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Old 03-01-2015, 09:18 PM   #1
turbotankshane
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Default ls2 d585 coils on ez116k wasted spark

Have some of these heatsinked coils I got set up yesterday, they've been running without issue, but I've been wondering if stock dwell is too much for them... I've been reading that people are usually running them from 4-5ms and that much more than that can be dangerous, as built-in overdwell protection will cause them to fire early and cause a dangerously advanced spark. Last time I measured dwell at idle on the stock bosch module and coil, it was around 6.5-7ms. Should I be adjusting this down to around 4?
Who's been running them here, and have you had any issues with them or ls coils in general?

Also, seems my launch control arm circuit is stuck around 2k rpm... anyone else have an issue like this with the Buchka wasted spark board?
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Old 03-01-2015, 11:14 PM   #2
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Factory GM applications adjusts dwell based on voltage and engine speed. At 13 volts they run anywhere between 4.5ms to 3.5ms from low to high RPM. If you're running wasted spark 3.8-4ms @ 13v should be sufficient.
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Old 03-02-2015, 12:40 AM   #3
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The wasted spark board doesn't adjust dwell. It just multiplexes the stock spark output to two channels. Unless you can reflash the EEPROM in the EZK to change the dwell, you're stuck at whatever it outputs, which (as you said) is around 6.5ms. I don't know how the LS coils react to that kind of dwell.

What color is your circuit board? Are you sure you've wired the Set switch properly from the board? When you do press the set button, do you get a momentary flutter in the engine RPM?
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Old 03-02-2015, 12:56 AM   #4
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Ipdown had put together a program that would modify the dwell tables to 2.5ms for VAG coils, and when I was trying to use those, I built another small board to take the signals from your board and use them to trigger two PNP transistors to invert the signal to drive them and used his program. However with his dwell tables I came out to about 4ms dwell measured on the car with a scope. I was able to use an ostrich and the tables his program modified to get the dwell down to around 2.5ms with those, so I'm currently using the original dwell tables his program patched in until I can use the scope again.
With the dwell down at around 4ms it's running much smoother and pulls harder in boost.

The board I have came from another forum member, and it's one of the older black ones; the 1-4 and 2-3 outputs are backwards, had to switch them to make the car run. When I first got it all set up with these coils and wired up the set and arm switches I verified they were working by arming it without setting an elevated RPM. This killed the car so I knew that circuit was good. I then hit the set switch at 2000 rpm to test that circuit. It worked the first time but ever since then I can't reset it and its stuck at 2000 rpm, even after a universal reset. I do get a flutter in engine speed when I hit the set switch.
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Old 03-02-2015, 01:04 AM   #5
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I guess it could be useful knowledge that the set circuit is run through the load side of a four pin automitive relay with control side being fed 12v through the a/c switch then through pins 85 and 86 to ground.
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Old 03-02-2015, 01:32 AM   #6
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I'm not quite sure I follow how you've wired it. Can you draw it out?
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Old 03-02-2015, 08:41 PM   #7
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Oops, I falsified information. I have the arm switch set up that way, the set switch is just an interruptor, no relay.
It's like this



Except the a/c switch is the arm switch.. you get the idea.

I only set it up on a relay because I was trying to use a touch-sensitive switch for cool points, and it had to have a 12v feed, so I didn't think it would work on a 5v circuit. But then both of those touch switches I had turned out to be junk so I just set it up on the a/c switch since my a/c is deleted anyways

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Old 05-02-2015, 09:55 PM   #8
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Quote:
Originally Posted by turbotankshane View Post
[LS2 coils]...running them from 4-5ms [@ 14 volts]..I measured dwell at idle on the stock bosch module and coil, it was around 6.5-7ms....
There are time duration differences in coil-dwell timing that depend upon the coil's properties.

Cylinders - As noted at MegaSquirt,, "...for a V8 at 600 rpm, the time between sparks is 25 milliseconds. At 6000 rpm the time is just 2.5 milliseconds. "

Primary Side of Coil >>> 12 Volt Voltage-Time-Duration - Most coils are designed to operate in 2.0 to 6.0 milliseconds range. So, one coil might tolerate 2 ms @ 14-volt, and another coil 4 ms @ 14-volt.



