. I'm using 50mm Ida style tb with 60mm velocity stacks.

My power never rolls over. It's still rising though almost flat at redline. I'm working in a project to lengthen the intake and see if I can move the peak down closer to 6500. It's my biggest complaint about my setup.

I would recommend getting some Injector Dynamics injectors. They have all of the specs you to plug into the ECU. No guess work needed. They used to make a smaller than 1000 injector that would work for you but honestly there is no downside to the 1000cc. It idles fine on the ms3 at least. I don't think you would want smaller than 800cc injectors.

Last edited by mikey D; 01-31-19 at 06:14 PM.
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Old 02-10-19, 08:31 PM
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We tried to start the car this weekend with no luck. We weren't able to get a tach signal from the negative side of the coil to tell the injectors when to squirt. The car has a distributor and traditional coils. Double-checked the board to make sure everything is correct and appears to be OK for this setup. Anyone gone through this?
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Old 02-11-19, 06:38 PM
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Are you using the stock setup with 2 coils?
do you have a way to verify signal off of that wire?
Got spark for sure?

Last edited by mikey D; 02-11-19 at 06:56 PM.
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Old 02-12-19, 08:02 PM
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Yes, using the two coil setup and have spark for sure. Not sure how to test coming off that - terminal but I'll look into it. Figured if it was getting spark then it should also be sending a signal.
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Old 02-13-19, 07:20 PM
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yah if you have spark there should be a signal.

there is a lack of info for fuel only setups. It seems you can only run batch injection with this method.
Set it to trigger from optical/dizzy, jump XG1-XG2. You'll probably need a 10K resistor in series with the coil input to prevent noise spikes but should be able to get it running and see signal without it.

Hope it helps

Last edited by mikey D; 02-13-19 at 07:40 PM.
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