Distributorless conversion

General Megajolt Questions and Answers

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coyotanark
Posts: 3
Joined: Sun Oct 18, 2015 5:54 pm

Distributorless conversion

Post by coyotanark »

Hi

I'm new here and I have a question, I think that some of you have an answer for me.
Here is my situation, I have multiple Ford Probe 2.0l (similar to 626 and mx6's from 93 to 97), 4 cylinders. I have one running greatly for race who had been turbo'ed and managed by a fully standalone megasquirt, DIYPNP that I adapted myself and runs great with a coilpack in wasted spark.
But I have another one (my wife's probe), which is a daily, so almost stock. I'd like to get rid of the distributor, not the whole but mainly the part which distribute the power. The ignitor and the coil are prone to fail, the rotor and cap wear with use and is quite ineffective. I'd like to convert it to a coil pack too, for a better and more durable set up.
But here is the problem, how to know which coil to fire? I precise I don't want to convert it to any standalone system for ease of use, regulations, etc.

The OEM system works like this:
- 2 hall effect sensors are in the disty, one for CMP signal which send 4 signals per cycle, 1 for each cylinder TDC, the other for CKP signal which send 1 signal per cycle, for cylindre n°1 TDC. I want to keep this part as it works well and it's needed by the ECU.
- coil and ignitor are in the disty, triggered by the ECU at the right time, the ECU send the signal after calculation of the advance regarding all of the parameters it gets. The ignitor and coil works as any other, very simple.

But if I want to run a coil pack with 2 coils and 4 towers in wasted spark, I need a system who knows which of the 2 coils it has to fire. I thought about an EDIS 4 triggered by another CKP sensor, but it can't be fired when you want just sending it a signal. You have to create a "SAW" signal, and it makes his own calculations with that... but it'd be to complicated to create this signal from the simple signal that the ECU send.
In fact I only need something who choose the right coil to fire when the ECU "tells" to fire. Can't we trigger this by looking at the injection events, or maybe with the stock hall sensors?

I hope I'm clear, because my english isn't perfect. If needed I have schematics.

brentp
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Post by brentp »

It sounds like you want to make a hybrid of your current ECU and the wasted spark system. The most effective way this has been done is to let the EDIS system handle the ignition 100%, and then feed a tach signal to the ECU so it can see the appropriate RPM signal. If all works well the ECU will think the original system is operating normally.
Brent Picasso
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coyotanark
Posts: 3
Joined: Sun Oct 18, 2015 5:54 pm

Post by coyotanark »

Yes, but you still need to find a way to tell to the EDIS system how much ignition advance you want, and to tell him with the signal it's waiting for. I'm currently reverse engineering my ECU rom, I have to find a way to implement the communication protocol in it

brentp
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Posts: 6274
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Is it possible to install a 36-1 trigger wheel on the crank, or a 72-2 wheel in the distributor housing?
Brent Picasso
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coyotanark
Posts: 3
Joined: Sun Oct 18, 2015 5:54 pm

Post by coyotanark »

I can easily install one on the crankshaft because other later cars with the same engine were sold with a wasted spark coilpack and 36-1. I have a 36-1 on my turbo probe, but it's managed by a megasquirt. My goal is to be able to send a PIP signal to control an EDIS system, like this I don't have to mess with dwell, etc. It'll be easier for an home-made implementation.

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