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Need help understanding ignition module protocol 
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LQFP112 - Up with the play
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Location: Jersey City, USA
I am trying to understand the communication between my ECU and my ignition module. 96 Ford Aspire (kia/mazda) here - ignition coil is inside the distributor.

With a logic analyzer I see my CKP sensor sends four pulses per camshaft revolution and four pulses on the sparkout wire coming from the ECU. I am hoping to extract ignition advance data from the comparison of these two signals.

What could be the physical sense of the spark out signal? These signals are around 4ms wide. Is it the time needed to charge the coil, and the spark occurs on the level fall? This case the signal is CHARGE/FIRE. I hope it is not something like the Ford EDIS with it's 'advance pulse' protocol.

I've noticed that the pulse width is about 3.7ms in the 1500-5000 rpm range, but it is up to 7ms long for lower RPMs. If that would be just the charge/fire, what would be the reason for the pulse width variation?

Here is a chart of the sparkout pulse widths for different RPMs:
Image

Here is some data from my log, I will try to attach the log:
Code:
ckp start   ckp end      spout start   spout end   TP   rpm   CKP width   sparkout width
ms      ms         ms      ms      %   rpm
510489.61   510501.63      510496.83   510501.12   0   968   12.02   4.29
510520.58   510532.74      510527.79   510532.07   0   968   12.16   4.28
510551.82   510563.89      510559.17   510563.47   0   960   12.07   4.3
510740.65   510752.83      510747.84   510752.16   0   950   12.18   4.3199999999
511057.01   511069.27      511064.27   511068.59   0   949   12.26   4.32
511373.3   511385.44      511380.44   511384.75   0   956   12.14   4.31
511685.71   511697.85      511692.99   511697.29   0   960   12.14   4.3
511997.51   512009.63      512004.74   512009.03   0   964   12.12   4.29
512309.94   512322.15      512317.3   512321.62   0   952   12.21   4.32
512625.2   512637.48      512632.45   512636.78   0   945   12.28   4.33
....
689236.02   689239.5      689234.77   689238.27   0   3374   3.48   3.5
689325.29   689328.77      689324.03   689327.54   0   3351   3.48   3.51
689415.05   689418.56      689413.82   689417.32   0   3333   3.51   3.5
689505.68   689509.21      689504.45   689507.97   0   3296   3.5299999999   3.52
689596.9   689600.46      689595.7   689599.2   0   3282   3.5599999999   3.5
...
691201.52   691205.56      691200.59   691204.14   0   2887   4.04   3.55
691305.91   691309.98      691305.04   691308.54   0   2862   4.0699999999   3.5
691421.59   691425.7      691420.72   691424.24   0   2838   4.11   3.52
691527.7   691531.85      691526.87   691530.37   0   2819   4.15   3.5
691634.92   691639.11      691634.1   691637.63   0   2782   4.1899999999   3.53
691743.06   691747.28      691742.28   691745.77   0   2767   4.22   3.49
691852.3   691856.57      691851.53   691855.06   0   2732   4.2699999999   3.53
691962.6   691966.91      691961.89   691965.4   0   2712   4.3100000001   3.51
692073.97   692078.31      692073.26   692076.8   0   2683   4.3400000001   3.54
692186.24   692190.64      692185.58   692189.09   0   2661   4.4   3.51
692300   692304.44      692299.36   692302.89   0   2617   4.4399999999   3.53
692414.81   692419.28      692414.22   692417.71   0   2610   4.47   3.49
692530.64   692535.17      692530.05   692533.59   0   2572   4.53   3.5399999999
692647.91   692652.49      692647.37   692650.88   0   2551   4.58   3.51
692766.5   692771.13      692765.98   692769.51   0   2516   4.63   3.53
692886.51   692891.2      692886.05   692889.55   0   2489   4.6899999999   3.5
693007.9   693012.64      693007.43   693010.98   0   2459   4.74   3.5499999999
693130.7   693135.5      693130.29   693133.81   0   2433   4.8   3.52
693255.17   693260.03      693254.79   693258.33   0   2394   4.86   3.5399999999
693381.04   693385.97      693380.71   693384.23   0   2371   4.9299999999   3.52
693509.04   693514.05      693508.76   693512.29   0   2327   5.01   3.53
693638.8   693643.89      693638.57   693642.1   0   2297   5.09   3.53
693771.53   693776.74      693771.35   693774.91   0   2232   5.21   3.5600000001
693907.69   693913.05      693907.66   693911.18   0   2178   5.3600000001   3.52
694047.97   694053.51      694048.01   694051.59   0   2102   5.54   3.58
694192.92   694198.63      694193.11   694196.64   0   2047   5.71   3.53
694342.99   694348.93      694343.45   694346.89   0   1959   5.9400000001   3.4400000001
694499.06   694505.24      694499.82   694503.26   0   1892   6.1799999999   3.4400000001
694665.63   694672.61      694667.22   694670.66   0   1683   6.98   3.4400000001
694866.21   694875.08      694869.74   694873.49   0   1342   8.87   3.75
695136.95   695149.37      695144.36   695148.68   0   962   12.42   4.3200000001
695572.86   695593.39      695585.03   695590.97   0   571   20.53   5.9399999999
