Distributorless

I'm trying to search, but site won't give me anything useful on short keywords like DIS. So, what I'm trying to do, actually to research, is about using distributorless ignition from 00/01 on older XJ.

Somebody mentioned that there was thread about it, but I can't find it.

Anyway, what would be involved in it? In theory, what I can see, is that I need this rail, which is triggered electronically, and I would need something - some sensor that goes into where my distributor is at the moment. That sensor would be used to pickup the angle, and later help the electronics to select which spark to trigger. Correct?

you will probably have to run a 99+ engine (i may be wrong) since before that they used a distributor(obviously)

Sure, that would be the easiest way. But why don't we all run stock tires, axles and gears? No fun at all!

Idea is to put DIS system to older engine, like renix for example.

Swap over the control setup (OBD-II/DIS) from a later Jeep. You should be able to work with 2000-2001XJ, or 1999-up other models with 4.0L.

You can either leave the distributor in place and disconnected, or pull the "distributor stub" as well - you need something in place to drive the oil pump (since it's driven off of the camshaft, by a tang on the bottom of the distributor shaft.)

However, I'm certain you're going to need the full electronic setup, since the "distributor" setup is programmed for one coil (while the DIS setup uses three, I believe, in a "waste spark" setup. That means that two cylinders are fired at a time - one at TDC compression, and one on the exhaust stroke.)

According to '00 fsm that I'm looking at, there is Camshaft Position Sensor: "The Camshaft Position Sensor (CMP) on the 4.0L
6–cylinder engine is bolted to the top of the oil pump
drive shaft assembly ", so whatever it does, it needs to be there.

Also, it would be trivial to use old distributor for low voltage ignition signal from ECU to drive coil rail. What fsm is saying, that there are 3 coils inside rail, and they are indeed used in wasted spark system. I would connect distributor outputs for 1-6, 2-5, and 3-4 to corresponding individual coils on rail.

In theory, provided that signals are the same (00 rail wants input to be pulled to ground to fire sparks), it should work. However, what would I gain from such setup? The thing that I don't like with classic distributor is very high voltage involved with rotating parts and moisture. Would this kind of hack give me any benefits?

Ive had mine deep in water,it loves it.The rail is basically a sealed unit.Like you said,no moving parts to get wet!

It might. One of the advantages that DIS or COP (Coil On Plug - one coil for each plug) is supposed to have is greater saturation time for the coil before firing - so you can get a more energetic spark. Even with a DIS/Waste Spark setup, there is some merit to the idea.

I'd be interested in seeing if the CAM sensor atop the "drive stub" for the oil pump operates on the same principle as the CAM sensor mounted in the distributor - more for academics' sake than anything else. If you're going to do the job, might as well do all of it - but this could tell you about "intermediate stopping points" while you're trying to get it done.

But, you shouldn't need to use distributor outputs to drive the coil rail - and besides, isn't there a certain voltage threshhold you'd have to make for the spark to jump the air gap under the cap? That may obviate your idea to use the distributor for LV triggering of the coil rail as a primary signal...

Now how did I forgot about that sensor that we also have on renix? It can be used for sure!

I'm not really sure about this gap in distributor? Is there supposed to be a gap, or it makes mechanical contact?
Now in both cases, idea is to get rid of mechanics at all, and rely on electronic signals from sensor below.

Fsm says that it generates pulses with respect to cylinders 1 and 6, does it mean that I wouldn't have a clue is it 1 or 6 when I see it, or something else?

While it does have 2 screws(like you might be able to get into it),its not very big.Id bet on a "hall effect" switch,cant see it well but it looks like it has 4 wires.It is not permanately "indexed"

I think this would be a very cool setup to do on an older engine

I think now that it might not be important if pulse from camshaft is at #1 or #6 or both.

When I get pulse, I reset counter.

on ignition pulse I triger coil #1 which sparks on 1 and 6,
then on next ignition pulse, I will trigger #2 which will give me 2 and 5,
on next one I trigger #3 which sparks 3 and 4.

Then I get pulse again, and reset counter and everything goes from beginning.

Given that firing order is 1,5,3,6,2,4 it does work what its supposed to work either way, be it reset on 1 or 6.

It seems that there IS some logic behind what Chrysler did in 10 years