Electronic Boost control from unused wire in loom
 

I just got my EBC in the other day from DIYautotune. I want to wire it in but what I see most people do is connect P6T to boost control in and boost control out to one of the DB15 pins. I want to avoid using P6T if I can so I can run sequential injection later on.

I really don't want to run a wire into the DB connection in front of the MS so I was wondering if anyone has used something from the stock wiring harness to run boost control. That way the install looks nice and clean. I have a 90 1.6L car without AC or PS, has anyone tried to wire their EBC in like this?

Yes you can run it through any unused wire in the engine bay that goes back to the ecu. You would just need to hook up the corresponding wire at the ecu to whatever output you set EBC to. I don't know 1.6 cars off the top of my head so I can't really recommend what wire to use. Maybe something in AFM connector.

Evap purge solenoid has 12v and a switched ground wire at the ECU.

That would be great if I can use one of the AFM wires for this. It's close enough that I could easily hide the wires and mount the EBC in a coolish location. If I was more confident in my ability to read a schematic I would do the leg work on finding an unused wire but, my electrical ability falls short of my mechanical...by a good margin. :facepalm:

Do you know which wires those would be at the MS connection by chance? That would be good to use since I don't have it in the car anymore.

So I think I found it. It's a yellow wire labeled 2x on this diagram.
https://www.miataturbo.net/attachmen...ine=1455310216

So in the Megasquirt itself how do I identify where this wire is pinned?

Here is the .PDF in case you can't see the hosted jpeg. http://www.miata.net/garage/ECU%20Pi...90-93%20MT.pdf

What MS do you have?

DIYPNP

So factory ECU connectors right?

Right

It's wired as 4X on the jumper board inside the DIYPNP for a 1.6 miata.

So will the wiring look something like this...

Inside Megasquirt
4X to Boost Control Out
IAC/PT6/PA0 to Boost Control In

Inside Car
Polarity isn't important with the MAC valve so..
Yellow wire from purge valve to one wire on the MAC valve
Other wire on MAC valve to any ground


Is this correct or is my understanding wrong?

No, the megasquirt is a switching ground in this application. The other side of the valve must be wired to 12V. That's why the purge valve is cool, it is an ECU switched ground wire and a 12V wire off the main red/white engine feed.

Or you could wire it to ground, just won't do much at all.

Oh, interesting.

So both the wires going into the purge valve can be used here by just hooking them right up to the EBC (red/white and yellow wires)? I am assuming that the wiring inside MS was correct in my post though?

Yep, that's it.

You're my hero. :likecat:

I always wire it through the AFM/MAF connector on my MS setups since 9:10 people put the EBC solenoid near the wastegate.

power can be tapped at the diagnostics box or the blue power connector.

Not that I've ever heard of anyone having a problem before, but the DIYauto valve is only rated at 122f/50c.

Since you should always source the wastegate source after the intercooler, as close to the throttle body as possible it just made sense for me to mount it off over there, near the throttle body on the cold side.

I also put it in the AFM connector.

With ebc the location of the wastegate source doesn't matter.

What connection in MS do you make for the AFM to run it? I forgot about the blue power plug. I could just put a spade connector on it and wouldn't have to chop into my harness that way. I only use the blue connector to check timing anyway and the EBC can be open for that.

I used the maf wire i believe

I disagree, why would you purposefully make EBC have to work harder? When I'm in boost I only see maybe 5-10% difference between the start of a pull and the end. If I was sourcing on the hotside, that range would be much larger.

Plus, I just turn mine off if I want low boost. It's pretty important it's on the coldside for that.

Because you aren't actually making EBC work harder.

EBC is calculating duty cycle based off of your MAP signal, which comes from the intake manifold, as cold side as it gets. It doesn't matter how much boost the wastegate is seeing because EBC is controlling that.

Yes, you are making EBC work harder.

Instead of just having to increase/decease boost as necessary to match engine requirements, you are now having EBC deal with pressure drop of the engine and intercooler both.

It can and will do it, but it's not right.

Nope. Once you have tuned it (initial value or bias table) then the pressure drop of your intake piping is already taken into account.

All EBC does is control what the wastegate sees. So EBC can make it see whatever it wants, no matter what the boost source is.

So I don't see a maf pin on my board, but I do see a MAP pin. Do you know what wire that corresponds with on the AFM plug?