696066.16   696083.86      696076.84   696082.05   0   654   17.7   5.2100000001
696412.18   696420.68      696415.65   696419.33   9   1312   8.5   3.6799999999
696606.68   696613.65      696609.87   696613.34   14   1665   6.97   3.47
696782.78   696789.59      696785.8   696789.25   15   1717   6.8099999999   3.45
696972.28   696980.98      696977.16   696981.25   20   1370   8.7   4.09
697169.78   697176.69      697173.28   697176.79   60   1701   6.9099999999   3.51
697360.36   697367.38      697363.83   697367.57   91   1629   7.02   3.74
697530.21   697536.77      697533.23   697536.67   100   1795   6.5600000001   3.4400000001
697699.88   697706.14      697702.79   697706.23   100   1842   6.26   3.4399999999
697855.97   697862.06      697858.46   697861.91   100   1921   6.0900000001   3.4500000001
698009.25   698014.97      698011.39   698014.84   100   2021   5.72   3.45
698152.55   698158.11      698154.38   698157.89   100   2108   5.5599999999   3.51
698293.84   698299.18      698295.5   698299.01   100   2177   5.3400000001   3.51
698427.39   698432.54      698428.76   698432.27   100   2272   5.15   3.51
698558.78   698563.78      698560.03   698563.54   100   2327   5   3.51
698684.2   698689      698685.21   698688.72   100   2429   4.8   3.51
698806.5   698811.19      698807.43   698810.94   100   2471   4.6899999999   3.5099999999
698925.25   698929.81      698926.01   698929.52   100   2564   4.5600000001   3.51
699041.04   699045.48      699041.68   699045.19   100   2620   4.4399999999   3.5099999999
699153.69   699158      699154.17   699157.68   100   2700   4.3100000001   3.51
699263.51   699267.75      699263.75   699267.37   100   2762   4.24   3.62
699370.83   699374.96      699370.97   699374.57   100   2830   4.13   3.6
699527.33   699531.32      699527.42   699530.91   100   2932   3.99   3.49
699628.76   699632.7      699628.72   699632.28   100   2976   3.9399999999   3.5600000001
699728.85   699732.7      699728.77   699732.28   100   3030   3.85   3.51
699826.4   699830.16      699826.17   699829.74   100   3105   3.76   3.5699999999
699921.91   699925.61      699921.65   699925.17   100   3171   3.7   3.52
700015.91   700019.54      700015.49   700019.13   100   3205   3.63   3.64
700108.26   700111.85      700107.79   700111.39   100   3278   3.59   3.6
700199.17   700202.69      700198.62   700202.27   100   3329   3.5199999999   3.65
700288.75   700292.18      700288.12   700291.77   100   3378   3.4300000001   3.65
700376.58   700379.95      700375.92   700379.53   100   3452   3.37   3.61
700463.17   700466.53      700462.51   700466.09   100   3488   3.36   3.58
700548.67   700551.98      700547.94   700551.55   100   3537   3.3099999999   3.6100000001
700632.69   700635.92      700631.84   700635.49   100   3605   3.2300000001   3.65
700715.42   700718.6      700714.57   700718.19   100   3636   3.1799999999   3.62
700829.7   700832.81      700828.8   700832.4   100   3717   3.1100000001   3.6
700925.47   700928.51      700924.51   700928.1   100   3797   3.04   3.59
701004.31   701007.32      701003.27   701006.9   100   3807   3.0099999999   3.63
701082.35   701085.32      701081.3   701084.91   100   3875   2.97   3.61
701166.92   701169.85      701165.75   701169.45   100   3921   2.9299999999   3.7
701242.85   701245.8      701241.65   701245.33   100   3968   2.9500000001   3.6799999999
701318.04   701320.91      701316.76   701320.5   100   4005   2.87   3.74
....
969591.17   969597.29      969591.72   969595.17   0   1913   6.12   3.4500000001
969757.72   969764.57      969759.23   969762.68   0   1709   6.85   3.4500000001
969949.97   969958.13      969952.76   969956.41   0   1440   8.16   3.65
970182.24   970192.62      970187.4   970191.41   0   1148   10.38   4.01
970503.08   970518.59      970512.68   970517.44   0   773   15.51   4.7599999999
971030.16   971054.7      971045.37   971052.2   0   479   24.5399999999   6.83
971615.23   971635.34      971627.39   971633.47   0   570   20.11   6.08
972102.89   972121.02      972113.7   972119.06   0   636   18.13   5.3600000001
972555.23   972572.24      972565.24   972570.34   0   680   17.01   5.1
972978.54   972994.42      972988.08   972992.99   0   727   15.88   4.91
973382.53   973398.02      973392.12   973396.97   0   749   15.49   4.85
973777.9   973793.12      973787.53   973792.33   0   761   15.22   4.7999999999
974180.79   974196.79      974190.51   974195.49   0   727   16   4.98
974589.23   974604.87      974598.8   974603.68   0   740   15.64   4.88
974994.95   975010.71      975004.56   975009.51   0   738   15.76   4.95
975399.86   975415.45      975409.61   975414.47   0   744   15.59   4.86
975801.19   975816.75      975810.98   975815.83   0   747   15.5600000001   4.85
976204.41   976220.06      976214   976218.94   0   740   15.65   4.9399999999
976607.51   976623.14      976617.17   976622.03   0   744   15.63   4.86
977013.72   977029.51      977023.33   977028.23   0   733   15.79   4.9


