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2G Which is the correct way to wire COP w/ CDI

punk3rz

Supporting Member
209
69
Jun 1, 2012
Surgoinsville, Tennessee
Greetings all,
After searching and searching and multiple failed attempts for help on Facebook pages, I’m looking for advice on my COP wiring with CDI.
Parallel vs series-
I ordered a cop kit and it is wired like this:
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While all the threads I’m finding show to wire them like this:
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I contacted the manufacturer to let them know what I’ve found and they said the way tuners is doing it is wrong.
They said their harness is made like buschurs, sparktech, etc.
I’ve read that if I run the COP in the first configuration that I can blow the PTU but if I run it in the 2nd configuration that I will lose spark.
Here’s a screenshot of the message from the company.
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My COP setup will be ran with a Dynatek Arc-2 if that makes a difference.
Any information would be greatly appreciated.

Details-
98 GSX
6 bolt swapped
Hx35
Ecmlink v3
SD

Here’s a picture of my money pit...
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Tyeler18

Proven Member
2,475
204
Dec 16, 2008
Casa Grande, Arizona
Since it wasn’t helpful on Facebook i'll write it again-

300m coils are super powerful when wired properly (stock Chrysler, aka in parallel). The problem is the resistance. The factory ecu/PTU can’t handle the load of having 300m coils wired in parallel. It WILL blow the PTU or ecu driver (I’ve had this happen multiple times). That’s why we wire them in series, it keeps factory like resistance to OE coils but in doing so cuts the output down to ~1/3 what they produce in parallel. BUT it keeps the ecu happy.

If you’re running a CDI box you can wire them in parallel. The CDI takes the load rather than the PTU/ECU. PTU/ECU basically just become a trigger relay. So as I said on Facebook, stock- wire in series. CDI- wire in parallel.

Also if you want a better COP setup without the hassle or drawbacks of a 300m/CDI, Toyota Denso 4 wire coils are way better. A lot of models come with them but Prius coils are the easiest to find. They can be wired in parallel out of the box with no CDI as they have a built in igniter. They fit the spark plug hole/height, and they’re as powerful as a properly wired 300m coil, and no CDI needed.

Evo guys make upwards of 800whp without issue. I run them in my Evo and my DSMs and I have far less headaches with them than any 300m setup I’ve ever used.
 

brads

DSM Wiseman
852
95
Oct 24, 2002
Alta Loma, California
300m coils are super powerful when wired properly (stock Chrysler, aka in parallel). The problem is the resistance. The factory ecu/PTU can’t handle the load of having 300m coils wired in parallel. It WILL blow the PTU or ecu driver (I’ve had this happen multiple times). That’s why we wire them in series, it keeps factory like resistance to OE coils but in doing so cuts the output down to ~1/3 what they produce in parallel. BUT it keeps the ecu happy.

Do you have any schematic showing the 300M coils being wired in parallel stock? Each going to their own driver on the ECU, is very different from parallel.

If you’re running a CDI box you can wire them in parallel. The CDI takes the load rather than the PTU/ECU. PTU/ECU basically just become a trigger relay. So as I said on Facebook, stock- wire in series. CDI- wire in parallel.

Wiring coils in parallel is almost always a bad idea. Who is this person selling a COP kit, and telling you that they should be in parallel?

The charge times should be fine with them in series. The coil charge is built up from current flowing through it.

The real reason you should almost never wire coils in parallel is somewhat complex. But basically, when 2 coils fire in parallel, one into a cylinder under compression, and one into the exhaust stroke, the one firing into the exhaust stroke will fire first because it takes less voltage. It the will pull energy away from the other coil primary. When you wire them in series, this doesn't happen.

A CDI will mask this somewhat, but it still is better to do series.

The only time that it makes sense to wire them in parallel, is if they are both going to the same cylinder. But I don't think we have many dual plug head DSMs around.
 

