Need help understanding ignition module protocol

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russian
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Need help understanding ignition module protocol

Post by russian »

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: Select all

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
both signals in logic analyzer
both signals in logic analyzer
both signals in logic analyzer
both signals in logic analyzer

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

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Fred
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Re: Need help understanding ignition module protocol

Post by Fred »

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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russian
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Re: Need help understanding ignition module protocol

Post by russian »

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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Fred
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Re: Need help understanding ignition module protocol

Post by Fred »

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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russian
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Re: Need help understanding ignition module protocol

Post by russian »

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.
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Re: Need help understanding ignition module protocol

Post by Fred »

Thanks! :-)

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