DIY LTCC or similar system for LT1s

**vilefly** · 10-03-2017

Sure thing Johnny. I have an arduino mega 2560 ordered from ebay. Might help me follow along. Should have enough memory for spark tables. I am hoping we might be able to transfer spark tables over from a flash binary file(s), and run the northstar module with it. I still need to concentrate on my hardware decoder......am having issues finding surface mount chip adapters at a decent price, so that I can do some proper prototyping.

I am also working on a bolt-on reluctor wheel that was posted on another site, but they never released any final forms or brackets, so I have to work up my own. The waterjet cutting company is willing to do business with me and have decent prices. Now, I just have to figure out the layout for the sensors and base timing. That will be much later on. But I will post the DXF files publicly.

Hooking an arduino up to the ignition module with its own spark tables would be neat, but I have to do my part 1st. Not sure about knock detection on an arduino, though. Which is why I want to use Ion Sense Ignition so knock detection does not require a tuned knock sensor/software.

WAIT! Damn it. I am over thinking this....you can hook up the OEM ecm to the northstar module's EST input directly, since it is still getting a signal from the optispark. NO LOSS OF FUNCTION. The ignition module will still decide which coil to fire + dwell, and the other outputs need not be connected at all (to the ECM). That is how Deltec did it! Would need a harness to prove it, but not really. As long as the crank signals are adapted for the northstar module, it should be fine. Will have to tie the BYPASS input to constant 5v to put it into constant EST mode like the original ignition module, but it has no reason not to work.

**johnny_b** · 10-04-2017

Originally Posted by vilefly

WAIT! Damn it. I am over thinking this....you can hook up the OEM ecm to the northstar module's EST input directly, since it is still getting a signal from the optispark. NO LOSS OF FUNCTION. The ignition module will still decide which coil to fire + dwell, and the other outputs need not be connected at all (to the ECM). That is how Deltec did it! Would need a harness to prove it, but not really. As long as the crank signals are adapted for the northstar module, it should be fine. Will have to tie the BYPASS input to constant 5v to put it into constant EST mode like the original ignition module, but it has no reason not to work.

I like where you are headed. Wouldn't this mean we would have to change the signal coming out of the opti to match the northstar?

There is a junkyard no more than a mile from my house littered with northstars, if you need any northstar stuff let me know. Does this mean we will only be able to use the waste-spark style coils?

**vilefly** · 10-04-2017

Originally Posted by johnny_b

I like where you are headed. Wouldn't this mean we would have to change the signal coming out of the opti to match the northstar?

There is a junkyard no more than a mile from my house littered with northstars, if you need any northstar stuff let me know. Does this mean we will only be able to use the waste-spark style coils?

To mimic the deltec exactly, we will definitely have to adapt the opti signals to match the northstar's 2 crankshaft sensors, minus the cam signal. It is confirmed that they wired the EST and BYPASS exactly as I imagined. The signals will have to be above and below the zero volt line because of a zero crossing detector built in. So about +5v/-5v peak to peak should work fine.

This would work only for the waste spark setup type coils, unfortunately. But it would get you distributorless. I have a spare northstar ignition module with a bad (shorted) EST input. Just enough to test a signal generator and my crankwheel setup later on. I wonder how much the junkyard would want for one without the coils on it?

**johnny_b** · 10-04-2017

I can grab some northstar ignition modules no problem, i bet they would only be a few bucks.

The waste spark setup is perfectly fine.
Northstar's have a different firing order than sbc.
looking at delteq's Ignition module that the coils seat on, I wasn't sure if this was the factory northstar module or they perhaps made their own.

Just so we are clear, what I have pictured below is the Ignition Module correct?

**vilefly** · 10-04-2017

Yup. there is only one like it. You might want to grab the pigtail connectors to it as well.

**johnny_b** · 10-04-2017

Originally Posted by vilefly

Yup. there is only one like it. You might want to grab the pigtail connectors to it as well.

I will grab a few on saturday and report back.

So from what I understand about the northstar module, it only ever needs 2 of the 3 sensors to actually function. either both crank signals 27* degrees out of phase I think? or one crank sensor (think its 24x?) and the 1x cam sensor. Having all 3(both crank and the cam sensor) allows for faster start?

It seems maybe the 1x cam signal would not be that difficult to convert to with the factory opti-wheel signals?

**vilefly** · 10-05-2017

Originally Posted by johnny_b

I will grab a few on saturday and report back.

So from what I understand about the northstar module, it only ever needs 2 of the 3 sensors to actually function. either both crank signals 27* degrees out of phase I think? or one crank sensor (think its 24x?) and the 1x cam sensor. Having all 3(both crank and the cam sensor) allows for faster start?

It seems maybe the 1x cam signal would not be that difficult to convert to with the factory opti-wheel signals?

Well, what I am not sure of is exactly where in the rotation that the cam sensor sends its quick 1-pulse. Maybe 67.5 degrees after the 1st pulse from the leading sensor. +/- maybe 2 degrees. I am not sure if the ignition module can run on one crank sensor and one cam signal, but it would be cool. We might be able to cheat. If a cadillac comes in sometime, I will grab a better scope pattern from it with pulsewidth measurements if possible.

You know what? I think I will make a round slide rule that will fit inside of a cd case with a 27 deg set of spaced windows so I can check my synchronization at any time. Am sick of getting out the ruler and protractors. Might help me think clearer amidst distraction.