ThunderChild

Supporting VIP
3,760
1,125
Jan 5, 2012
Rathdrum, Idaho
Also if you want a better COP setup without the hassle or drawbacks of a 300m/CDI, Toyota Denso 4 wire coils are way better. A lot of models come with them but Prius coils are the easiest to find. They can be wired in parallel out of the box with no CDI as they have a built in igniter. They fit the spark plug hole/height, and they’re as powerful as a properly wired 300m coil, and no CDI needed.

Evo guys make upwards of 800whp without issue. I run them in my evo and my dsms and I have far less headaches with them than any 300m setup I’ve ever used.

Any chance you have a link to a diagram or write up for the denso coils? I'm contemplating doing this to clean things up.
 

punk3rz

Supporting Member
209
69
Jun 1, 2012
Surgoinsville, Tennessee
Do you have any schematic showing the 300M coils being wired in parallel stock? Each going to their own driver on the ECU, is very different from parallel.

Wiring coils in parallel is almost always a bad idea. Who is this person selling a COP kit, and telling you that they should be in parallel?

The charge times should be fine with them in series. The coil charge is built up from current flowing through it.

The real reason you should almost never wire coils in parallel is somewhat complex. But basically, when 2 coils fire in parallel, one into a cylinder under compression, and one into the exhaust stroke, the one firing into the exhaust stroke will fire first because it takes less voltage. It the will pull energy away from the other coil primary. When you wire them in series, this doesn't happen.

A CDI will mask this somewhat, but it still is better to do series.

The only time that it makes sense to wire them in parallel, is if they are both going to the same cylinder. But I don't think we have many dual plug head DSMs around.

The company is SSSperformance on eBay.
I ordered a cop kit for my evo and was impressed by the quality of their harness and new coils so decided to get some for the dsm as well.
I think I paid $185 shipped at the time I purchased them so I couldn’t complain.
I’ve contemplated the Toyota coils, but I think they’re extremely ugly.
 

motomattx

Proven Member
3,707
1,454
Dec 9, 2010
wampum, Pennsylvania
First off, there is NO dwell time/coil charge time when using a cdi system, so throw that nonsense out of the equation right now.
 

Tyeler18

Proven Member
2,475
204
Dec 16, 2008
Casa Grande, Arizona
You must be logged in to view this image or video.
Do you have any schematic showing the 300M coils being wired in parallel stock? Each going to their own driver on the ECU, is very different from parallel.



Wiring coils in parallel is almost always a bad idea. Who is this person selling a COP kit, and telling you that they should be in parallel?

The charge times should be fine with them in series. The coil charge is built up from current flowing through it.

The real reason you should almost never wire coils in parallel is somewhat complex. But basically, when 2 coils fire in parallel, one into a cylinder under compression, and one into the exhaust stroke, the one firing into the exhaust stroke will fire first because it takes less voltage. It the will pull energy away from the other coil primary. When you wire them in series, this doesn't happen.

A CDI will mask this somewhat, but it still is better to do series.

The only time that it makes sense to wire them in parallel, is if they are both going to the same cylinder. But I don't think we have many dual plug head DSMs around.

Sure do, a factory 300m is wired in parallel. They share a common 12v and the computer pulses ground. Obviously sequentially not wastedspark like a DSM but it’s still a parallel circuit. Unfortunately I can’t save photos from my shop program so the screen shot is kind of small to read. And in fact wiring in parallel or series will ALWAYS pull the exhaust coil first. Voltage always takes the path of least resistance regardless of parallel or series. The stock coils actually fire ONE way, it always fires the same direction so spark will always pulse through the same cylinder first regardless of whether it’s on the exhaust or compression stroke. The strike time is so minimal that it makes a negligible difference. You can actually watch this occur on an oscilloscope.

