Parallel OBD 2 MS3 PRO, what problems will I need to solve to pass emissions?
 

I'm installing a MS3 PRO into my 99' miata, with 100% of the factory emissions equipment installed, every piece, catalytic converter, MAF Sensor, egr, evap, etc. Factory ECU will see every factory sensor, MS3 PRO will be running fuel/spark/etc. This is for emissions testing/compliance. I'm working on wiring right now.

What potential problems will I have to solve?

I ready through some of y8s comments from when he ran parallel. And other's who ran parallel as well. I see most agree just swap stuff once a year for testing.

It seems the biggest potential CEL will be for short term fuel trims. Basically stock ECU sees the motor running say 14.6 AFR, so it says less fuel because running rich, but MS3 does nothing, so ECU says LESS FUEL STILL, and this happens till short term fuel trims are maxed, then CEL.

Other than that, if EVERY sensor is installed and working correctly, it seems to me this is the only potential CEL I would get, right? If so, I could potentially swap in stock injectors for emissions testing and let the factory ECU run them, have dual plugs for the factory injectors and ID 1Ks and swapping injectors is easy enough. 10 minute swap, drive around, pass emissions?

Any other ideas? I can't think of an easy way to make it pass this one any other way since MS3 PRO and factory ECU don't talk to each other. Maybe if EGO correction was always running the factory ecu would constantly target 14.7, 14.68, 14.69, 14.7, 14.71, 14.72, 14.71, etc, and the factory ecu would see this and be happy, but I don't know that.

Also leave the factory plugs for the 99' coil pack, so it would be swap injectors and swap to factory coil pack, so 99' ecu has full control of fuel/spark. Then it should definitely pass emissions. I would have to buy a 99' coilpack but no big deal. Doing it this way should make "swapping" to pass emissions a easy/quick process.

y8s decided it was easier to swap injectors, reinstall MAF, and wire wastegate open a week every 2 years.

I know you're not y8s but.... Did he pass emissions with the MS/Adaptronic running spark? I'm trying to go with what works on this and get the car back together. I think I'm just going to keep the Coil pack and Injector plugs in their spots so if I needed, both are ready to be swapped.

i believe he passed with MS3 parallel.

unsure about adpatronic.

Has anyone tried using something like a jimstim to fool the factory ecu into thinking it is controlling things? Just feed it a constant maf, Afr, cas signal?

Edit: didn't know how illegal this was, ignore my post if necessary :)

This is what I do.

I originally had a MS1 in parallel and I can pretty much guarantee that the ECU will not be happy enough to pass readiness codes if you are in parallel. Don't bother.

Yeap 99% sure that's what I'm going to do, just swap parts as needed when the time comes. At this point just going to design it so it's easy to do so, leaving the injector plugs, coil pack plugs, etc all in place.

I played with parallel for about a year. I am not convinced it can't be done, but I know it can't be done by me with my current level of dedication and focus. I'd much rather spend my mental energy elsewhere and so I converted back to stand alone.

I think his biggest issue was that he had no rear o2 sensor and/or cat, so he built an emulator.

I remember he passed emissions but soon just went full standalone after that. IIRC he passed again in two year without any issues just swapping injectors and reinstalling the MAF and driving "n/a" for a week.

Ok possibly dumb question....

What sensors should I share from the factory ECU to the MS3 PRO?

Cam, Crank, TPS for sure. I will run GM CLT, AIT of course, so don't need to share those.

Anything else? Can I share the knock sensor?

If you're going to go through all that work. Stick an arduino in the car with the full stock setup and have it sniff the obdII serial data both ways when connected to the damn emissions computer and then program the damn thing to output that when queried and wire it to the damn OBDII port. This is just as illegal as removing a cat, dont do it.

Purely hypothetical here (I have a 1990) but if all the ecu uses is AFR to determine readiness then all you need to feed it is the correct voltage signal on the stock narrowband wire.

not even close. the nb uses a ton of sensors and systems all of which have to play together just right. it's finicky

Look at it this way.
The emissions computer is a member of the Gestapo, when he gets plugged into your cars computer his demands, papers please. And your jewish sympathizer car meekly replies with its make, model, vin number, and all its emissions readyness states. What you're proposing is making a set of cloned parents with fake names, founding a fake city, and opening your own german authorized printing facility in order to make a set of papers that pass muster, where I'm suggesting that you merely make a set of forged documents.

Lol :) sigworthy

I passed with the Adaptronic. Because I am the fucking man.

Check it: https://www.miataturbo.net/adaptroni...82/#post476173

There's all your ingredients, now you just have to be a chef.

:rofl::rofl::rofl::rofl: