MicroSquirt.com read only forum (Jan.15,2018)

I'm planning to use either MSII or MSnS on my 1995 3000GT VR4, but I'm a little confused about my ignition options. I have the CAS from the 93-99 years as seen in the detailed explanation on this page:
http://stealth316.com/2-ignitionsystem.htm#j2b

As I understand it, here are my options:

Option #1 (Wishful thinking): Use my stock CAS without modification. I can't seem to find any info on this kind of setup in the MegaManual, so I doubt it will work.

Option #2: Convert to the 91-92 setup from the page above
I think I read that some folks were able to trigger from discs like this.

Option #3: Write custom code
I don't want to, but I'm capable of it.

What do you think is my best option? BTW, I definitely prefer the MSII because the CAN interface and the C codebase. I have boost controller plans for the CAN ;)

Thanks in advance

ok, just to save you from clicking the link, I've attached the files.
Anyone know if this will work without modification?

If not I think I will build a small board to read both signals and provide something easier to use with the MS. Probably I would output the CAS and a single pulse for piston 1 TDC. Something like an AVR micro running at 1MHz would be plenty fast and powerful to do that.

===>DavidC

I read most of the article in the link you attached. Here is the line you need to be concerned with.

"As shown in the figures below and for all model years, the CAS outputs 3 pulses for every rotation of the crankshaft and the TDCS outputs 2 pulses for every crankshaft"

The article says the 91-92 years use photo led sensors and the 93- use hall effect sensors. From the stand point of getting a signal to the MS, either sensor will work. The MS can read both of them. As far as configuring the MS for a 3pulse 2 pulse signal. I'm not sure about that. Other people in here can answer that question.

You might consider a crank wheel sensor. They will work with the MS and they are much more accurate. It might be easier to mount one on the crank pully than to rewrite the code.

right - i'm not too concerned with the electrical characteristics of the signal, it's mainly the weird TDC stuff.

Anyhow, I've written code and am just about ready to go with a board that would go between the CAS/TDC and MSnSE. I am naming it MegaSignal ;).

It converts the signal in the diagram above into a 3/1 signal. 3 falling edges per crankshaft rev at 75 BTDC, 1 rising edge on each crankshaft rev at 75BTDC to indicate piston 1. The piston 1 indicator is the same length and timing as the other pulse signal, just inverted and only occurring at piston 1 75 BTDC. I'll post a diagram later.

SOMEONE PLEASE LET ME KNOW IF I CAN'T TRIGGER THIS WAY! I think it should work.

I'm giving it the name MegaSignal because I plan to expand it to be configurable for other similar scenarios.


Why am I doing this instead of putting a toothed wheel on the pulley? Because there isn't much room for mounting a sensor or a wheel, plus I want it to be a nice clean stock look.

hey keep us posted on this. I have a friend with a 92 VR4 we are debating running MS-II. He wants to get rid of the MAF and go SD.

Attached is the timing diagram of my board. Can anyone confirm this would work?