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Thread: DIY LTCC or similar system for LT1s

  1. #61
    Fuel Injected! vilefly's Avatar
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    Thanks dzidaV8, I figured that if I make it hardware based, anyone with a processor can make use of it.
    yup, heat kills the optical pickup by increasing the resistance of the led emitter until it burns out or is too dim to work. Heat kills hall effect sensors, too. Roughly at the same temperatures, too. It's just the fact that the emitter generates heat in operation is why it probably fails slightly sooner.

    I don't think the vortec timing cover fits the LT-1 due to the water pump/distributor drives. I think you mean the 1996-up timing cover that has the extra 4x reluctor and crank sensor. The tooth density that you speak of definitely would raise issues with the stock crank sensor. They are magnetorestrictive in nature, and can be quite touchy.
    A custom hi-impedence sensor would work better....something that develops a higher voltage per tooth, basically.
    Last edited by vilefly; 09-16-2017 at 04:54 PM.

  2. #62
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by dzidaV8 View Post
    It seems that over time temperature causes the LED and phototransistor to lost alignment somehow.
    I believe what happens is the phototransistor slew rate slows to the point it basically runs into saturation (on all the time) when it gets hot. Theres an "equivalent" sensor that was used by Chrysler in a traditional distributor application that was used heavily in cheap aftermarket optis that did this. The Chrysler application was designed to work in a thermosplastic distributor body, and wasn't able to handle the heat of operating while attached to an aluminum plate bolted to the front of the engine block.
    '95 C4 LT-1 ZF-6, Polo Green
    Comp 467 / XFI 280, UltraProMag RRs, LE1 Heads, Lunati 73925 Springs

    Somebody stole the spark plugs out of my other car, yet it still runs???

  3. #63
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    You need to use the 96-97 cover. The crank damper mount is also shorter to accommodate the trigger wheel.

  4. #64
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    I took the delteq apart and heres some pictures
    20170917_213504.jpg 20170917_213527.jpg

  5. #65
    Fuel Injected! vilefly's Avatar
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    Ah-ha! they used an UV eprom to possibly sequence the coils, which is something I considered as a cheat if I couldn't find the right combination of counters and gates. Could also simultaneosly store an advance curve, too. Can you read the number on the SOIC chip up there? I suspect a data distributor chip of some kind.
    He said it uses a northstar engine ignition module, but I have a doubt, since the northstar uses 2 crank sensors angled 27 degrees apart and a very complex reluctor wheel on the crankshaft.
    northstar.gif northstar2.gif
    Last edited by vilefly; 09-17-2017 at 07:56 PM.

  6. #66
    Fuel Injected! vilefly's Avatar
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    Still trying to work despite constant distractions. Here is roughly where I said I was at. The Digikey website has a free online electronics drafting program linked to their huge catalog. It is called "Scheme-it". Allowed me to post a diagram with a screen capture.
    ltcc.jpg

    I haven't setup the reset for the counter, and other stuff. but it should give everyone an idea.

  7. #67
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    The Delteq does use a Northstar module and coils.

  8. #68
    Fuel Injected! vilefly's Avatar
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    Quote Originally Posted by Tom B. View Post
    The Delteq does use a Northstar module and coils.
    Then this information will be useful to you. It is northstar ignition system trigger wheel at the exact size and configuration for 10* btdc base timing.
    https://www.thirdgen.org/forums/atta...thstar-dim.pdf


    this is the northstar ignition system patent.

    https://www.thirdgen.org/forums/atta...dis_patent.pdf

    so, I think I was right in thinking they used an eprom as a custom signal generator that is synched and clocked to the optispark signal.
    Easiest way I can think of to produce a complex waveform cheaply.
    Last edited by vilefly; 09-17-2017 at 09:36 PM.

  9. #69
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    Soic chip says HCF4050 31A317

  10. #70
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    Quote Originally Posted by vilefly View Post
    so, I think I was right in thinking they used an eprom as a custom signal generator that is synched and clocked to the optispark signal.
    Easiest way I can think of to produce a complex waveform cheaply.
    So does that mean we need to figure out what is on that eprom? I would almost rather use the LT1 ignition module and then use LS coils. I believe that is what your original plan was, right?

  11. #71
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    Found this pic of the LTCC that uses the LS coils

    LTCC1.jpg

  12. #72
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    More relavent reading. LT1 equipped boats used the Northstar ignition system

    http://www.ls1lt1.com/forum/lt1-%7C-...ar-lt-1-a.html

  13. #73
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    I've been trying to figure out what you're describing. The 1-8 demultiplexer made no sense. A 5-bit ripple counter could work by counting the high res pulses each time the low res turns-on.

