[help needed] 1991 Miata NA6

[jpauten]

Hello! I'm new to this forum and was looking for some guidance for my Miata.

My plan is to eventually have a rusEFI-powered turbo Miata with closed loop boost control. I've ordered the Frankeso kit from eBay and I've spent the past few days going over the Github docs and reading some of the firmware source, but I have a few questions regarding sensors & wiring.

I'd like to use a GM 3.5bar MAP, WBO, some sort of potentiometer-style TPS, and I don't care about the stock sensors, I'm willing to modify/remove all of them. What would you guys recommend for the TPS? Will I need to modify the board in order for these sensors to work properly?

Thanks!
jpauten

[stefanst]

Hi jpauten!

Welcome to rusefi. Your project should be fairly straightforward. What are your power / boost goals? What hardware are you using? Any other mods to the engine?

The GM-style MAP sensors should work well. The cheap eBay/Amazon aftermarket units are a bit hit or miss apparently. I had a few that were not very repeatable. OEM would probably be best, but who has the money for that? If you could afford stock MAP sensors, you probably wouldn't be looking at rusefi. So, get two or three of the cheap ones and see where that gets you.

[sadfab] makes a 3D-printed adapter for a Kia TPS that plugs into the stock harness. http://sadfab.com/16%20VTPS%20bracket.html If I remember right, I had to modify my jumpers inside the frankenso to switch 5V source to the TPS, but that's the only required mod for the TPS.

If you're planning on running any type of serious boost, you will need bigger injectors though. Idle on a Miata with huge injectors gets a bit tricky, so you should get some quality injectors and not the cheap stuff from Ebay or old Rx7 injectors or the likes. FlowForce uses stock Mustang injectors rated at 640cc/min which should be good for 300hp or more (I got 250 out of them with room to spare). You can look here: https://goflowforce.com/

The stock NA6 ignition is also not known for delivering a strong spark, so you probably need to look into alternatives, if you go with more than maybe 8psi (I'm guessing here). LS1 coils are popular among the Miata crowd. Check [sadfab] again- they make a bracket for LS1 coils.

Any other questions, we're here to help.

[jpauten]

Hey! I appreciate the reply.

I currently actually have some injectors for this car, not sure about brand but they're 300cc and I bought them from the person who also sold me the turbo- a Mitsubishi 16b.

I don't have any specific power goals, but I'm aiming for probably 10-12 psi max as I don't want to touch stock internals. Hopefully I can get a decent power number after lots of tuning.

About the WBO- Whats the cheapest way to go with this? I have basic soldering skills and I can make my own if need be

[stefanst]

[...]About the WBO- Whats the cheapest way to go with this? I have basic soldering skills and I can make my own if need be

Spartan2 OEM https://www.14point7.com/products/spartan-2-oem will fit inside the frankenso case and can be wired internally. Use the center connector on the frankenso to connect to the WB. All you need in addition is the connector to fit the center plug.

[jpauten]

Okay, thanks for the info, this saves me a ton of time. I just got the kit in the mail yesterday and I've been working on it. I'll post an update once it's in my car.

[jpauten]

Also- about the coils. I have a set of coils from my old car, a BMW 335i, laying around. is there any way I could get these to work with rusEFI? They're the "smart" 3-pin coils, but I don't know if coil-on-plug coils are an option. Before they came out of the car they were making 400+hp so I think they will be good enough for my Miata haha

[AndreyB]

Many smart COPs are supported by by rusEfi but why? What problem are you trying to solve?

There is an opinion that batch mode is really pretty good.

[jpauten]

The problem is I have limited money to buy new coils and I have good ones laying around my house. I don't know how hard it would be to get this particular coil to fit on Miata plugs but I watched this video
where someone manages to get smart COP to work with this motor. Fabricating/obtaining the rail that holds the coils seems annoying but this sounds fairly straightforward as long as Frankeso can drive them.

[Simon@FutureProof]

I am pretty sure those coils are not smart and you would need an IGBT pack for them.

BMW coils have been 3 pin dumb coils for a long time now, they use the 3rd pin for the ground of the secondary coil via a shunt resistor to do ignition monitoring.

[AndreyB]

I watched this video

I hear the voice of @Old Grey that means great content.