Hi,

My question is about wiring to a 13B CAS.

I am planning to purchase Megasquirt in the very near future to run a S5 RX7 TII 89-91 13B turbo engine. I want to purchase a Megasquirt 3 ecu, PCB 3 and the MS3X expansion.

My understanding when reading various sources of information is that the rotary engine's CAS has two Variable Reluctor (VR) circuits, and I think that one needs to connect to the MS3 PCB, and the other to the MS3X PCB and I assume that means each VR needs to connect via seperate wiring looms.

So I think that means I need to therefore need to run 2 seperate 2 core shielded cables, which I'd rather not do, as it means I'll be tying the two MS looms together

Is there a way to elegently bring the CAS signals into one connector on the MS via a 4 core shielded cable?

Thanks in advance,
Arran

 

I emailed Matt at DIYAutotune about wiring the CAS and received this reply:

Correct that the MS3 and MS3X each have one VR conditioner. There's no good way to move I/O from one harness to the other; most of the MS3 and all the MS3X wires are determined by PCB.

 

I used full function engineering trigger kit. It uses only one sensor and has great resolution compared to stock. Since I swapped to that I have had 0 noise or trigger issues. I am running rew engine but the over a kit for both.

 

^Did you use the VR or Hall sensor version? Other than changing the wheel type in TunerStudio did you have to do anything special to get leading and trailing to work correctly?

Looks like it's well made, might have to get one!

 

The wheel settings changes should be all that are necessary from a firmware settings point of view.

Ken

 

They have the setting listed on their site. Great guys to deal with also.

 

Which is the best place to connect the added shielded 2 core? To a random ground, to a megasquirt ground or to the grey shielding wire from MS3 that the single shielded wire uses?

 

I generally ground the 2nd VR input directly to the ground on the LM1815 circuit. Then the shield to one of the grounds. A moot point with an MS3X and single trigger sensor because the 2nd VR isn't used.

 

You talking about the ms3 board crank ground?

 

To be honest I don't know what I'm talking about because I'm not sure I'm following the discussion.

The ground side of the VR signal should ideally be grounded closest to whatever circuit is receiving it. So 2nd VR should ground to MS3X, primary VR should ground to the main board.

 

Thanks, i did kind of jump over the wheel trigger kit. I was refering to cas sorry.