2005 Mazdaspeed Miata Project - Help

Well, I'm back. I have almost gotten my son's 2006 MS6 finished, so I am going to turn my attention to my 2005 MS Miata project. I do have some questions, but I'll first bore you with a little of the history of the car (at least since I've owned it).

I had originally bought a first gen miata for a project car and went to buy something from my part-out guy. While I was there, I saw he had a hella-nice 2005 Mazdaspeed Miata. We worked out a deal where he hauled off my project car and I got the speed for a little additional money. It is a sweet little car and has a pretty good bit of power for the size. It is fun to drive (when it runs).

I drove it for a bit, as did my son (who actually had a wreck and I had to get the whole thing re-painted, - story for another time). Anyway, I drove it several hundred (or thousand) miles, but never get the emissions test so I can register it. The car always threw some code. I tried a new gas cap (which it said at one point), new plugs and coils, etc. but it never cleared up.

One night, while driving it home, it cut off on me -- just died in the middle of third gear. I coasted to a parking lot and tried to start it again. I did the thing where you bypass a solenoid or switch or something to reset the fuel pump, but that wasn't the problem. I was able to get the car to start, but it would only run if I kept feathering the throttle. After a little time in this session of trying to start the car, the center hump (behind the gear shift) got really hot and started smoking (probably steaming, more accurately, because the carpets had gotten wet from rain the night before). So, I had the car towed home.

After scratching my head a bit, I decided that the catalytic converter must be clogged, and that is why the car died. I'm not sure how I reached that conclusion, but I did. I ordered a new turbo-back exhaust (complete with cat) and prepared to install it. In the meantime, I went back to my part-out guy, and he happened to have another speed miata that he was parting out. It had been upgraded with a JS Turbo (I don't know much about turbos but this one is so much bigger than the one currently on the car - it is 3" diameter where the intake attaches), intercooler, complete exhaust, etc. I had only gone to get some new seats and door cards, which I also got, but I came home with all of that stuff - and a mega-squirt ECU.

I returned the exhaust I had ordered, and am now preparing to start the job of replacing the parts. (By the way, when I removed the exhaust from the car, it does run. I think maybe I was right about the catalytic converter being clogged.) Now that I have given you that incredibly boring and long ass introduction, I need to say that I am really writing to ask for help with the following challenges;

• Intake & Airflow Sensor - I know I will need to get some sort of air intake system to go on the new turbo, but how do I manage the air flow sensor that was on the original intake? Do I really need an airflow sensor? Can I make my own intake and just have a threaded bung for the airflow sensor?

• Tune - Can I get a tune on this thing such that it can pass state emissions? I think I'd like to run with the mega squirt, but do so, I think you attach the megasquirt to the same connections that you would use to connect the computer at the emissions control inspection station.

I am sure I will run into more questions as I go, but these two are the stumbling blocks preventing me from actually getting started. That, and the fact that I am going to have some parts powder coated before installing them. Actually, it is a high temperature coating that uses a similar process to powder coating.

Anyway, thank you for any help you can give me with my questions, and I would appreciate any other tips, tricks, or ideas you can throw my way.

Thanks.

 

Which Megasquirt system did you get? You won't need a mass air flow sensor with the MS system so you can just delete that and tune based off MAP only. I can help you out with a lot of stuff on the Miata. Shoot me a PM with your number and I'll give you a call when I get a chance

 

I will do. Since I am a ways off from actually turning wrenches on the thing, it might be a few days. I'm kind of in the research phase at this point. Thanks for being willing to help.


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Question 1.

The MAF sensor will be deleted. You will take the two wires at the MAF sensor and wire them to a GM Fast Response IAT sensor. This sensor has calibrations pre stored in Tuner Studio so it's easy to swap to it.

You will have to get custom intercooler piping made or buy a premade kit. I recommend contacting Lars at MKTurbo.com. As for the bung location I have mine located right after the intercooler before the throttle body so it's getting post cooling readings.

As far as emissions goes you can't pass it with Megasquirt. You won't have OBD2 readiness monitors using that ECU so you're gonna have to try and trick it somehow. Check out www.miataturbo.net as there are probably people who can help you with your specific issues regarding emissions and Megasquirt.

If you have any other questions feel free to ask me. I can also send you a copy of my tune file to give you an idea of what I'm running.

Some things of note that you should upgrade

Oil pump. I run a Boundary Engineering billet pump. The factory pumps tend to crack

Crankshaft balancer. I use a ATI Super Damper.

Differential mounts and reinforcement plates. They sell weld in reinforcement plates for the diff housing. Worth the money

Upgraded injectors preferably 640cc or higher

Audi R8 ignition coils are a good upgrade and depending on the MS ECU you have will determine if you can run them. If not then GM LS coils are a better option if you're limited by ECU design.

Definitely upgrade the brakes to a solid Wilwood setup. I got mine from Flyin Miata and the brakes make a big difference especially on the track.

 

This site is awesome! Y'all are so great in being willing to help me out, I hope someday I can return the favor. So in answer to a couple of posts above, I'll have to check out the megasquirt (I think I stored it either in the trunk or the glove box of the car) and get back to y'all. Since I am an old geezer and don't know much about what I guess people call "tuner cars, this is all new to me. In fact, I've never really messed with the OEM tune on a car until my son go t his Mazdasepped 3, and then the 6, and now the Miata. I have a lot to learn, but it is kind of cool.

The intercooler I have does have piping, and there may already be a bung on it for the sensor. I am not 100% (again - all sort of new to me, here). I will add a couple of photos of the parts I have and maybe you can help me understand how best to install all of this mess. I'm good at turning wrenches, okay at diagnosing, but don't know squat about turbos and ECUs.

Thanks as always.

 

I'm not sure what the point of the hose is that's coming off the intercooler piping. You can probably just thread an IAT sensor in there.

Is the BOV after the intercooler or before it with the way that setup is routed?

As for Megasquirt systems they are listed as MS1, MS2, or MS3Pro. I opted to get the Pro for my car since it had the most options available for it and the most versatile of features. The 1 is the most basic with no expansion board etc.

I would recommend getting a different intercooler than the one you have there. Especially if it is a generic eBay core. I noticed a big difference going from an ebay core to the Flying Miata IC but a Treadstone IC would be equally good.