    I assume once you have the count you'll latch it into a chip so it's held until the next count? You need to use a latch signal for this chip that transitions properly when the low res signal goes away.

    I would have expected you to use the high res as the clock to the ripple counter. I suppose you could and the high res and low res so the clock pulses only occur when both exist. Definitely use the low res as the input. So, the counter begins counting up during the low res pulse and then when the low res pulse ends you latch the count into the latch chip.

    I'm curious how you'll determine between the other 4 cylinders which have the equal 2 high res pulses. I suppose you could keep the count from the previous cylinder and then count the 2 pulse pattern on-top. Cylinder 4 would be 9 counts for example which is a unique count. This means you'd need a counter reset circuit that looked specifically for a 2-pulse pattern to reset the counter.

    I'm not sure why you'd want to use the ignition module and then use it to drive another ignition transistor. If you use LS coils you drive them at logic levels since they have a built-in driver.

    Best I can tell, the low res signal starts when the corresponding cylinder is at TDC. So, don't forget that you have to switch to the #8 cylinder when you've found the #1 TDC low res pulse so that the PCM can fire the #8 cylinder in advance of the #8 TDC low res signal appearing.

  14. #74
    Fuel Injected! vilefly's Avatar
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    Quote Originally Posted by Aroberson77 View Post
    So does that mean we need to figure out what is on that eprom? I would almost rather use the LT1 ignition module and then use LS coils. I believe that is what your original plan was, right?
    we might need to in order to prove/disprove any theories. I have no intention of using the original ignition module. The ignition transistors only cost about $1.29 each last time I checked. Allows me to use any coil configuration I want. I am still undecided which coil setup I want, because I have been wrong before. I am only mildly curious as to what is on the eprom, so don't do it for me, do it only if you want to. It is still possible to figure out what they did without an eprom's data.

  15. #75
    Fuel Injected! vilefly's Avatar
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    Quote Originally Posted by lionelhutz View Post
    I've been trying to figure out what you're describing. The 1-8 demultiplexer made no sense. A 5-bit ripple counter could work by counting the high res pulses each time the low res turns-on.

    I assume once you have the count you'll latch it into a chip so it's held until the next count? You need to use a latch signal for this chip that transitions properly when the low res signal goes away.

    I would have expected you to use the high res as the clock to the ripple counter. I suppose you could and the high res and low res so the clock pulses only occur when both exist. Definitely use the low res as the input. So, the counter begins counting up during the low res pulse and then when the low res pulse ends you latch the count into the latch chip.

    I'm curious how you'll determine between the other 4 cylinders which have the equal 2 high res pulses. I suppose you could keep the count from the previous cylinder and then count the 2 pulse pattern on-top. Cylinder 4 would be 9 counts for example which is a unique count. This means you'd need a counter reset circuit that looked specifically for a 2-pulse pattern to reset the counter.

    I'm not sure why you'd want to use the ignition module and then use it to drive another ignition transistor. If you use LS coils you drive them at logic levels since they have a built-in driver.

    Best I can tell, the low res signal starts when the corresponding cylinder is at TDC. So, don't forget that you have to switch to the #8 cylinder when you've found the #1 TDC low res pulse so that the PCM can fire the #8 cylinder in advance of the #8 TDC low res signal appearing.
    1) A 5-bit counter is not available in the marketplace. you have to build it out of flip-flops, and I will never give up precious breadboard space making that which is much easier to do with discrete components. 2 unused pins won't kill you, heh. The demultiplexer is not pictured yet.
    2) The nor gate does this already. I even wrote a note about its output.
    3) The AND gate turns excessive and fruitless work into a signal I can sync with. Again, this is already done. Who wants to count to 720?
    4) The circuit so far is merely for syncing during start. The rest of the time it will be the job of another counter that recycles automatically, coupled to the 1-16 demultiplexer/data selector, because they count 0, and the ripple counter does not. It will clock on the LEADING edge of the low-res optispark signal. (switch to next coil when TDC is reached)
    5) I never said I was going to use the oem ignition module. I have 8 transistors at my disposal.
    6) I already posted about advancing to the next coil in advance. The optical wheel I posted now has TWO sets of numbers on it.

    I don't believe in measuring and calculating on the fly. This leaves you vulnerable to a glitchy signal, and is not very fault tolerant. I am no longer an idealist. Just set the counter, and go.

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