Long time stalker, first time poster. Be easy on me.

I'm currently finishing up my installation of a 2004 VVT motor into my 1994 NA. I've completed all the nuts and bolts and have begun the more challenging aspect of the swap--the electrical system.

NOTE: I'm aware that under my current setup I will not be able to control VVT out of the box. I have plans for this in the future. As of now, my main goal is to get the car running.

1.) Ignition Wiring: I'll be integrating the 2004 coil and plugs into my 1994 harness. After much research, I've come to the following conclusions (Please confirm).
(1994 Harness) ------------------------> (2004 Ignition)
Black (Ground) to Black (Ground)
Blue (12v) to Black/White (12v)??
Black/White (Tach Driver)
Brown (Trigger) to Black/Yellow (Trigger)??

Wiring Diagrams Used:

1994 Page 8 http://www.madracki.com/miata/images/wiring/94sys.pdf

2004: Page 11 http://www.boostedmiata.com/pdfs/MSM_wiring%20all.pdf

1a.) What is the best method to wire in the Tach Driver, seeing that the 2004 Coils don't require it? I'll be using the stock ECU.

2.) Wiring the gauge temperature sensor. I know, based on Joe Perez post, that the NA gauge temp sensor is a single wire on the back of the block. However, the VVT motor doesn't have this port. Is it possible to tap the sensor used for the ECU to operate the gauges as well (I have swapped over the NA sensor)? Or have some people tapped this housing and used the stock NA sensor temp gauge sensor? CLOSED: Thank you Richyvrlimited!

Thanks in advance,

Flying Goose

 

It does have the port, look harder, it's filled in with a small grub screw.

 

Ah, thank you. I didn't see one and figured since the NB used the rear housing sensor Mazda wouldn't of installed one. Thank you!

Also, I realized that my proposed wiring was a little difficult to follow in the above format so I put together a quick JPEG.

 

the little plug is on the opposite side of the head as the na motor was. Just gotta get a good light and look back by the heater hoses.

Good luck with the wiring. I tried this with my vvt set up and couldnt get the 3 wire 01-05 coils to fire. I gave up and am going to go with a toyota cop's

 

Any reason why you are wanting to run the 01 coils instead of the 94 coils?

Without an aftermarket ECU I do not think you can get the tach to work.

 

I did it for three reasons:

1. The plug wires from the 94 Coils didn't fit in the VVT head
2. Didn't want to deal with mounting the 94 coils.
3. A individual from a major vendor from Miata.net said it was easy and how everyone runs them

Sounds like more homework was required on my part ::

 

1. You should be able to make the coil wires fit. I know the coil wires from my friends 99 fit, I just had to trim down the sides of them a little with a razor blade.

2. You can pull each of the 2 actual coils off the bracket they are on and mount them to other places with zip ties for the time being so that you can use them.

3. Well if you are not using the stock ECU it is easy to get a tach signal. All major standalone ECU's can do it. Most people who do the VVT swap are not using the stock 94 ECU.

 

Sounds like I might have to go back and use the 1994 coils, which I don't mind.

Question, does the original wiring diagram work? Knowing that the tach driver wouldn't be functioning?

 

From briefly looking at how you want to do the wiring it should work fine.

In my friends 99 we really did just ziptie his stock coils to things and he has been driving around for a few months now and has had no problems.

 

Might have to happen this way.

Has anyone ever tapped the CAS signal, created a tach driver, and integrated it with a stock ECU. Not saying I'm going to do this, if possible, but I was curious.

Looks like I'm getting the trusty zip ties out

 

I am not sure if anyone has built an independent Tach Driver. Seems like more work then just building a MS and using that or using cops.

 

After extending the CAS sensor, she fired right up! Thanks for all your help. Just need to button her up and she'll be ready to go.

One question though, at start up she is reading close to 90PSI. I've read that many Miata owners experience this when the oil is cold but wanted to confirm because my only experience is driving one that had 60PSI in each cylinder and a leak down of 25%! So driving one with a healthy motor is new to me

 

Did you put on the oil pressure sender from your old 94 on the new VVT motor? I think I see close to 90psi when I start the car. I will look and see when I leave work today.

 

I peg my oil pressure guage at cold and then driving warm it goes to about 60 psi and at idle about 45 psi. So that would seem normal to me.

 

Did you ever get the tach working? I am about to do this myself and am wondering about the tach......