Output is always a function of resistance. That’s the nature of the beast, we’ve done coil output tests and wired in series drops output almost 1/3 of what a parallel wired coil fires at. This has been tested on a bench as well in real time on the car. Coil dwell for a 300m coil is irrelevant, a stock DSM ECU can’t alter dwell time, not that it matters. A coil can only run so much dwell before it maxes out the amount of energy it can build and just begins generating heat without potential energy. Factory dwell is right at the border of this change in energy. The whole purpose of the CDI is to gain that potential energy from wiring them in series since we can’t wire them parallel straight to the ECU. I’ll link a good thread on the Galant forum where a guy bench tested 300m coils in parallel and in series while altering dwell to see what he could achieve for output. In parallel they will always have more output due to the change in resistance seeing as how everything else voltage based remains constant.

http://www.galantvr4.org/ubbthreads/showflat.php?Number=920233

I don’t even use 300m coils anymore because of the headache they create. Every single 300m COP setup I’ve installed on a customer car has let me down. The ARC-2 helps, when it’s not being a unreliable turd, but 90% of the cars I’ve installed them on have gone back to a stock coil with no issue, the other 10% go to Denso coils and I’ve never once had an issue with them.
 
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brads

DSM Wiseman
852
95
Oct 24, 2002
Alta Loma, California
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Sure do, a factory 300m is wired in parallel. They share a common 12v and the computer pulses ground. Obviously sequentially not wastespark like a Dsm but it’s still a parallel circuit.

But do you have any schematics of the coils actually wired in parallel. Parallel means the endpoints are tied together. They both are tied to 12V, but are they tied together on the coil - side? Hint, if they are sequential, it means they are operating independently, and NOT tied together. The whole circuit could be parallel, but that is very different from coils in parallel. If you added a second DSM ignitor so you had 4 channels, then you could run it like the 300M, but firing at the same time. The coils would still not be paralleled though.

There is a reason for the coils never being in parallel from the factory. It has to do with what I posted before.

I contacted the manufacturer to let them know what I’ve found and they said the way tuners is doing it is wrong.
They said their harness is made like buschurs, sparktech, etc.

Buschur and sparktech were running the coils in series, not parallel. Unless they have changed something over the past few years, which I seriously doubt.

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I don’t even use 300m coils anymore because of the headache they create. Every single 300m COP setup I’ve installed on a customer car has let me down.

I never installed a 300M setup. When the 300M idea first started getting traction, I pointed out that it was a bad idea, and that the stock setup was better. I bench tested them, measured the characteristics and it was apparent they weren't that great an option. I told people a CDI would help, but a coil swap was still a waste of money. I think it only took ten years or so for DSMers to figure that out. Explaining why it was bad was a waste of my time.
 

brads

DSM Wiseman
852
95
Oct 24, 2002
Alta Loma, California
Since there still seems to be misunderstanding of parallel circuits, I am attaching a picture showing what actual coils in parallel would look like.
Figure 1 is the 300M circuit. Note that the coil wire labeled coil - ( the coil negative) for the 2 coils does not connect. They are driven separately inside the ECU. This is basically the same as the 2 stock DSM coils, the main difference is that the DSM coils are waste spark, meaning they have 2 outputs.

Figure 2 shows 2 coils actually wired in parallel. To be connected in parallel, it has to be connected at both ends. Some people are wiring the 300M coils this way.

In Figure 1, when the coil drivers shuts off dwell to fire the spark, the coil - wires both see a large voltage spike. But the way the coils work, the coil that is under compression would see a larger voltage spike. Since the coil - wires are isolated, each coil dumps its entire energy into the spark plug gap.

In Figure 2, when the coil driver shuts off dwell to fire the spark, the coil - wires see a large voltage spike, But the coil that is firing on the exhaust stroke will take less voltage to start the spark(2kV vs 20kV at the spark plug as an example) . Since it only takes 2kV to start the spark, the spike on the coil - will be much lower. And once the 2kV spark occurs on the exhaust spark coil, because that coil - is tied to the coil - of the coil that is trying to fire under compression, it will pull energy away from the firing coil. The exhaust spark coil pulls the voltage down at the shared coil - wire. Which weakens the spark you need. And it will do this every single firing, because whichever coil is firing on the exhaust stroke will pull energy from the other. This is because the 2 coils are ALWAYS connected together on the coil -.

The ONLY time it might make sense to do coils in parallel, is if you are firing a twin plug head. They will both be under the same compression every time. Even then, dual ignitions would be better.

Hopefully this clears up why just because the coils are both tied to 12V and the ECU, that doesn't make them parallel. And why parallel coils are bad. None of the original 300M coil conversions did that, they all did the coil wiring in series.

