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Old 06-10-2016, 03:06 AM   #1
ZVOLV
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Default Analysis of EZK ignition system.

Crank sensor is a Variable Reluctance Sensor and it sends a signal to the EZK ignition computer:




The EZK ignition computer sends a 5v square wave to the ignition power stage to control dwell and timing:



The powerstage grounds the ignition coil. Primary voltage can exceed 400 volts!:



Then after that, Secondary Ignition occurs!!! This is a trace of Secondary Ignition Voltage (Kilovolts) along with Primary Ignition Current (Amps):

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Old 06-13-2016, 07:47 PM   #2
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Good stuff.
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Old 06-13-2016, 09:24 PM   #3
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What data does it use to calculate the ignition advance?
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Old 06-13-2016, 09:51 PM   #4
Karl Buchka
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Quote:
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What data does it use to calculate the ignition advance?
The EZK receives a load signal from the fuel computer. That, along with RPM, coolant temp, and the knock sensor input, is used to control timing.
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Old 06-13-2016, 11:26 PM   #5
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Quote:
Originally Posted by Karl Buchka View Post
The EZK receives a load signal from the fuel computer. That, along with RPM, coolant temp, and the knock sensor input, is used to control timing.
Ah, the eighties. A separate computer each for spark and fuel.

The weird dual coolant temp sensor is a neat artifact of that
scheme.

The fuel computer gets RPM data from the EZK, correct?

Maybe Zach will have a chance to stick his oscilloscope on the
load signal between the computers. I bet that would be
interesting. I'm going to guess it's a 5v PWM square wave.
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Old 06-14-2016, 01:18 AM   #6
Karl Buchka
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It's been a few years since I looked at the traces. If I remember correctly, the EZK sends a 50% duty square wave to the fuel computer with the rising edge denoting an ignition event and the fuel computer sends a variable duty, fixed frequency wave back to the EZK to indicate load.
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Old 06-14-2016, 11:16 AM   #7
ZVOLV
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Quote:
Originally Posted by sim View Post

The fuel computer gets RPM data from the EZK, correct?
Yes. I think it's just a square wave that increases frequency with RPM. I forget. I have researched it before. Gotta redo my work.

Quote:
Originally Posted by sim View Post


Maybe Zach will have a chance to stick his oscilloscope on the
load signal between the computers. I bet that would be
interesting. I'm going to guess it's a 5v PWM square wave.
There are THREE wires that connect EZK and LH box.

1: RPM signal FROM EZK box to LH box. The crank sensor signal goes direct to EZK box. It converts it likely to a square wave that gets sent over to LH box.

2. KNOCK signal FROM EZK box to LH box. This one I think is just an increasing voltage. Again, I lost my data. Please help me out.

3. Third wire. LOAD signal from LH box to EZK box.

SEEEE!?: Pins 17, 8, and 4 on the EZK go to 1, 25, and 28 on the LH box. Help me remember what they are and do. I gotta hit IPDdowns? website again. He broke it down, but it was kinda hard to understand and needed more info.

Here it is:

http://ipdown.net/wiki/index.php/EZK#Knock_control


I guess I could slap the old high end scopometer to each of these three wires on my time off and see what they look like with a modern scope. The publications are decades old and assume a tech has just a crappy multimeter. Technology is better now and so I go by waveform analysis instead of some obscure voltage reading on a 30 year old chart!


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