CMyles

​1990 Mazda Miata
No AC, has stock TPS, will have GM IAT

Hey everybody,

So I ended up purchasing a parts car that had a bunch of turbo bits, and some goodies that made it worth it to buy it and part it out.
Surprisingly enough, the car had a Megasquirt DIYPNP sitting in the trunk when i picked it up, but was still running on stock ecu.. I later found out the previous owner to who I purchased it from had bought it, and the owner after had never bothered to install it..

So I pulled the ecu apart and started checking wiring, and it seemed to match up to a 90-93 Miata, but with some variation.
I was wondering if somebody could give me some insight on what these differences in wiring may mean. I have done my research and sorted out a few, would just like to get a second opinion.

I've modified the table to show what connections my car has.



Just wondering if anybody can help me out with this!
Really excited to get my car running on this, but want to verify everything before I install it and turn the key.

Picture of my chicken scratch

*** ANYTHING HIGHLIGHTED MEANS THE CONNECTION MATCHES ***
**** STRIKE OUT INDICATES SOMETHING THAT IS DIFFERENT FROM GUIDE ****





So, as far as I know..
ECU Is set up for a
Variable TPS
Wideband O2 Sensor Wired to DB15 pin 15
Boost Control Solenoid
Possibly Launch Control?

mmmjesse

upload some pics of it also. picture can be worth a 1000 words.

CMyles

Hey thanks for replying so quickly to this.
I will upload the pictures I have so far, but I will get some more detailed images tonight.
I know these are terrible but they will have to do for now!

CMyles

Here are some better pictures:

CMyles

Nobody has any insight that may help me on this one?

Matt Cramer

Looks like he's running it with a variable TPS and a wideband.

CMyles

So only things I am questioning are the following:


A/C (Car does not have A/C)
1Q – INPUT(IN)

Boost Control Connections:
DB15-(13) – BOOST CTRL (OUT)
PT7 – BOOST CTRL (IN)
PAO-RELAY 1(OUT)

Wideband Connections:
DB15-(15) – O2

Unknown Inputs?
1U – INPUT 2(IN)
PE1 – INPUT 2(OUT)


Have no idea with the 1U and PE1 pin are for. Has anybody used these? PE1 is for table switching, and 1U I can't seem to find any info on.

Braineack

iTrader: (62)

I built that (long ago)

I would change just the a/c in/out so it goes into the ECU, and load the latest firmware (would need r14 installed).

otherwise it's good to rock and roll once you remove ST_SIGN since it's using the HIGH SIDE DRIVER circuit for fuel pump.



It should be 1V and it's for the clutch switch for launch control.

CMyles

You built this specific ECU?
That's pretty nifty.

Would you guys recommend finding a VTPS and running the boost control option?

Also, what is the 1U wiring circuit for?

Braineack

iTrader: (62)

Yes, I built that actual unit.

Yes and Yes. If you don't have a vTPS now, you MUST unplug the stock TPS else the car wont start.

I made a mistake apparently and it should be on 1V, not 1U -- it's for the clutch switch.

CMyles

Thanks for the info, it is much appreciated!
Am I able to drive the car with the TPS unplugged?

Braineack

iTrader: (62)

you SHOULD put jump 4L to GROUND via a 1K resistor. that forces the TPS signal to 0%.

you'll use MAPdot enrichments, so yes, you can drive around without a TPS. The MS can't do anything with the stock tps anyway.

CMyles

What happens if I do nothing about the A/C Circuit and leave it wired as it?

mmmjesse

it should not do anything. you will just make sure that the AC idle up is turned off.

Braineack

iTrader: (62)

The A/c will work as wired, but the MS is not in the loop. They've added a/c controls to the firmware since that unit was built, so you can input the a/c switch into the MS and then the MS can turn on the a/c compressor. Then there's idle up code that you can tune that opens the idle valve and target rpm speed so it's a seamless activation. Otherwise CL idle is reactive and the sudden increase in load and drop in voltage can cause the idle code to dip and become unstable momentarily -- however the improved idle code like the adaptive timing and and voltage pwm% compensation might actually be perfectly sufficient without a/c idle up.

CMyles

In my cars situation, it does not have AC, does this still need to be done?

Also for updating firmware, is it as easy as updating it through tunerstudio, or do I have to add in the boot jumper, use megasquirt software to update the firmware etc.
I tried following some tutorials, but I didn't have enough time to figure everything out. Seemed like I needed a megasquirt based software to do so, not tuner studio.