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sierra5

Probationary Member
17
2
Jun 11, 2012
Ozark, Missouri
What coils will you be using? If it's the Chrysler coils then don't waste your time. It's a cleaner look but not as good as stock. Most coils are 2 wire coils which are inductive so it has to charge up after every discharge. I'm running Toyota Prius coils which are 4 wire. 3 and 4 wire coils are capacitance discharge so one wire is always hot so it's always charged. They're upgrades on the evos
 

brads

DSM Wiseman
852
95
Oct 24, 2002
Alta Loma, California
Most all 3 and 4 wire coils are NOT CDI. The little transistor that is normally in the ECU(shown in the diagram I put up), is put into the coil assembly instead. But they still have to take time to charge just like the factory inductive coils.
 

motomattx

Proven Member
3,707
1,454
Dec 9, 2010
wampum, Pennsylvania
A cdi system outputs hundreds of volts to the primary of the coil vs 12v or less for a traditional ignition system.
 

sierra5

Probationary Member
17
2
Jun 11, 2012
Ozark, Missouri
It's not cdi I agree. For evos it's the same if not better spark than stock. The ptu will have to be bypassed to run these coils which does work. I just haven't figured out the tach signal yet. The 4th wire is tach but gotta figure out how that part works. It's the cleanest install you can do
 

Ian Badgett

Probationary Member
2
1
Aug 19, 2020
Prineville, Oregon
Since it wasn’t helpful on Facebook it write it again-

300m coils are super powerful when wired properly (stock Chrysler, aka in parallel). The problem is the resistance. The factory ecu/PTU can’t handle the load of having 300m coils wired in parallel. It WILL blow the PTU or ecu driver (I’ve had this happen multiple times). That’s why we wire them in series, it keeps factory like resistance to OE coils but in doing so cuts the output down to ~1/3 what they produce in parallel. BUT it keeps the ecu happy.

If you’re running a CDI box you can wire them in parallel. The CDI takes the load rather than the PTU/ECU. PTU/ECU basically just become a trigger relay. So as I said on Facebook, stock- wire in series. CDI- wire in parallel.

Also if you want a better COP setup without the hassle or drawbacks of a 300m/CDI, Toyota Denso 4 wire coils are way better. A lot of models come with them but Prius coils are the easiest to find. They can be wired in parallel out of the box with no CDI as they have a built in igniter. They fit the spark plug hole/height, and they’re as powerful as a properly wired 300m coil, and no CDI needed.

Evo guys make upwards of 800whp without issue. I run them in my evo and my dsms and I have far less headaches with them than any 300m setup I’ve ever used.
Quick question here. When wiring let’s say denso or gtr coils in parallel for a waste spark ignition do you bypass the ptu? Or do you leave it in the car? Asking for a friend who’s building a gtr cop set up as waste spark. It’s a 3 wire coil just like the 4 wire denso coils.

1 wire 12v
1 wire trigger from ecu
1 wire ground.
 

Tyeler18

Proven Member
2,475
204
Dec 16, 2008
Casa Grande, Arizona
Quick question here. When wiring let’s say denso or gtr coils in parallel for a waste spark ignition do you bypass the ptu? Or do you leave it in the car? Asking for a friend who’s building a gtr cop set up as waste spark. It’s a 3 wire coil just like the 4 wire denso coils.

1 wire 12v
1 wire trigger from ecu
1 wire ground.
Yes bypass the PTU. 1 wire is 12v, 1 is ground and then 2 triggers. One for 1/4 and one for 2/3. I use the tach wire on the densos to run the stock tach.
 

DG-FNR

Proven Member
229
44
Oct 21, 2002
Geary, NB_Canada
As it happens, I'm designing a system for 3SGT, which is basically a DSM with 2 extra cylinders / 1 extra ignition channel.

There is a Bosch part number 0221604800 which is an Audi R8 coil, that also appears to refer to a Denso 673-9302 coil... not sure how that works? Bosch makes the Denso coil? Vice versa? Same spec but 2 different manufacturers?

