EpitrochoidalPower!

So...the guy who was supposed to fit and tune and ecu to my car is all out of parts and isnt going to have any for some time. So, i've decided to get a megasquirt II and fit and tune it myself (done everything else myself so far might as well do the computer too).

So what I need help with is:

1. Should I buy an assembled megasquirt or should I assemble myself.

2. What extras will I need to run my rotary setup, because im in South Africa which means i'll have to order from the states and I want to make sure i get everything ill need first time. (see setup below)

These are my main concerns...fitting it to the car and/or assembling it wont be too difficult i don't think, my problem is making sure i get and know how to add all the extra stuff that will make sure it works properly on my engine.

My Setup:

1. 13B Bridge Ported engine (was s4 turbo converted to N/A)
2. Twin throttle bodies (efi hardware from tweakit)
3. 4 x 550cc denso injectors (from turbo engine)
4. Standard 12A distributor and coils (from later model 12A i think - comes from 1985 car)
5. Haltech Throttle Position sensor on d-shaft of throttles

So what sensors, wiring, modules, etc etc would I need to give me ignition control and a working engine. I want to get this right first time. If i have to assemble it myself I dont mind i just want to make sure i have all the boards and bits ill require and not have to order over and over.

I was also thinking about running fuel control only and just use the distributor as is for spark. The problem with this however is that im going to be running premix which means id like fuel to be pumped in during the overrun. If I dont have ignition control I wont be able to cut spark during the overrun which im guessing will cause me to have rough deceleration?

Please ask if you need any more info on the parts i'm running. Sorry for all the questions but im struggling to find info relating to the megasquirt being used on a rotary with my ignition setup.

Also, I still have the denso CAS from the turbo motor but don't have any of the other ignition parts, could i somehow use this with my 12A distributor and/or coils to make ignition setup easier?

Any help would be greatly appreciated.

muythaibxr

That's up to you, but I generally recommend doing it yourself. If you're decent with a soldering iron, you end up knowing the board much better, making it easier to do the necessary mods for a rotary, and easier to fix any problems that crop up.

If you want ignition support, I'd recommend going with the 2nd gen 13B coilpacks and CAS. The MS supports those, and they'll probably provide a better spark than the dizzy. Dizzy setup is easier though if you don't need the MS to control ignition.

If you were to control the 2nd gen ignition parts, you'd need 3 pullup resistors (2.2-4.7k), and an lm1815 circuit to condition the second trigger signal, and some 18-20ga wire for internal wiring.

Again, if you want ignition control with the MS, you'd be better off getting a 2nd gen ignition system in there. The MS works with that with no problem. I'm fairly sure that the MS won't control the 12a ignition system for both leading and trailing. I wrote the trailing code to work with the 12+1 wheel setup in the 2nd gen CAS.

For wiring, you'll want to get one of the wiring harness kits from DIYautotune, or RSautosport. As for sensors, you'll want a coolant temperature sensor (Stock is fine), the manifold air temperature sensor (stock is fine, but then you'll want to replace the MAT sensor bias resistor with one between 30kohms and 50kohms). The TPS you have should work fine, and the MS has a built-in MAP sensor so you'll need some vacuum line to run to that.

The MS doesn't cut spark during overrun decel either, so no matter what you'll probably get a bit of popping on decel... if you lean out the fuel enough at that point on the proper part of the VE table, it shouldn't make decel rough, just noisy. Running the MS fuel-only makes setup a bit different but easier... Instead of setting the MS up for a VR sensor with a second trigger, you'd just set it up for coil-negative tach input, and put a resistor inline from the coil to the MS (helps with noise). Someone who's done this should post what value resistor works well, I've only set up for stock 2nd gen ignition.

That's mainly because everyone I know of who's running a dizzy setup isn't using the MS to control it. Also, the MS doesn't support controlling ignition on a distributor-based rotary.

The only way I can think of to use the distributor for rotary support on the MS is to mount some kind of crank wheel on the e-shaft pulley (36-1 would work fine, just about anything would really). Then you'd just wire the leading and trailing using a couple of vb921's, which are then wired to the MS. The MS could probably control this, although I don't know of anyone doing things that way. You couldn't use the CAS with the dizzy since they both stab into the same place on the engine.

Ken