RusMan

You guys seem to know everything so I thought I'd ask you guys.
I'm finally stepping up to a standalone, and have an Autronic SM2 EMS system that I will install on my fresh engine.

So I have a little question about the stock sensors. Are they the hall-effect or magnetic(inductive) sensors? The wiring needs to change quite a bit depending on the type so I want to make sure I got them correct. Basically need to know if they sensors output a spiky wave signal or a square wave.

Any help is appreciated.

Joe Perez

iTrader: (8)

Technically they are VR sensors, however they contain active signal-conditioning electronics and their output is an open-collector driver which produces a squrewave when provided with an external pullup voltage.

RusMan

Thanks for the reply Mr. Joe
I feel kinda dumb right now (too much reading) but this doesn't make much sense to me at the moment.
"external pullup voltage"? Is that something that I have to do or how do I get that.
Here's what my manual says:
"When using inductive sensors a reluctor interface is required(little box). This interface will make a square wave from the small spike generated from the inductive sensor."
Hall effect sensor on the other hand does not require this interface and can be wired in directly. So basically, do you think I need to run this box or will stock sensors provide a square(hall-type) wave to the ecu?

Joe Perez

iTrader: (8)

Pullup just means that the ECU has to provide a current-limited voltage to the sensor. Don't worry about it, this is an industry-standard thing and I'm sure even the Aussies have figured it out and built it into the ECU.


VR (variable reluctance) sensors are nothing more than a coil of wire wrapped around a magnet. When a metallic object passes through the magnetic field, it generates an AC waveform. This is, in fact, exactly how a generator works. Unfortunately, a CPU wouldn't know what to do with an AC waveform, so you have to rectify and condition it. With high-end ECUs like the MS1, this function is built in, but I guess the EMS requires an external conditioner.

But it's irrelevant, because the Miata's sensors have all this circuitry (the external box) built right into them. Wire 'em up as if they were hall-effect sensors. They're not, but they produce the same output as one.

(The reality is that true hall-effect sensors are essentially obsolete in the automotive community. The vast majority of OEMs use VR sensors with internal conditioners. However it's confusing to think about, so most folks go on calling 'em hall sensors simply because they produce a hall-sensor-like output. An actual hall-effect sensor can be identified by the presence of several small magnets on the surface of the object being measured. But I think I'm getting into TMI at this point. )

RusMan

Alright, I really appreciate the detailed explanation and couldn't thank you enough for it.

It all kind of makes sense now. I will try to wire it up as is and see how it turns out.


Now I just need to figure out my ignition setup...