In any case, I have one of the 673-9302 coils coming so I can work out fitment , design of the support plate, etc. The mechanical stuff.

Have you got a part number (AMP probably) for the harness connector/pins?

Probably need to source the connector on the IPT so I can make an intermediate harness that plugs into the stock one.

Interesting that you pulled the IPT. That's probably safe given that these coils use logic-level triggers, but there's a part of me that likes the idea of an intermediary step between the ECU logic line and the coil, so long as the IPT doesn't impose delay on the signal. If the output line goes hot at the same time as the input line does, the IPT might act as an isolator/signal amplifier.

Or is it pulling signal to ground? Haven't looked too closely at the electrical side of this yet... I like the idea of not needing the ECU to sink a lot of current - and yes, it's supposed to be logic level, but shorts happen etc.

My ECU is an AEM Series 1, so there is that.

Back when I put the second (!) standalone ECU ever in a DSM - A GEMS EVO rally ECU in an enclosure made by ProEFI - we blew out 2 IPTs in rapid succession, and I never figured out why. An MSD DIS-II box replaced the IPT, and the car ran fine after that.

Just clued in that @brads is Sheriden Engineering. You and I have done business before. You still selling connectors?

 
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brads

DSM Wiseman
852
95
Oct 24, 2002
Alta Loma, California
Have you got a part number (AMP probably) for the harness connector/pins?
If the connectors are the same as the Toyota Denso connectors, they are Yazaki. This is one of the connectors for some Denso coils:


Probably need to source the connector on the IPT so I can make an intermediate harness that plugs into the stock one.
The male side to your 6 pin IPT plug does not exist, that I am aware of. It is like the 7 pin plug on the DSM, but 1 less terminal. The DSM mating connector had to be custom made. I am pretty sure your IPT plug would need to be custom made too. I do have the 3 pin connector mate for your IPT, but that isn't the important connector.


Interesting that you pulled the IPT. That's probably safe given that these coils use logic-level triggers, but there's a part of me that likes the idea of an intermediary step between the ECU logic line and the coil, so long as the IPT doesn't impose delay on the signal. If the output line goes hot at the same time as the input line does, the IPT might act as an isolator/signal amplifier.

Or is it pulling signal to ground? Haven't looked too closely at the electrical side of this yet... I like the idea of not needing the ECU to sink a lot of current - and yes, it's supposed to be logic level, but shorts happen etc.

People remove the PTU on CDI installs sometimes because they have problems with the PTU. When new, you are absolutely correct that the PTU provides some isolation between the 2 circuits. It can drive the signals to the coil or CDI much stronger than just the ECU, sometimes providing additional voltage swing over what the ECU does. When we were developing the ARC-2, we ran into issues with the GEMS ECMs where there output signal wasn't as strong as the stock ECUs, so it required a PTU to be added into the system. This was an odd case with an Evo 8 and early GEMS ECU, if I remember correctly.

In this case though, the important factor in adding or removing the PTU is making the signal polarity match. The ECU gives and Denso coil expects a transition to high voltage to start dwell, and a transition to ground to fire. The signal out of a PTU is flipped. They generally ground the output, when the input goes high. And they float the output high(open)when the input goes to ground.

Just clued in that @brads is Sheriden Engineering. You and I have done business before. You still selling connectors?

I am still selling the connectors and adapter harnesses. I even post on the 3S forums occasionally.
 

DG-FNR

Proven Member
229
44
Oct 21, 2002
Geary, NB_Canada
If the connectors are the same as the Toyota Denso connectors, they are Yazaki. This is one of the connectors for some Denso coils:
My electrical engineering these days has been building controllers and subsystems for machine tool CNC conversions. I have gotten very used to product spec sheets having mechanical drawings, an exact specification of the electrical properties of the widget in question, a list of part numbers for associated connectors and terminals, and usually downloadable 3D geometry.

