Is it possible to have an ECU switch
 

Our engine builder was getting squeamish about EPA violations and doesn't want to work on our car because it has a MegaSquirt. Otherwise, we have to sign something that says it will never be registered for road use. Well when we bought the car it was already modified and we have not done anything to make it worse. It has a catalytic converter etc. It's not going to be used as a daily driver but will need to be registered because we don't have a big truck to pull it to the track.

Is it completely ridiculous idea that a Miata stock ECU could keep a car basically running without changing field injection etc. So that it could be switched to the high-performance ECU once it arrives at a track.

Thanks in advance for the ideas.

Probably not - unless you tune it on stock injectors.

What year Miata, what mods do you have and what kind of work is your engine builder doing? It might be possible to simply physically swap the MegaSquirt for the stock ECU at the track, but that may not be possible if your mods aren't compatible with a stock ECU.

some people put their cars back to stock for emissions testing....others buy "stickers" from "reputable" places....find a new "engine builder" that "follows rules"

Engine "builder", or engine "tuner"?

In my mind, a builder puts together the pieces regardless of the ECU that's going to run it once it's built. That shop MIGHT be squeamish about putting pieces into that engine that are not EPA-approved for road use and might require you to sign a release stating that the engine won't be used in a vehicle driven on the street. What you do with that engine is up to you ("Golly officer! How did THAT get in THERE?!!"). You're accepting liability for any mis-deeds

A tuner, on the other hand takes your built engine and tunes it to the best of their ability to your needs. The catch is that the MS (and most all other aftermarket ECU's) aren't and can't be fitted with OBD-compliant signalling so that it could be emissions tested. That's not the tuner's problem and, again, you might have to sign a waiver about the road-use of your vehicle.

Since I came to Georgia from Michigan (where there is no emissions testing), I've had to de-tune my car every year in order to pass the GA OBD testing. After that ordeal, I'd "ride dirty" for the rest of the year. Since I built my own engine tuned my own MS, no documents were signed and I'm solely responsible for my anti-social behavior.

All of that to say this; You can DIY and accept all "blame" if you get busted, or drive with the stock ECU, not put anyone else in jeopardy and make everyone happy (except you "Need For Speed")

About 15 years ago when we first started getting the MS1 to work on miata's. We would wire them in parallel with stock ECU's. Some of us ran switches so we could switch back and forth from the MS controlling fuel and spark to the stock ECU controlling them. It was not a fun time at all. I do not recommend going that route.

I have "no idea" what this thread is "about" anymore but "I kinda" like the "use" of quotation "marks".

Sign the paper and let your builder legally off the hook. What you do with the car afterwards is your business. Hell, maybe you WILL decide to trailer it. He doesn’t need to know your whole life plan.

You can’t expect the guy to assume your janky switched harness is road legal. It probably isn’t, nor would highway patrol think so if your regulations are that strict.

Trip down to memory lane...circa 2005.

MS1 in parallel with the stock ECU on my 2002. Select box above the stock ECU to select injectors (4 switches, top of box, can't be seen) and ignition (two switches, side, can be seen) between stock ECU and MS1.

I think that's what the op is asking for.

https://cimg8.ibsrv.net/gimg/www.mia...32b85aa725.jpg

Between options, 1. Sign the paper and 2. Do what Reverant did... Yes sir, off-road use only, I just haven't gotten around to taking that tag off yet.

Whats that? 1MP? 2MP?
cutting edge tech back then!