Sources:

MegaSquirt - Dwell Setting

Understanding, Testing and Calibration of Ignition Coil Dwell Time

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Old 05-03-2015, 02:12 PM   #9
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Quote:
Originally Posted by turbotankshane View Post
I've been wondering if stock dwell is too much for them...
Just the opposite...its Good!

"They contain all the electronics for dwell limiting, current limiting, etc. ....

When the signal from the sequencer is high (3 to 5+ Volts - with very little current from the controller, a few dozen milliAmps), the coil current will be building. When the signal from the sequencer is pulled low (shut off), the coil will spark. The duration of the signal from the sequencer determines the dwell (though the coil igniter limits this to no more than ~8 milliseconds).

As the dwell time increases, the peak coil charge current increases. The coil output current is not as linear. The LS1 coils do not fully saturate until around 8 milliseconds, but the spark energy does not increase much when the dwell exceeds 6 milliseconds.



So stick with a 'running' dwell setting near the design value of 5.6 to 5.8 milliseconds. This will keep the coils cooler and extend their life.





Question - What type of signal does EZ116K send to ignition module???? Could ignition module be removed, and just send EZ116K's signal directly to this LS2 coil?
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Old 05-03-2015, 03:35 PM   #10
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Quote:
Originally Posted by 84B23F View Post
Question - What type of signal does EZ116K send to ignition module???? Could ignition module be removed, and just send EZ116K's signal directly to this LS2 coil?
Karl would be better suited to answer than I, but IIRC, the spark output signal circuit is pulled low by the EZK. Karl's wasted spark board simply splits that signal between two circuits. So now, there is a 1-4 coil circuit that is pulled low when current is to start building for those two coils, and a 2-3 coil circuit that operates in identical fashion for the other two coils.

So to answer your question, that's how this particular ignition setup operates.
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Old 05-03-2015, 05:38 PM   #11
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Quote:
Originally Posted by turbotankshane View Post
Karl's wasted spark board simply splits that signal between two circuits.
A single D585 maybe a good mod for single coil setup, if EZ116K's trigger signal is OK.

I've not explored Rex-I's trigger signal.

One might bump spark gap an extra 0.010" and get a pinch better fuel economy and performance on NAs.

That aftermarket D585 has 35,000 volts. Of course, one might use 8 mm wires.

I did come across this forum's thread: LS2 truck coils, over dwell, and spark "scatter",

If a single D585 was setup on NA, one could evaluate this potential issue.

I've got a MAC Tool Automotive Multimeter, I may look at coil's dwell time.

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Old 05-03-2015, 09:27 PM   #12
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Quote:
Originally Posted by turbotankshane View Post
stock bosch module and coil, it was around 6.5-7ms.
I tested LH 2.4 NA @ 79°F(26°C) outdoor temperature with engine up to temperature...

from idle to high RPM....just less than 6 ms to 3.5 ms...coil dwell decreases from idle to high RPM. Just a pinch above idle, its in the 5 ms range.

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Old 05-03-2015, 10:52 PM   #13
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40% Duty Cycle - Several forums have suggested a maximum of 40% duty time, so with a LS2 Wasted Spark [Volvo] with 4 ms dwell @ 6,000 RPM, this would represent 40% duty. With a Single LS2 Coil Setup @ 4 ms dwell, this would be reached at 3,000 RPM; so with a single coil, exceeding 3,000 RPM would create an issue. But stock NA might have lower dwell at 3K revs...have to test.

Startup Dwell - Something that needs to be evaluated. One of those aftermarket controllers increase dwell greatly at startup. As noted there,

Smart coils handle over dwell in 2 different ways that i have seen.

1. When the coil goes into overcharge it fires the coil to protect itself. This early spark event does the engine no favors. LS2 truck coils (D585) handle overdwell this way. Not sure about the LS2 "car" coils yet. They might not be "smart coils."

