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-   -   The Definitive "VVT swap into 90-97 chassis" Megathread. (https://www.miataturbo.net/engine-performance-56/definitive-vvt-swap-into-90-97-chassis-megathread-80469/)

emilio700 03-03-2015 01:12 PM


Originally Posted by wkndracr (Post 1211688)
For those running a stock VVT motor, what does your spark table look like? I swapped back to an OEM airbox the other day and today I noticed what sounded like pinging while cruising on the highway at 4k rpms if I gave it a bit of gas, although it's hard to tell with all the wind noise. I've been running the same tune for almost a year, and haven't blown it up yet, including a few autocrosses and a track day, let alone about 20k street miles, so I don't think my tune is that off, but I'd like other opinions. Here is my current spark table. I don't remember exactly where I got it from, but it was snagged from a thread somewhere on this forum.

Yikes. What octane/state?
Without seeing your VVT table, I'd guess you're about 5° too much advance everywhere. Have you verified base timing? Restricted intake would not likely lower det threshold unless you're getting a ton of heat soak. Plastic intake pipes will do that.

Anyway, this is a bit of thread drift. Start a new thread with something like " VVT spark advance table question"

wkndracr 03-03-2015 02:45 PM


Originally Posted by emilio700 (Post 1211735)
Yikes. What octane/state?
Without seeing your VVT table, I'd guess you're about 5° too much advance everywhere. Have you verified base timing? Restricted intake would not likely lower det threshold unless you're getting a ton of heat soak. Plastic intake pipes will do that.

Anyway, this is a bit of thread drift. Start a new thread with something like " VVT spark advance table question"

Yeah, didn't mean to go too OT. Just to answer your questions, I strictly run 93 octane in NY/NJ. I have verified the base timing, although not for a while. VVT table is the base map that comes with the VVTuner. I only mentioned the intake because since it is quieter now, I can now hear pinging that I may not have been able to hear before. I adjusted the table down about 5 degrees across the board after looking at a bunch of others I found on the site. I'll reflash when I get out of work and start a new thread if I have anymore questions. Thanks!

Savington 03-03-2015 03:39 PM

Zoinks. I would pull 10 degrees from that at WOT until you can verify the tune on a dyno.

Morello 03-15-2015 12:04 PM

Do we just ditch the little inductor /capacitor on the back of the vvt engine? 94-97 injector/ignition harness doesn't have a plug for it . I'm going to be working on this all day today.. If someone who's done this is willing to let me text /call them with questions as I go I would be eternally greatful :D

curly 03-15-2015 12:23 PM

Yes, you ditch it. There's a similar unit on 1.6s on the ignitor bracket. Not sure if they're pnp though. Or if they do the same thing even.

Morello 03-15-2015 03:18 PM

Alright thanks. For now I'm putting the vtcs manifold back on until I can find a square top to put on it. Is it okay to just hook the butterfly actuator directly to vacuum? I don't have the solenoid, and it's normally open. I don't want to deal with trying to delete it since this manifold isn't permanent anyway. Also, the back end of the 02 transmission that came with this engine looks nothing like that one that came out of my car. I can't see how my shifter will fit on there.. The one that came out of my car has the shift rod(?) exposed, the new one is covered and has 4 bolts where it looks like the shifter should attach.

Edit: Maybe I got a 6 speed and didn't know it?
Edit 2: I'm an idiot. It's a 5 speed, just missing the shifter cover shown on this pic... http://teamtac.org/e107/e107_files/p...0_img_7790.jpg

tpc0531 03-15-2015 11:24 PM


Originally Posted by curly (Post 1204080)
I almost wish I did that. I think ribbed belts look much more modern, but I've never had issues with squeaking V-belts like I have with NB belts. They seem much more sensitive.

I had the opportunity to speak with a gates belt rep a while back. I learned that serpentine belts make noise when they are worn out. You can tighten the crap out of them but they will still squeak. There is a thin gauge available to check the groove depth on the belt. Basically, if the gauge is in the groove and you see it, belt is worn out. If a non v belt is noisy, just replace it.

leboeuf 03-16-2015 12:19 PM

1 Attachment(s)
Does anyone know what the pinout is at the 2 pin connector of the nb1 alternator?
I need to know which pin goes to the 1O pin of nb1 ecu (field out).

