DIY LTCC or similar system for LT1s

**vilefly** · 09-30-2017

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.