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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/)

Quote:

Originally Posted by Savington (Post 1472777)

The '97 has three wires, but the third wire is a shielding ground for the other two. You could theoretically pass 12v up one of them, the signal up the other, and then wire a new ground as well, and then change all the pinning at the ECU, but fuck that.

That's what I figured. I'm trying to keep as much of the OEM harness stock as I can, but it obviously doesn't make sense if it requires more modification. So in this configuration, the stock crank sensor wires are not used at all, right?

Quote:

Originally Posted by Itty (Post 1472853)

I do not believe the stock crank sensor wires are used since they are all extended from the CAS plug - Someone please correct me if i'm wrong, wouldn't be the first time i fuck up wiring.

cut the factory plug off and extend the +12v and ground wires to each of the NB sensors.

12v (extend 90-97 wire to both 99-05 sensors):
90-97: White/Red

Cam (extend to Cam sensor only):
90-97: yellow/blue

Crank (extend to Crank sensor only)
90-97: white

Ground (extend to both 99-05 sensors)
90-97: black/light green from CAS plug to

From cas plug to CAM and CRANK 12v+/Ground/ ONE SIGNAL

and all of the other changes necessary will happen in the firmware/software of your ECU.

Just got my dyno sheet back from my tuner. Car is a 91 w/ stock 1.8L VVT. 93 Octane, RB headers, ebay catback, Skunk2 IM, MS3X. Power number seems spot on, torque is a bit low but at least it's stable. Run 1 is the baseline map with a few adjustments by me. It's worth noting this is on a Mustang dyno.

https://cimg1.ibsrv.net/gimg/www.mia...3223eca339.png

Quote:

Originally Posted by Goingnowherefast (Post 1474248)

torque is a bit low

Quote:

Originally Posted by Goingnowherefast (Post 1474248)

Skunk2 IM

Quote:

Originally Posted by Full_Tilt_Boogie (Post 1474250)

Oh you're preaching to the choir. I'm sure it had something to do with it. But, looking back at the numbers (being a mustang dyno) it seems quite comparable to the other VVT dynos in torque when you factor in an 8-12% correction factor.

Being a VVT swap, the Skunk 2 IM is a much better choice being as it relieves any clearance issues between the fuel rail and flipped regulator setup that you have to run. That being said I will gladly accept square top donations :)

Before I bought the motor one cylinder had ~30psi lower compression than the others. Haven't re-checked (and more or less don't care) so I'm real happy with the numbers.

Quote:

Originally Posted by e1_griego (Post 1474469)

I had mine tuned by Kris at KO Racing last weekend.

2002 VVT with ~124k miles, RB header, Enthuza catback, Fujitsubo exhuast, NB1 VICS intake manifold, 3d printed intake. Tuned on MS3 pnpPro.

Before I bought the motor one cylinder had ~30psi lower compression than the others. Haven't re-checked (and more or less don't care) so I'm real happy with the numbers.

Pics are kind of hard to see. What kind of numbers did you put down? Curve looks great.

Shit, sorry.

137/127.

I'll see if Kris can send me the files instead of potato quality pic.

So I searched through this thread and didn't find anything definitive, or I might have missed it. So here's a question.

I picked up a VVT engine to put into my '94, and it came with the entire engine harness. For a race car application, if I had a plug and play ECU for the VVT harness, would swapping harnesses be the easy button? Or would it cause other issues or need adaptation at all?

Again it's a race car application and won't have a stock gauge cluster so if none of that works, doesn't make a difference to me.

It's going to be way more work to pull the stock harness and install the VVT harness than to adapt the stock harness to run the VVT.

When I did mine, I used a non-PnP MS3, and just adapted the stock VVT engine harness to the MS3 with connectors at the firewall, and connected the few wires needed for the gauges into the stock harness.

Quote:

Originally Posted by Arca_ex (Post 1474529)

The two relevant posts you missed:

Quote:

Originally Posted by Savington (Post 1377767)

My current customer project is a customer who I built a motor for last year. He decided to have another shop assemble his car, including the VVT swap (motor is a 02, car is a '97). The shop doing the swap attempted to swap the complete harness, including chassis harness, from their donor '02 into his '97. When they couldn't figure out how to get it running, the customer asked if I would be willing to take over the project and get it figured out.

If you got this far into this thread, and you are still considering a full harness swap, I have one word of advice for you: Don't.

Quote:

Originally Posted by Savington (Post 1378108)

The stock ECU is plugged in, but since they only swapped half the NB fuel system in (front half), it never would have worked anyway. I'll be using an MS3 Basic for an 01-05 harness. It's not even the harness swap that makes it difficult. The NB fusebox is taller and requires a custom bracket. Still not sure how I'll mount all the relays that sit behind the NB fusebox. The headlights will never work again in this car since the motor relays left with the NA harness. No NB dash harness, so no wipers, turn signals, headlights, or HVAC. Thankfully the brake light switch connector appears to be the same. The entire fuel system is different, as I mentioned. Fan wiring is wrong, thankfully the SPM rad in this car can accept NB fans (shop lost his fans, so we'll replace). Keep in mind that this was sourced from a complete donor, so I have every relay/box that came with the '02, If you are buying a bare '02 harness and expecting to make it work in your NA, forget about it.

I wouldn't even try to estimate the number of hours of work it would take to make this work in a street car. I almost ripped the harness out and bought a new 94-95 harness to start over with (easier to get an ECU for), but the '02 harness was already in place and mostly plugged in, so it was faster to fab up custom brackets for a few things vs. re-strip the car and start over. It will still cost him a couple of thousand dollars in diagnostic and corrective work to get it running.

To put it succinctly, it is one of the worst ideas I've ever heard.

Well that settles that then. Have a cat.

I'd like to start by saying thanks for all the info in this thread without it I wouldn't be this far.

I have a vvt swapped into a 93 per this thread with a used mslabs ms3. it is basically complete using the nb tps and throttle. I am havin a weird issue with my tps. At initial throttle input it will show negative throttle postion. Sometimes like 30% in tunerstudio. This is approximately .25" or less of pedal travel. It also does not settle back to the same zero consistently.

I thought it was the sensor so I bought a new one from autozone and the problem persists. I double checked the wiring looks correct.

Any one have this issue before?
Am I missing a ground or something?
what should I diagnose next?

any help is appreciated.

if it matters
lc2 wideband
swapped in abs at same time
car does start, but throttle signal makes it hard to drive

So do I not have a 99-00 fuel rail or is this not a 90-93 FPR? I’ve bent the FPR as much as I feel comfortable bending (it’s startig to crush itself) and I still cannot imagine this setup fitting...

Quote:

Originally Posted by Stock (Post 1478292)

NB1 has the FPR at the end of the rail. NB2 has it underneath (like yours)

That being said I'm surprised how close that actually is

Damnit. I'll dig out the NB2 rail that came with the engine to confirm they're the same. Bought this from a Miata recycler on FB, hopefully they'll make it right.

That looks like an NB2 rail

Quote:

Originally Posted by Neilv (Post 1478296)

That being said I'm surprised how close that actually is

Note how it's not even close to being bolted to the head, though

Yes, it’s an NB2 rail, they’re shipping an NB1 out tomorrow.

And no, it isn’t even kind of close.

So thinking about upgrading to Toyota COP's from a local that had a 1.6L kit made. Plug in play since he bought an additional igniter.

Can anyone confirm if Toyota/Denso COP's will physically fit in the VVT motor without a bracket? Is a bracket even needed?