Repurposing MSPNP9495 EBC Output Pin for VICS
 

Planning to repurpose the EBC output for the OEM VICS solenoid on a normally aspirated car. Anyone know if the MSPNP9495 circuitry will be OK with the solenoid? Ben?

Sure, the circuit can sink plenty of current.

Thanks Matt.

I'm almost there . . . everything's wired up and ready.

I set X4 function to Output1. No sweat.

Now I go to the Outputs dialog to setup Output1. It wants the value as a raw byte (0 to 255) even when I setup RPM as the source. Anyone know the conversion from RPM to the raw byte?

Sorry for being an MS1 dinosaur, but the 1st gen MSPNP came with the car.

why not use the EBC function, and just populate the rpm/tps duty table to go from 100% to 0% at 5252RPM?

Does it react that fast? (Genuinely don't know, just asking)

Will the EBC function work properly with signal ground? Thought it worked via 12v pulse. (Again, genuinely asking)

Because I'm retarded. :loser:

Darn good idea. Will do. :brain::brain::brain:

Yes, instantaneous (or as instantaneous as a PN junction in a transistor can be).

The circuit, whether you're using it to PWM an EBC solenoid or as a simple discrete output, provides either an open-collector (i.e., no continuity) or ground. That's why you supply switched 12VDC to the other side of the device (normally the other side of the EBC solenoid . . . in this case the other side of the VICS solenoid).

Ah ok that makes sense. I learned a thing today! :)

More info
 

I followed Brainy's logical suggestion to use the open loop EBC function for VICS control. The idea is that this would let me make use of the built-in RPM settings. This is how I set that up:
https://www.miataturbo.net/attachmen...1&d=1407354845

https://www.miataturbo.net/attachmen...1&d=1407354845

https://www.miataturbo.net/attachmen...1&d=1407354845

By setting my targets more than 20kPa away from what a normally aspirated car would ever see, the MS forces open loop and reverts to the duty cycle table. The duty cycle table is setup to switch the VICS at 5200RPM per the OEM specification.

Unfortunately, when I logged some pulls I found that this wasn't working. VICS was always deactivated above 5200RPM as desired. But below 5200RPM, VICS only turned on if MAP was above 90kPa.

In this pull, I keep MAP well above 90kPa and get a nice switch at 5200RPM:
https://www.miataturbo.net/attachmen...1&d=1407354226

In this pull, I generally keep MAP just below 90kPA and the VICS stays deactivated the whole time (except for one small noise blip above 90kPa):
https://www.miataturbo.net/attachmen...1&d=1407354226

And here's a picture of the kind of havoc that was being created with the VICS output in normal driving:
https://www.miataturbo.net/attachmen...1&d=1407354226

Looking at the MS firmware, I found code that disables the EBC output whenever you're not in boost. The comment in the code indicated it was meant to keep the EBC solenoid from wearing out. Whatever. Bottom line, on a 1st generation MSPNP, using the EBC function for VICS is not workable without a firmware change.

So I decided to use the "Output 1" function instead of the EBC function. Here's what that looks like:

X4/JS2 is changed to Output1 instead of Boost Control.
https://www.miataturbo.net/attachmen...1&d=1407354845

Then you setup the parameters for Output1. When you select RPM as the parameter, the numbers you specify are RPM / 100 (i.e., 52 is 5200RPM). You can also specify a hysterisis (I used 1 or 100RPM) to prevent the VICS solenoid from oscillating. Select inverted operation. With these settings, the VICS deactivates at 5200RPM on an RPM increase and activates at 5100RPM on an RPM decrease. Proper operation was confirmed by observing the "Output1" icon on MegaTune/TunerStudio and by physical observation of VICS actuator movement.
https://www.miataturbo.net/attachmen...1&d=1407354845

YMMV.

TL;DR - MS1 EBC function can't control VICS correctly.