One of these goes to 12v or something or nothing or ??
One of these goes to my 5v pwm
Which is which? (I know I can open it up and look, but please save me that trouble)
I'll provide this thread with a writeup of MS3 and nb1 alternator control in an NA6 once I have it working
https://www.miataturbo.net/attachmen...ine=1426522794

leboeuf 03-17-2015 11:57 PM

1 Attachment(s)
Found the wiring diagram with the plug pinout. The simple things in life.
https://www.miataturbo.net/attachmen...ine=1426651061

Ziggo 03-21-2015 02:53 PM

"Alternator and pulleys
Use a 1994-1997 alternator and pulley. The 1.6 alternator has a different shaft diameter, so a pulley swap is not possible - the entire alternator must be swapped. It may be possible to use the 99-05 ECU with wiring changes and an ECU with alternator control, but few/no PnP ECUs for 1990-1997s will have this feature, so it's easiest to simply use a 94-97 alternator with onboard control. "

Would it not be possible to use the 90-93 alternator and swap the 1.6 crank and water pump pulleys? Does the 1.6 long nose crank pully not fit on the 1.8?


Great thread. I missed the info about needing a 99-00 fuel rail in my previous research. Will have to come up with one of those.

wkndracr 03-21-2015 04:09 PM


Originally Posted by Ziggo (Post 1217270)

Would it not be possible to use the 90-93 alternator and swap the 1.6 crank and water pump pulleys?

This is exactly how I did mine. 1.6 long nose crank pulley works perfectly.

Savington 03-21-2015 04:51 PM

I prefer the 1.8L pulley that was designed for the 1.8L engine.

Morello 04-05-2015 02:02 PM

So is the solenoid for the fuel pressure regulator used after this swap? If not, can I repurpose the signal wire to control the vvt solenoid?

Savington 04-05-2015 02:18 PM

There is no solenoid for the fuel pressure regulator. The FPR is purely mechanical

Ben 04-05-2015 02:27 PM

He means the hot start pressure up solenoid found on some NAs.

I suppose you could, but with the other rewiring also required with the swap, I don't see the benefit.

Savington 04-05-2015 02:33 PM


Originally Posted by Ben (Post 1221488)
He means the hot start pressure up solenoid found on some NAs.

I suppose you could, but with the other rewiring also required with the swap, I don't see the benefit.

It's been a while since I've seen a stock NA :party:

With this method (99 rail + 93 FPR) you aren't really changing the mechanical properties of the fuel system. It's still an atmospheric referenced ~43psi base system with a single regulator. If you want to keep the hot start solenoid, keep it, if you want to repurpose the wires, you can do that too.

Morello 04-05-2015 03:08 PM


Originally Posted by Ben (Post 1221488)
He means the hot start pressure up solenoid found on some NAs.

I suppose you could, but with the other rewiring also required with the swap, I don't see the benefit.

The idea would be to avoid running a wire all the way back to the ecu. Can I tell the megasquirt that the vvt solenoid is on that pin and use the stock harness? According to the 95 wiring diagram, it goes back to pin 2r

Also, what is the best way to route the crank position sensor wire?

Leafy 04-06-2015 08:22 AM

Well if he's following this swap and using a standalone, the ecu wont be controlling that noid. I'd go ahead and use the wiring.

Ziggo 04-06-2015 09:18 AM

You won't be able to "tell" it to use that pin, but you could crack open the case and rewire the VVT output to that pin.

For the Reverant MS3 I am buying I am just going to run an extra bundle from the DB37 to the bay with VVT, VICS, VTCS and injector 3/4 in it.

Midtenn 04-06-2015 01:11 PM


Originally Posted by Ben (Post 1221488)
He means the hot start pressure up solenoid found on some NAs.

I suppose you could, but with the other rewiring also required with the swap, I don't see the benefit.

I used the wiring from the pressure up solenoid in for my VVT solenoid (see earlier responses). I did it because the pressure up solenoid (a switched 12v+ and trigger) was already a part of the injector wiring harness. I just added the VVT pigtail to the existing wiring and moved the trigger wire on the ECU side (AEM EMS). It was a lot easier than having to patch into the 12v+ from the injectors and run a new trigger.


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