Cam and crank sensor setup with VVt
 

So here is a question I feel is answered, but I cant find it.

I've got VVt head on an NA block with MS3x. I'm starting to understand what I need to do but havvent completly figured it out yet. I've got a 12-0 TSE trigger wheel with the NB crank sensor.

What do I need to do with the cam timing.

https://www.miataturbo.net/attachmen...ine=1329535504

Is this correct. Can I ditch the CAS, and only use the cam sensor on the top of the valve cover? Is the cam sensor the hall effect sensor yall talk about? Do I need to modify anything to do this? i.e. cam teeth?
I'm reading something about grinding teeth off the cam, to leave only 1 tooth.

I understand I can grind a tooth off the crank wheel, and ditch cam timing all together, but I'm trying to do full sequential.

You do not need the NA-style CAS at all. You can remove it and plug the hole, or leave it in place disconnected.

To the best of my knowledge, the TSE 12 tooth wheel is not useful for running either full sequential or VVt when used in conjunction with a stock NB2 cam using an MS3. This is a software limitation, simply because nobody has written the code that would be needed to run this rather unusual combination. If you were to remove two of the three teeth from the cam then you could run sequential injection and ignition with the 12T wheel, but still not VVt.

To run both full sequential and closed-loop VVT control, you need a stock (4 tooth) NB crankwheel and the stock NB cam sensor. You don't need to grind any teeth off of anything in this scenario.

^ This. Remove TSE wheel, put the stock back in, ditch the CAS.

Joe/Jim, has anyone written MS3 code for a K20 that could be adapted? We're toying with the idea of offering a 12+1 version for VVT guys.

Without checking (sorry), does the MS3x VVT code support a 12-1 or 36-1 trigger wheel (combined stock cam nubs and stock cam sensor)?
The VVTuner only support the stock setup, but maybe the MS3x code would allow higher precision?

Making a 36-1 trigger plate for the stock sensor would not be hard (some steel and laser), but without software to make use of it the idea can be left in the drawer.
The shipping cost of a wheel of that design would not be more than for a CD, so there could be a simple market for them (make 1 or 20 would cost about the same).

PMed.

Best bet is to log onto msextra.com's forum and post the setup you want to make work in the VVT thread and they can just code it in. Probably can release it with the next alpha.

You want to use the 12-1 with the stock NB cam sensor, right?

To y8s you listen.

Programming this, in theory, is not a terribly difficult task. Within the MS2extra code, for example, here is the definition for a '99+ Miata:


It's just a matter of getting one of the developers sufficiently interested to actually do it.



Any MS (MS1, 2 or 3) will support a 12T or 36T wheel, either by itself with a missing tooth in batch mode, or with a cam signal which provides one pulse per revolution to allow full sequential operation (sequential fuel only available on MS2 and 3.)

This can be done simply by using the generic wheel decoder mode.

The problem comes when using cam wheels with more than one tooth or any wheel with unevenly-spaced teeth. Such configurations are too complex to be described in the generic wheel menu.

So if you grind all but one tooth off the cam would it work without modifying the crank wheel and keep sequential?
I already got my TSE wheel machined to fit over my ATI, and I don't want to have to do a stock nb wheel also unless I have to.

Ditching sequential is. It an option.

VVT won't work as-is with the TSE wheel.

I want to keep the 12-0. From what I read, grinding any teeth off the crank wheel results in loss of sequential, am I wrong?

I understand that, but what about modifying the cam triggers?

No, code modification in the ECU is still required.

honesty the adaptronic setup for custom triggers was pretty impressive. you basically had a toot table and you just enter degrees where each tooth was. it was complicated as F but at least you could do it.

You guys are going to hate me, but I don't at this time see a reason to ask James and Ken to write a decoder for 12-1 VVT app. Why? Because the wheel doesn't exist commercially. Sure, you can make one from a TSE wheel, but the problem is that everyone would need to lop off the same missing tooth and clock the wheel in the exact same position for the decoder to work. That's not going to happen, it's going to be a nightmare to support, and it's only going to benefit few people.

If TSE were to stock a 12-1 with keying to install only one way (or at least alignment marks), I'll ask the guys about it. But from where things are right now, we have a lot of other features to work on. The 12+1 may also be a viable option, and theoretically may provide for more precise command, though I'm not convinced there's measurable benefit in reality.

There's no reason why you can't grind one tooth of the 12 tooth wheel, then grind 2 teeth off your cam gear. That will give you a pattern that is supported for sequential and VVT, and will allow you to set your tooth #1 angle specific to your engine and where you cut your teeth.

You can not use the 12-0 wheel and stock cam trigger with the MegaSquirt. There is no wheel decoder written for that application. For batch fuel and no VVT control, you can remove 1 tooth from the 12 tooth wheel and ignore the cam wheel. For sequential and VVT control, you can remove 1 tooth from the 12 tooth wheel and also 2 teeth from the 3 tooth cam wheel.

Or you can use the stock NB 4 tooth crank wheel and stock 3 tooth cam wheel.

Quoted for emphasis.

I only suggested it because I remember "custom trigger options" coming up in a thread on msextra.

And if you use the VVT head, there's no cam gear from which you grind teeth. The teeth are on the cam and that's a lot less trivial.

Good point.

The stock trigger patterns will work great.

How tough is it to change because a stock CAS set-up and a stock NB2 set-up?