I'm seriously beginning to consider going to Megasquirt for my Speed 3. There is a DBW CANBus kit that will allow me to retain the stock throttle body without having to fab up a throttle cable system. This would also require me to go full PI as MS can't handle direct injection. MS would give me the option of live tuning, auto tuning fuel cells, automatic data logging to an SD Card, a crap ton more inputs and outputs for expansion in the future, and it's relatively cheap. All the stock sensors should work minus that I'll need a GM IAT sensor and different MAP sensor. I have been tuning my Miata with MS for years and it's been a solid management/ECU. Plus I think the tuning process for AP is too slow and tedious. So my plan would be to first get a 2.5 motor, build the block and aquire the injectors and other things needed to swap. Hopefully it comes with the wiring harness otherwise I will need to find one in a junk yard. However I am curious if the Focus ST manifold will bolt onto the 2.5 head without an adapter plate. Or if it needs the adapter plate to properly space it from the cylinder head. My question for those making some serious power already (north of 500) on a DI/PI setup, what is the stock DI injector flow rate and what size are you running in the port side of it? I'd like to be able to run just 4 injectors to keep things simple. Any input is appreciated. This obviously isn't gonna be an overnight thing but something that will take me a while to accomplish. But if it works out and works well I wouldn't be opposed to making kits to do so. There is always the option of just using my current speed 3 motor with PI adapter to get it going sooner but right now the Speed is my daily until I get the small quirks taken care of in my Miata.
@Enki spent some time with this, it would be cool to have a smarter PI option but unless I was going full race car I would not want to ditch the OEM ecu. I am running 800cc injectors and made about 600whp, I was not out of injector. The DI system was fueling about 300 of that. I don't see any issue with running 4 - 1200's or 1000's as newer injectors and ecu's can handle that for DD use.
Also, if you stop spraying the DI injectors and just use them to plug the holes they will melt and cause lots of issues. You would need to machine plugs for the OEM DI holes.
The stock injectors are 1500cc but can only be open long enough to flow half of that, so consider them to be 750s. Edit: Let me know how the Megasquirt ordeal goes. If you're shopping for one, I happen to have two and a stim I'll sell.
@JohnnyTightlips I'd be running a non DI head if I go this route. I have heard of meltdown failures on non lubricated injectors. If I try to get the car running on PI alone now I'd set it up as a split system like y'all normally do until I go full PI and delete that side of the system. As for DD with Standalone and PI, I think it would be fine. I get 30 mpg with my Miata running 640cc injectors and a turbo since I got it dialed in. I think the hardest part was getting the idle dialed in but after that it was smooth sailing. I set my target AFR tables. Locked my idle cells, activated auto tune fueling on the easiest setting then slowly drove around. Then kept turning the setting higher till I got to hardest so it barely made changes. Once that was 85 percent dialed in it came down to making small adjustments until everything was fully on point. For boost control I use a generic 3 port MAC valve. It's literally the same thing Cobb sells but it's only 30 dollars. I'd like to see what their source for it is cause it looks exactly the same as my Subaru friends EBCS made by Cobb. What versions do you have? I'm looking at MS3 simply because it has the most options available in terms of I/O but more of functionality. I run MS3Pro on the Miata and it's great. I appreciate y'all letting me know the flow rates. I'd probably shoot for something over 1000cc.
Well, I can't find my other one but I did manage to find my MS3 Pro Ultimate, along with my Innovate wideband.
Anyone have any updates/ attempts on a mega squirt solution? Now that Cobb has locked down access to access tuner, it seems this would be a popular solution for those interested in doing away with DI.
Couple of things to think about here. 1. Removing DI means either welding up and reforming the head (risky) or replacing the head with a PI only head (which probably won't be compatible with our harness) 2. You're going to need to do either a lot of software or wiring work to get all the standard electronics in the car to work properly with the Megasquirt; either CANBUS reprogramming or replacing all the CANBUS things with ones that work with the Megasquirt. Either way, suckville.