Too much "voodo" information on various forums....it would be nice to have GM's tech sheet.
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Old 05-03-2015, 11:36 PM   #14
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PDF - Application Note GM, LSX, Coil Near Plug Ignition Coil - Notice the coil charge time as a function of voltage.

The D585 might be a coil to stay away from, if your dwell settings are not programmed correctly. "They will fire as soon as you hit 8A or so, without the ECM telling them to fire."

For coil charge time, the LS2 takes 4ms at 14 volts, and the LS9 takes 2.6 ms at 14 volts.

LS1s dwell are controlled via ECU.
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Old 05-05-2015, 12:44 AM   #15
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Quote:
Originally Posted by turbotankshane View Post
Have some of these heatsinked coils I got set up yesterday, they've been running without issue...
After scanning the available literature, here is my current assessment.

Using Pertronicix's literature

LS1/LS6 # D580 -GM # 12558948- 30,000 Volts
LS2/LS3/LS7 # D514A GM # 12573190 - 32,000 Volts
LS Truck # D585 GM # 10457730, 12563293 - 35,000 Volts

Forum Post: Volvo's Bosch Coil - 32,000 Volts???, but unknown charge/dwell time.

Coil Charge Time:

LS2 takes 4ms at 14 volts,
LS9 takes 2.6 ms at 14 volts.

ROLLOFF - No matter whether you have a points ignition or an electronic ignition, both are inductive, and all inductive ignition systems are sensitive to what is called roll off. Somewhere between 3000 and 3500 RPM, the input current to the primary begins to drop off because the recharge time is insufficient.

Opinion - As based upon above, I would drop back to D514A coils with a wasted spark setup when LH 2.4 is driving coil's dwell-time. Using a board with a fixed dwell of 4-ms coil charge time with wasted spark setup, the LS9 coil at 2.6 ms charge time might work.

On a different note for wasted spark setup, GM produced ACDelco D576 and D555 for use in four cylinders and on their V6 engines. Tech Info...User Experience These coils are capable of 35,000 and upwards to 40,000 volts, but two ignition modules would have to be used. That said, knowing these coils dwell time to full charge would be relevant to know. This coil dwell time topic needs to be explored on these coils; asking the GM tech department for spec sheet may be the only way to know for sure. I know a performance tuner in another forum, and I will attempt to find out.

Caution Note - For a wasted spark setup, it would be better to let LH 2.4 drive the coils via two ignition modules. If a board fixed the coil's dwell time at 4-ms, then the timing pooch would be screwed. If a board allows 4-ms maximum timing, but allows ECU's coil dwell time to be processed when under 4 ms, then at higher Rpm, this board would work OK.

An EFI system sets the needed timing advance when it stops the coil charge time; when coil is no longer being charged, the coil's high-voltage output spark is being sent to distributor cap. Hence, the ECU's end of coil-dwell-time must be the trigger to allow the coil to discharge. Otherwise, the timing pooch is SCREWED

10. At 900 rpm it takes 4.629 milliseconds for the crank to travel the 25 degrees from 10 degrees before TDC to 15 degrees after TDC. At 6,000 rpm this movement takes just 0.694 milliseconds. Remembering that the flame front has a constant burn rate then to have the flame front and piston converge when the piston is just after TDC requires the combustion process to start earlier in the cycle at higher rpm. Otherwise the piston would be lower down in its location before the flame front reached it.
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Old 05-05-2015, 01:51 AM   #16
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Quote:
Originally Posted by turbotankshane View Post
With the dwell down at around 4ms
Very Important Point - An EFI system sets the needed timing advance when it stops the coil charge time; when coil is no longer being charged, the coil's high-voltage output spark is being sent to distributor cap. Hence, the ECU's end of coil-dwell-time must be the trigger to allow the coil to discharge. Otherwise, the timing pooch is SCREWED
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Old 05-05-2015, 07:45 AM   #17
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Quote:
Originally Posted by turbotankshane View Post
take the signals from your board and use them.
I'm going out of town today, but there is a safe way to use these truck coils.

