DIY LTCC or similar system for LT1s

Here are the waveform captures. I was limited on time and scope channels. So, you have proof of #1 TDC on the leading edge. I lined up the cursor on it and the injector leading edge. The trailing edge of the injector waveform never changes position, but the leading edge does with commanded on time. Surprised me how much injector lead time there was.
Attachment 12132
Attachment 12133
Attachment 12134
Even though it says Jeep Grand Cherokee, I assure you it was on my 95 caprice wagon. That was the vehicle I was working on before I ran out to my vehicle to do this.
Whoops! it looked like I left the coupling to the red injector signal on the AC voltage setting. the high line is supposed to be 13.5V, the low dip is close to zero volts, the peak kickback voltage is around 60v.

those scope charts are awesome. is this project going to be something someone can easily home brew?

We should have a number of different choices person could try to see what works for them. Not sure what constitutes easy, but if the code is posted for the arduino version, it should make it a lot easier for someone to try. Mine is a hardware approach at it, since it is all I know. I need more free time to tinker with arduinos and raspberry pi's. I don't think I will be doing much coding, heh. But I will post my schematics, which aren't finished right now, just so I can remember where I left off.

That scope is real fun to play with.
I still need some more info to decode the information.
Is the injector pulse the dip or the rise on the graph and what is measured volts or amperage.
That cylinder pressure thing is also very interesting. Can you gavi some info how it is measured and what tools are needed.

I will ask you to do some more testing to figure out on the hardware level fueling.
There is no points in the code how fuel injectors are fired. Only hint is for ind cyl corr. They are fixed to 3000 rpm and 10% TPS.
Since the TPU controls injectors, the only way to tell injectors are in sequential mode is to monitor the coils with a scope.
Can you do that graph with varying rpm and tps, so we know exactly at what conditions batch mode is used and how PWM are calculated at batch mode if it exists at all.

Another thing that bogs me down is the built in total advance of 46 degree.
I got two theories. First is the the rotor tip is wide that much and is a mechanical limit.
Second is the soft theory. The degrees between falling edge of the widest low res slot and the rising edge of the next low res slot is exactly 46 degrees, It could be coincidence, but as we know in the code PCM counts high res slot between falling edge and rising edge of low res signal and determines current firing cyl ID.
It is verified by data stream at RAW cyl ID and it is a perfect match.

What is strange there is built in +-2 degree error built in the code. The cyl ID on first cyl can vary between 44 and 48 degree. If it is outside this range high res failure code is triggered.
I have monitor the cyl id raw value and at rapid rpm changes the counts on cyl ID drops by 1 or 2 degrees.

I noticed that the northstar ign module uses a 4x cam sensor also. Could the delteq modify the low res signal and feeds it to the ICM.

Quote:

---

Originally Posted by kur4o

That scope is real fun to play with.
I still need some more info to decode the information.
Is the injector pulse the dip or the rise on the graph and what is measured volts or amperage.
That cylinder pressure thing is also very interesting. Can you gavi some info how it is measured and what tools are needed.

I used a Fluke PV350 Pressure/Vacuum Transducer Module, coupled to a air hose quick connect, coupled to a compression guage hose with the schrader valve removed. Linked with alligator clips to the annoying snap-on verus scope/scantool connectors. The dip in the injector voltage waveform is when the driver is turned on on the ground side of the injector.

Since the TPU controls injectors, the only way to tell injectors are in sequential mode is to monitor the coils with a scope.
Can you do that graph with varying rpm and tps, so we know exactly at what conditions batch mode is used and how PWM are calculated at batch mode if it exists at all.

I only have 4 channels on my scope, but when I was checking out the buick v6, I used a 10 bar led graph display with current limiting resistors to find out batch fire was only used during cranking unless the cam sensor signal was missing. I imagine the strategy did not change, but we don't know for sure. I will see what I can do. I think I can current ramp all the injectors at once at the power source, and see what I get.

Another thing that bogs me down is the built in total advance of 46 degree.
I got two theories. First is the the rotor tip is wide that much and is a mechanical limit.
Second is the soft theory. The degrees between falling edge of the widest low res slot and the rising edge of the next low res slot is exactly 46 degrees, It could be coincidence, but as we know in the code PCM counts high res slot between falling edge and rising edge of low res signal and determines current firing cyl ID.
It is verified by data stream at RAW cyl ID and it is a perfect match.

I like the mechanical limit theory, because it is related to longevity and the limit placed on a 10.25 compression ratio engine running regular gas. We will be able to exceed this when we go to the coil on plug setup.

What is strange there is built in +-2 degree error built in the code. The cyl ID on first cyl can vary between 44 and 48 degree. If it is outside this range high res failure code is triggered.

I believe this allows for timing chain slop and optispark bearings wearing out, so that you have a chance to make it somewhere before it quits completely. Fault tolerance and recognition.

I noticed that the northstar ign module uses a 4x cam sensor also. Could the delteq modify the low res signal and feeds it to the ICM.

---

I think the deltec module syncs to the LowRes signal, and uses the HiRes signal as a clock input to generate signals that are 1 degree accurate.
Oh crap. The injector waveform voltage is incorrect, as I left the input on the AC voltage setting. I reposted the waveform posting with some values.

By the way, there is an arduino ecm project. https://speeduino.com/wiki/index.php/Speeduino
For those who are interested.

Quote:

---

Originally Posted by vilefly

We should have a number of different choices person could try to see what works for them. Not sure what constitutes easy, but if the code is posted for the arduino version, it should make it a lot easier for someone to try. Mine is a hardware approach at it, since it is all I know. I need more free time to tinker with arduinos and raspberry pi's. I don't think I will be doing much coding, heh. But I will post my schematics, which aren't finished right now, just so I can remember where I left off.

---

Well like I said in my previous post, Im no expert, but I'm not a newbie either. If a schematic gets posted that should be enough.

I actually have an arduino that i don't use for anything currently, I have the IDE on my computer as well, and am somewhat familiar with coding.

Let me know if there is anything I can do to help you guys.

Ok kur4o,
here is quick screenshot I grabbed from playback mode. This event is during cranking/startup. Just like the 3800 engine, it starts with simaltaneous double-fire, then switches to sequential on the 3rd revolution. Basically, it pulses all injectors once per revolution, until the 3rd rev.
Attachment 12138
The current draw indicates how many injectors are firing.
I was carrying on conversations with 2 different people when I was doing this at the last 15 min of the day. So excuse the lack of other reference signals.

I am posting this just for easy reference, so we can find this all in one place. The Northstar ignition module wiring and the signal waveforms going in and out of it.
Attachment 12139
Attachment 12141
Hope this answers more questions than it creates. During startup, no 5v signal is sent to the BYPASS input until after 400rpm, where 5v makes the module switch to computer ignition control. From then on, the computer has direct control as to WHEN the next coil is going to fire. The module keeps track of WHICH one to fire.

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.

Quote:

---

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?

Found this site:
http://lukeskaff.com/projects/car/ca...c-ecm-project/

and a delteq diagram

Quote:

---

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?

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?

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