CA18DET Dwell values

[Nissanclubman]

Yesterday I decided to finally put to rest my old CA18DET coils. I am running the Std ECU they just don't do the job any more under boost. Spark gap is down to 0.5mm and even at that are blowing out.

I have converted to the LS2/Truck or Yukon coil and have ditch the CA igniter as well. Very simple convertion and am now firing the new coils direct from the ECU.

The LS2 truck coils have a massive increase in spark energy and to optimise the coil requires a longer dwell time.

Dwell is configured 3890 and the figures are below (digital).
The std dwell for the CA coils is 2 ms and I need to increase this to around 5 ms.

Does anyone know how to evaluate the std values to milli sec or calculate the change to the values to increase dwell to 5 ms?

Any throughts are welcome

10
10
15
21
28
35
40
47
53
60
67
74
79
85
92
99
106
112
119
126
133
139
146
153
159
166
173
180
186
193
200
207

[Zuikkis]

The std dwell for the CA coils is 2 ms and I need to increase this to around 5 ms.

Just multiply each value by 2.5* and it should be fine.

[skylinegtrhr]

Sorry for little off topic:

Would this LS coil pack combination work on S14 SR20DET ,
does anyone have experience as we have problem with old coils on our demo car...

[Nissanclubman]

Sorry for little off topic:

Would this LS coil pack combination work on S14 SR20DET ,
does anyone have experience as we have problem with old coils on our demo car...

The S14 DET ECU has Ingnitor outputs on pins 1, 2, 11 and 12 similar to the CA ecu. I can't see any reason why it won't work. Haven't tested it on an S14 however. Cheers

[Nissanclubman]

The std dwell for the CA coils is 2 ms and I need to increase this to around 5 ms.

Just multiply each value by 2.5* and it should be fine.

Thanks. However I don't know how I will go with some of the numbers. The table will only accept a value range up to FF (hex) or 255 (dec)

[Zuikkis]

The std dwell for the CA coils is 2 ms and I need to increase this to around 5 ms.

Just multiply each value by 2.5* and it should be fine.

Thanks. However I don't know how I will go with some of the numbers. The table will only accept a value range up to FF (hex) or 255 (dec)

Oh yeah, at high RPM it will get too big. I guess you could modify the voltage curve as well, or actually perhaps modify only that? The table has 255 at the beginning, but that's only for under 8 volts or so.. After 11 volts the values are well in range for you to multiply by 2.5.

[iceblade]

can we have some more info on this setup please....??? pretty please....
been tryin to work something out to replace standard ca18det coils for a while now but i dont have much time to research etc....

[Nissanclubman]

Thanks. However I don't know how I will go with some of the numbers. The table will only accept a value range up to FF (hex) or 255 (dec)[/quote]

Oh yeah, at high RPM it will get too big. I guess you could modify the voltage curve as well, or actually perhaps modify only that? The table has 255 at the beginning, but that's only for under 8 volts or so.. After 11 volts the values are well in range for you to multiply by 2.5.[/quote]

Yes you are right and what I was also suspecting. I tried it last night and not a single missfire with 15psi and plug gap at 1.1mm Here is my current settings.

Table modified was 3F00 16 bit, Dwell vs Coil Volts
Not sure what the scale is but I suspect it is from 8v during cranking to 15.5v max battery charge value.

Original settings.

255, 255, 255, 255, 255, 255, 255, 183, 134, 107, 89, 76, 67, 59, 54, 49

My new settings.

255, 255, 255, 255, 255, 255, 255, 250, 240, 230, 220, 180, 165, 145, 130, 125

I also changed the Dwell vs revs table 3890 lower numbers to improve idle.

Orignial

10, 10, 15, 21, 28, 35, 40 the rest un changed

My new settings

35, 35, 35, 35, 38, 39, 40, rest as original

Thanks for your help and if I find out more information I'll post it. Cheers Richard

[Nissanclubman]

can we have some more info on this setup please....??? pretty please....
been tryin to work something out to replace standard ca18det coils for a while now but i dont have much time to research etc....

The LS2 coils have internally built ignitors so only need a pulse (between 3-5v) to trigger them. The CA ECU has four pulse cables that go to the Ignitor then to the CA coils. The CA coils have three wires to them. 12v Ign, ECU pulse and ground.

The LS2 cois have 4 wires. 12v Ign, ECU pulse and two ground connections. One for the internal ignotor and the other for the Primary coil. I just joined them together and connected then to the Engine earth.

I used the original 12v Ign from the Ign relay and ran each of the Pulse cables from the ECU directly tot he new LS2 Pulse input terminal on the LS2 coil.

When I started it ran with out anut ECU programing changes however spark broke down at 7-8 PSi boost. Changed the Dwell settings as above and can now run to 15 PSI no problems..

Hope this helps. If you need photos or connection diagram I'm happy to modify the S13 Nissan circuit diagram showing the changes. Cheers for now. Richard

[Nissanclubman]

One of the other mods I have done to the ECU is to replicate the ECU fault circuitry to a diplay on the dash so I can set the fault mod on the fly and check any of the faults at any time.

One of the things I have noticed is a code 21 fault being reported. This is an ignition coil pulse error and has a number of potintial causes. I have checked this out and it is a false report by the ECU as a side affect of removing the Nissan Ignitor and conncecting the ECU signal directly to the built in ignitor in the LS2 coils.

Not sure if there is a fix for this, will look in to it further, but it definately isn't causing any loss of ECU output triggers, Coils triggers or spark miss firing. That's for sure.

For the moment I am happy to live with the error code as a side affect of the great result from the conversion.

Just as a final note. This doesn't affect any other faults being reported by the ECU. All that happens is the ECU toggles between the two errors. Reports one then the other etc.

[iceblade]

thanks for the info bud, really helpful....

[skylinegtrhr]

Hi does anybody who use LS2 coils expirience "discharge as a their form of overdwell protection" when dwell time is about 5ms?
This is topic with little more info:
http://efi101.com/forum/viewtopic.php?t ... c6d6930e38

we still don't use them so any experience is appreciated
Thanks in advance