I don't know shit about DIYPNPs

Well hawt damn, back on the grind.

So according to this diagram the WOT switch on the 90-93 is 2L. Does this 2L also correspond with the 2L pin on the expansion board?

https://www.miataturbo.net/attachmen...ine=1455323579

No, any time you see a 2, you need to make it a 4.

Unless I'm mistaken, the pins numbered #2 and #3 are for other 1.8 miata. No plug on your 1.6 harness will fit anywhere else, the ECU plugs should be in #1 and #4 spots...

I see, so 4L should be the pin I use with Megasquirt? I guess that is why you said 4x earlier. Just making sure it wasn't a coincidence.

Nevermind, just pulled the MS apart and I am using 4L for my vTPS.

Yep, see how all the jumpers are to 1 or 4 on this 1.6 assembly chart? DIY broke the page, so this is cache and looks funny. If you compare this to your picture and line up other things like spark outs and injectors it will all make sense.

https://webcache.googleusercontent.c...&ct=clnk&gl=us

Thanks, this does make it much easier to track each wire, but some of the wires are not mentioned on the DIY assembly chart. But my harness still has them, do these unmentioned wires still correspond in the same alphanumeric fashion?

Thanks for all your help so far. I'll be putting a video together of this process and would really like to get it right so I don't put out any false information when I start to film it.

Yep, that's how you find unused wires, or at least a starting point of it all.

Awesome, thanks for all the help. I'll install it all tomorrow, looking forward to seeing how it turns out.

So now that I have everything wired in how can I now find the wires in the car?
https://www.miataturbo.net/attachmen...ine=1455331596

So when I look at this wiring diagram under CONN#2 I see that the K wire goes to the AFM but it also goes to the Throttle sensor. Will this be a problem when I install the EBC? Assuming that the LT GRN-RED wire is the correct one.


https://www.miataturbo.net/attachmen...ine=1455331545

That used to be a 5v reference signal for the tps and air meter. You'll want that for a vtps mod.

Then I don't understand how people are using the AFM wiring with a VTPS. With an IAT installed you don't have options.

The 1.6 has a few pins that go back to the ECU that you could use for the boost solenoid.

AFM Connector Pin
1 4P
2 4O
3 SG
4 4K
5 GND
6 GND
7 Fuel pump trigger

You can double check with a multimeter.

Could also use the purge solenoid wiring on 4X or the power steering switch wire on 1P.

While this is true, one of the things I like about EBC is that it's easy to flip it to a low boost setting by installing a switch to cut power to the solenoid, and at that point you'll want the clean boost signal source.

As for wiring, I hate hacking up the factory harness so I tend to use unused pins and run new wires for things like this.

--Ian

How would you check this with a multimeter? Would I enable the switch in MS and check for 12v at the wire or is there another way?


I've currently got 4K pinned for my boost control source but the wiring diagram I linked shows that it's also used for the TPS. I also have my GM air temp sensor run through my AFM harness so those pins are also used.

put it inside your cold air box.


if you dont have one, youre dumb.

Brain, what wire do you use for EBC in the AFM?

I use P for AIT, O for fuel pump, so that really leaves one...

So how do you get K to work without interfering with the TPS signal?

why would that interfere? do you have an automatic?

They are connected at a terminal, according to the schematic I have.

I don't have an automatic but I do have a VTPS hooked up there that I believe is using the 5v reference wire.

look at the wiring diagram again. you have 5vref wired to 2N. you dont have an automatic, so it doesnt matter about 4K, that wire doesnt go back over to the throttle on your car.

Does the red line not affect the TPS signal from the AFM connector and 2K on the ECU pin?

https://www.miataturbo.net/attachmen...ine=1455378396

Quality penmanship fo sho.

I cut my image off too early. :(

Thanks for the help.

:bigtu:

:bowrofl:

So I got everything in the car and moving. Setting up a decent target boost map was somewhat challenging. Open-loop stuff to start and I may jump into closed-loop PID settings later on.

Any input on torque curve? Load looks pretty linear and transmission safe to me. I may try to push this little 1.6L a bit harder in the future, but 12lbs pulls pretty good. Enough to make 1st gear somewhat useless.

https://www.miataturbo.net/attachmen...ine=1455467492