So I'v started working on a '94 miata. The driving club at my school has been "working" on it for the past seven years, and in that time they have rebuilt the engine and turbo'd it with a begi kit as far as engine mods go. It was sort of their drunken project, and the people who first started it have now graduated so the current members of the club are in the dark about a lot of the things with the car. I'm sure you guys can help me out in some way.

So the first problem has to do with the EGR and AIR valve. We have EGR, but don't have AIR. (I actually don't really know what AIR cause google keeps thinking i just mean air . I'm guessing its the exhaust feed for the EGR but thats a guess.) Anyway, we wanted to delete the AIR completely, with a fabricated piece that would seal off the port where it would fit on. We would leave the EGR on but it would not be in use. It was serve the same purpose as a fabricated seal, like on the AIR, but we do not want to pay for it. Someone at NAPA said this would be ok but I'd like to hear from some turbo miata people. Would the car run fine without AIR and EGR? We do not care about passing emissions tests.

Second, I noticed that the two hose nozzles at the bottom of the radiator have no hoses going out of them. That's pretty much all we know about the problem. We have no parts around the shop that look like they are coolant related. If anyone can help me get a foot in the right direction to the solution here I'd appreciate it.

The last problem is ECU stuff. As of right now, we have the stock ECU hooked up and (we think) everything we need is wired up (the wiring harness was not cataloged at all and we mostly guessed which plugs go where). We do not want to pay for a plug and play, so we are going to use some stand by ECU's for fuel management, and just run wastegate pressure as the boost controller. What would we need to get a standalone FMU running? Any extra sensors, hookups to stock ECU? Also what is a quality FMU that we can get for cheap?

I'd like to hear what people think about he whole project as well. This motor has not run in seven years, so I'm not sure of the whole thing myself. Any advice would be appreciated!

 

This sounds like a scary endevor. College mechanics had free reign for a year? I'd be scared.

BEGI's adjustable fuel pressure regulator requires a wideband oxygen sensor to be properly adjust, as well as a fuel pressure gauge, which I'm assuming the shop has. If you don't have a wideband, one can be purchased for a few bucks under $200. Either AEM or Innovative.

The regulator itself costs $229.
2025 FPR For Aftermarket Turbo and Supercharger. BEGI Bell Engineering / Cartech

Now, a standalone ECU (the MegaSquirt) kit starts at $207.
MegaSquirt-I Programmable EFI System PCB3.0 - Kit w/ BLACK CASE DIYAutoTune.com

A few other parts are needed, such as a intake air temperature sensor, will cost less than the $22 difference. See why we recommend MS so much?

Find someone in the shop that knows how to solder (a skill you should learn anyways), and you've got yourself a standalone ECU for less than the fuel regulator.

Find some bigger injectors either here or in a junk yard ($40-$80) and you'll be running much better than any fuel regulator.

As for the EGR, most people fabricate or purchase a block off plate if it's not required for emissions testing, then just thread a cap onto the port on the exhaust.

Trackspeed Engineering

Good luck with your project.

 

Ok so the megasquirt will go in place of the stock ECU? Sorry I'm still learning about electric stuff. Iv heard the stock injectors for the 1.8 will be ok for turbo applications, especially since we will be running around 7 psi.

 

They're fine for auxiliary fuel pressure regulators (AFPR), not for megasquirt.

AFPRs increase fuel pressure through stock or slightly larger injectors to fake an increase in fuel flow. This often necessitates an upgraded fuel pump, since your pump will now need to flow up to 100+psi, rather than the stock 43psi.

MS effects the electrical signal going to the injectors, varying their spray from zero to 100% duty cycle. Because of this, instead of the stock ~235cc/min injectors, we require 400+cc/min injectors, sometimes going as high as 1000. For 7psi out of a 1.8, you'd probably want some RX7 or RX8 injectors, which flow in the 440-460 range, depending on the year.

 

Wait...seven years and this thing still isn't running...did I read that right?

(@ those who came before you)


Now you on the other hand. . .are off to a good start with the questions you're asking.

 

Thanks, hopefully everything the other kids have done up until this point is ok. I'll research the megasquirt system some more and we will be buying the egr and air covers soon. Any suggestions on the coolant problem?

 

You say 'problem.' Do you know there is an issue, or are you simply trying to figure out the purpose for the extra taps on the radiator?

Extra taps in the bottom is strange. Not sure why they would do that.

 

Extra fittings in the bottom of the radiator are usually for the transmission cooler on automatic transmission vehicles. If you have a manual transmission then you can ignore the fittings since you won't have anything to connect to them.

 

Well there are no hoses at the bottom of the radiator at all, the only hose going out of the radiator is on top, and is about 1.5 inch in diameter, going to the back of the block. The hose nozzles on the bottom of the radiator look to be a half inch in diameter, and they are not blocked off leading me to believe they were taken off and not put back on.

 

Pictures would make answering these questions much easier.

--Ian

 

The fittings are for the auto trans cooler. This is a seperate core inside the radiator. They can be left open without issue.

 

This. And the auto radiator does have a bit of extra cooling capacity when compared to a manual radiator, so it's a good thing.

 

Ok great, so coolant problem is fixed! Im going to look at the megasquirt system and see what that entails, and the egr valve covers are on their way. Thanks everyone! If i have any more questions I'll post up