On the OEM table, you will notice voltage vs dwell time; as voltage drops, more dwell time is needed.

Using a truck D585 coil dwell table vs voltage, I would find what voltage is required for say 6-ms coil charge time. Then using a resistor on power line to D585 coil to match this lower voltage required.

Hence, switch voltage going to the coil, and this might be done electronically, or with a switch.
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Old 05-05-2015, 08:33 AM   #18
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I'm running d514a ls2 coils in wasted spark, through a microsquirt. I am around 4ms dwell running. I was on the d585's initially but shied away after reading about the overcharge issues. I know I could have controlled for it, but the 514s have plenty of juice so why even introduce the risk.
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Old 05-05-2015, 10:34 AM   #19
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Quote:
Originally Posted by 84B23F View Post
Too much "voodo" information on various forums....
Heh, that's funny.
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Old 05-05-2015, 10:58 PM   #20
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Quote:
Originally Posted by Stiggy Pop View Post
...wasted spark, through a microsquirt..
In this forum post cited before, I omitted this tidbit:

2. When the coil goes into overcharge the stored energy is dissipated without firing the coil. This keeps the engine happy but no spark. Newer VAG (VW / Audi) coils handle overdwell this way.

I have not researched these coils, but a dwell table or fixed dwell must be used.

In this PDF, are what today's state of the art Delphi coils can do.

See: Primary Charge Time (14 V) on top of page five; the values range from 2.0 ms to 3.4 ms
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Old 05-05-2015, 11:09 PM   #21
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Quote:
Originally Posted by sim View Post
Heh, that's funny.
If you read this article, Improve Your Quarter-Mile Times Through Ignition Coil Selection, and this article, Understanding, Testing and Calibration of Ignition Coil Dwell Time, then one will find those Voodo solutions.
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Old 05-06-2015, 12:22 AM   #22
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Quote:
Originally Posted by turbotankshane View Post
coil, it was around 6.5-7ms.
FWIW, I did a full charge dwell time at MS's site, for a 40,000 volt Flame Thrower canister coil, like a Bosch Coil, at 5.8 amp draw, and it takes 5.51 ms to charge this coil fully.

If I get the time, I may check to see how many amps a stock Bosch coil draws.
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Old 05-06-2015, 01:23 AM   #23
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Quote:
Originally Posted by 84B23F View Post
If you read this article, Improve Your Quarter-Mile Times Through Ignition Coil Selection, and this article, Understanding, Testing and Calibration of Ignition Coil Dwell Time, then one will find those Voodo solutions.

Sorry, I meant that it is ironic to see comments about "Voodo"
information found on the internet, in a forum thread dominated with
speculative posts full of second-hand information about a system
that the poster seems to have no actual experience with.

It's funny.
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Old 05-06-2015, 02:35 AM   #24
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Quote:
Originally Posted by sim View Post
forum thread dominated with speculative posts full of second-hand information
Problem is in general is that OEMs don't release their tech tidbits.

I can't even find the specs for a stock 240 Bosch coil, although those who make aftermarket coils would know.

I've never explored this coil dwell time concept until this thread. Currently, I feel I have a decent grasp on this topic, but my reasoning got twisted along this path until I could sort the chaff from the wheat. Finding good tech overviews assists greatly, but these articles are few, and many folks can't read/understand the details; but once these are read, then a person can "re-evaluate" and put the puzzle together.

People bad mouth the D585 coil, but had they known about this coil's dwell time concept, they would not have screwed the pooch. Few people have a foothold on dwell time.

If high spark energy is required, the only solution is MSD type systems, which the track/drag folks use.

If one converted to a LS1/LS2 (not LS9), if the coil broke, a replacement would be easy to obtain, and cheap at JY. With Bosch ignition module and coil, if an auto supply has it in stock, they will stick it to you, but most likely, people living in rural areas will have to wait. But, I would like to know the GM facts, and if GM has revised the original coils; slim chance of finding this out, except on maybe a forum or two, where GM reps are around.
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