I had forgotten how much automotive obfuscates design parameters.
The male side to your 6 pin IPT plug does not exist, that I am aware of. It is like the 7 pin plug on the DSM, but 1 less terminal. The DSM mating connector had to be custom made. I am pretty sure your IPT plug would need to be custom made too. I do have the 3 pin connector mate for your IPT, but that isn't the important connector.
Oh, I guarantee it exists, the Denso guy selected a connector from the Yazaki catalogue and then either designed his casting to match the male plug interface or straight-up copy-and-pasted Yazaki geometry onto his model. The trick is finding the damn thing. The Yazaki home page has 75 PDFs for connectors, grouped by product family. Worst-case, one can brute-force-search the catalogues until the right answer pops up. Best-case, a Yazaki rep answers a customer service ticket and straight-up tells you.

I am trying the latter; maybe I will get lucky.

In the meantime - ack. I should be be prepared to select an arbitrary 6-pin connector and graft it in.

3 ignition signal channels, power, ground, tach signal?
People remove the PTU on CDI installs sometimes because they have problems with the PTU. When new, you are absolutely correct that the PTU provides some isolation between the 2 circuits. It can drive the signals to the coil or CDI much stronger than just the ECU, sometimes providing additional voltage swing over what the ECU does. When we were developing the ARC-2, we ran into issues with the GEMS ECMs where there output signal wasn't as strong as the stock ECUs, so it required a PTU to be added into the system. This was an odd case with an Evo 8 and early GEMS ECU, if I remember correctly.
Huh.

My GEMS had no problem triggering the IPT, I suspect the problem I had was that the dwell was set up wrong (easy to believe in those days) and I was just running too much current through the thing by holding it open for too long.
In this case though, the important factor in adding or removing the PTU is making the signal polarity match. The ECU gives and Denso coil expects a transition to high voltage to start dwell, and a transition to ground to fire. The signal out of a PTU is flipped. They generally ground the output, when the input goes high. And they float the output high(open)when the input goes to ground.
Ah, fair point.

I wonder if the AEM EMS can be programmatically changed to be active low or active high, like my CNC controllers can.

It has been a while since I've been in the software.
I am still selling the connectors and adapter harnesses. I even post on the 3S forums occasionally.
You used to have a website - I know I bought individual connectors from you before.

Aha! I had you linked from here: https://www.shapeways.com/product/D...ator-backcap?optionId=61183190&li=marketplace

Do you know which connector plugs into an EVO 8 MAF?
 

brads

DSM Wiseman
852
95
Oct 24, 2002
Alta Loma, California
Oh, I guarantee it exists, the Denso guy selected a connector from the Yazaki catalogue and then either designed his casting to match the male plug interface or straight-up copy-and-pasted Yazaki geometry onto his model. The trick is finding the damn thing. The Yazaki home page has 75 PDFs for connectors, grouped by product family. Worst-case, one can brute-force-search the catalogues until the right answer pops up. Best-case, a Yazaki rep answers a customer service ticket and straight-up tells you.

I am trying the latter; maybe I will get lucky.
The manufacturers make some series of connectors specifically for interface with sensors. They will make a drawing of what the connector that is molded into the sensor will look like. And they will make the harness connector that plugs into the sensor. But they will never make the connector that is on the sensor, in a wire harness version. I have seen quite a few series that were designed like that. You may be able to find a connector that is close enough to mate.

ECMTuning makes a 2G MAF connector mate for their speed density cables. The 2G MAF connector is the same as the 3S MAF, and is identical to the PTU connector, save for the # of terminals. The MAF side was never made as a wire harness connector by Yazaki. So ECMTuning had to get it molded themselves.


In the meantime - ack. I should be be prepared to select an arbitrary 6-pin connector and graft it in.

3 ignition signal channels, power, ground, tach signal?
I think you may need the 3 pin connector too, if you want power ground and tach. I think the 6 pin is the 3 coil channel in signals, and 3 coil outputs. The plug in mate to the 3 pin is on my website.


I wonder if the AEM EMS can be programmatically changed to be active low or active high, like my CNC controllers can.

It has been a while since I've been in the software.

I never programmed them, but I do recall hearing that was an option.

Do you know which connector plugs into an EVO 8 MAF?

I have them, just not on the website.
 
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