If you cut the firm-ish line off the OEM plastic fitting, it's barbed underneath. I slip 5/16" fuel hose over that with a hose clamp and I've never had any issues with it.

I have both 2004 fuel rail and 1999 fuel rail and I cant figure out what you mean by retaining the fuel injector fittings from the 2001-05 fuel rail. The fittings look the same to me.


Also, doesn't the VVT motor FPR regulate fuel to be @60psi vs 43psi for the 90-93? I'm using 2004 injectors with the 90 fpr, would the decrease on pressure affect the injectors? I am running a ms3 so fuel tuning will be done, obviously. Has anyone added an adjustable FPR? What about this one? http://www.miatacage.com/adjustable-...egulator-90-97

Here is a picture for reference. 2004 fuel rail on top, 1999 with 90 for on bottom. I don't know which fitting from 2001-05 "that needs to be kept" you are taking about. I'm confused
https://www.miataturbo.net/attachmen...ine=1451866933

What color wire are you guys tapping of the injector harness for the vvt solenoid? Is there a way I can find out which one is the 12v without having the car on?
Could I use a 12v 2amp source from my megasquirt instead?

I'm referring to the plastic adapter attached to the fuel line that clips onto the fuel rail. You can use an aftermarket adapter too, but the 01-05 rails have a nice 90deg fitting that helps clear the alternator. The decrease in fuel pressure is not an issue, but if you want, you can run an aftermarket adapter.

I tap the 12v wire on the CAS plug for VVT power. On the injector harness it should be one the white/red wires that you can grab power from.

does the nb IAC valve have polarity?

Please read the original post in its entirety before asking questions.

Thanks Savington for all the info. I kept the original vvt engine harness and used Deutsch connectors on both ends. I think it will end up working pretty well. Looks stockish
https://www.miataturbo.net/attachmen...ine=1452204685


https://www.miataturbo.net/attachmen...ine=1452204685


https://www.miataturbo.net/attachmen...ine=1452204685

Awesome info in this thread; it helped me swap a VVT into my to my NB1. I got it started with the stock ECU (small miracle), and I have my MS3 Basic waiting to go in, but I'm not sure which wire to tap on the injector harness for the 12v VVT actuator. I'm using the 2003 injector harness, and I think it's the white wire with the blue stripe. If anyone can tell me for sure before I spice into it, I'd appreciate it!

Thank you!

Blue/white is +12v on the injector harness, it's black/white on the spark harness. I used the spark harness, but I am sure either would work.

Logically, there is one wire that provides +12v to all four of your injectors. It will be the same color going to all four injectors, so look at a couple of your injector connectors, figure out which wire is shared among them. That's the +12v. :)

This is going to help me too.. Thanks

Im in the process of doing a 01 vvt w/90k in my 94.. I already droped in the motor this past weekend.. I swap to the 94 na thtottle body to use my org tb plug etc.. Is that ok?
Im geting a 99-00 nb fr from my buddy and maybe fpr too..(ps can someone post me pic on how to route the fuel lines, what goes where to where) i have an idea but dont want to do it twice..
I have a vvtuner here at home, i dont have any instructions on where to wire thing up..

I just read this entire thread and seems like im on the right track 👍👍

I'm pretty sure the hardlines are the same in both NA6 and NA8 chassis. This is accurate for NA6 for sure.

Feed: rear hard line to fuel rail quick-disconnect fitting
Return: FPR to front hard line

5/16" fuel line

For you guys using MS3, do you enable alternator control in tunerstudio when using the 94-97 alternator? Do I set it to closed loop field control?

The ECU doesn't control the 94-97 alternator. It has on-board control and doesn't need any input from the ECU. Just plug the 1.6L alternator harness into the 94-97 alternator and don't touch any ECU settings.

That's what I did, stupid question. Sorry

Does anybody know if the threads are different on the vvt block where the vvt oil line hooks up? Can you say bolt that line to a 94-97 block?

I knew the answer at one point but I can't remember anymore. I think the VVT blocks are BSPP and all the older ones are BSPT. That banjo fitting shouldn't work with tapered threads.

yea I'm pretty sure that oil pressure switch uses tapered threads. without VVT it would thread straight into the block. I think the sensor will thread into the straight threads but wouldn't seal.

Seems like it would make sense that the VVT blocks have straight threads there for the banjo but I don't know for sure. Also not sure if it makes a non VVT block a no go for adding VVT. maybe straight male thread could be forced in or a light re-tap before shipping it off to the machine shop for bore hone and clean would work.