Attachments:
File comment: both signals in logic analyzer
spark_out2.png
spark_out2.png [ 54.93 KiB | Viewed 3543 times ]
File comment: both signals in logic analyzer
spark_out.png
spark_out.png [ 52.09 KiB | Viewed 3543 times ]
[The extension csv has been deactivated and can no longer be displayed.]

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Sun Mar 10, 2013 5:31 am
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Really cool data! :-)

The curve is of the dwell time. It's not like EDIS at all. The dwell is the coil charging up, and when the dwell ends, the spark (maybe) jumps.

The two things you're seeing there other than the constant 3.7ms section (optimal saturation time with the hardware involved under normal running conditions) are these:

At higher RPM there simply isn't time to dwell for 3.7ms and fire a spark properly for 1 or 2 ms after that, for four cylinders, from one coil. See here: viewtopic.php?f=24&t=48

Mind if I add your chart to that thread?

At lower RPM, below 500 or so your alternator isn't charging much and the voltage has fallen. Lower voltage = longer dwell required for saturation. Below 300 or so, you're still cranking, so voltage is very low due to starter load. Same applies.

Fred.

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Sun Mar 10, 2013 10:50 am
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Fred, the chart is totally yours!

Thanks for the clarification, I'll go see if I can figure out ignition advance logic based on the fact that the sparkout level fall is my spark moment.

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Sun Mar 10, 2013 4:52 pm
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Thanks! I opened up your CSV, which columns represent the dwell? Hoping to do a new curve with smaller dots to better show the relative density.

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Sun Mar 10, 2013 5:10 pm
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LQFP112 - Up with the play
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Ops, that raw file did not have the dwell column - dwell is fourth column minus third column
A processed file with the dwell column should be attached here.


Attachments:
[The extension csv has been deactivated and can no longer be displayed.]

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Sun Mar 10, 2013 5:22 pm
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Thanks! :-)

Image

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Sun Mar 10, 2013 7:00 pm
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