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Hey all,

I've been looking at the thread for converting over to COP from Packs. I have a 97 Mustang GT that's currently NA; will be adding a CAI, Headers soon

The thread I've looked into is: forums.tccoa.com/675636-post88.html

There's a great write up on the conversion process. However, I did a google search for "coil pack vs cop", and one forum in particular got me thinking COP vs Coil Pack - Ford Mustang Forums : Corral.net Mustang Forum

In that forum, they talk about the "wasted spark". I'm confused with this as even in Coil Pack(CP) method, the packs are hooked together with 4 common wires (shown in the attached image). So even the CP's have a "wasted" spark. Two cylinders are always firing at the exact same time. That is, unless I'm missing something here.

Am I correct in this thinking? If there is an additional wasted spark, does it hurt, hinder, disrupt the normal operation of the engine, or cause reduced fuel economy? If not, does it help increase fuel economy? Is there more power to the wheels with a COP conversion?

Thanks,
Kori
 

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The wasted spark occurs near the top of the exhaust stroke of one cylinder, while it's companion cylinder is near the top of compression. It's a truly wasted spark because the fuel/oxygen mix was spent two strokes earlier.

Factory COP and COP conversions are different. Mustangs that come with COP have 8 individual trigger wires, no wasted spark. COP conversions are simply a way to eliminate the packs and plug wires for aesthetics/simplicity using the original 4 wire computer and wiring. There really are no gains to it, and in fact because the COPs need to be wired in series, due to impedance, the spark will be somewhat weaker with a COP conversion than the coil packs or individually fired COPs. The spark is still more than enough for a NA engine but high boost may result in spark blow out.
 

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Hmm, ok. thanks for clearing that up. So the wasted spark happens regardless on an NA pre-99 on packs or cops conversion.

I guess I'll just let it stay as it is and maybe do a reroute of the plug wires and put the packs on the firewall or such.

Thanks again :)
 

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The wasted spark occurs near the top of the exhaust stroke of one cylinder, while it's companion cylinder is near the top of compression. It's a truly wasted spark because the fuel/oxygen mix was spent two strokes earlier.

Factory COP and COP conversions are different. Mustangs that come with COP have 8 individual trigger wires, no wasted spark. COP conversions are simply a way to eliminate the packs and plug wires for aesthetics/simplicity using the original 4 wire computer and wiring. There really are no gains to it, and in fact because the COPs need to be wired in series, due to impedance, the spark will be somewhat weaker with a COP conversion than the coil packs or individually fired COPs. The spark is still more than enough for a NA engine but high boost may result in spark blow out.
The solution is to [easily] wire them in parallel to avoid any series losses. I did series wiring for safety's sake, but who's to say that it will hurt the coil pack drivers for sure? Only he who has a burnt PCM. So far, no one has come forth with actually trying parallel wiring and saying it does or doesn't work. Empirical evidence rules all. Damn I can't believe that was back in 2005. 12 Freakin years ago. I was ahead of my time :tongue:
 

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...Damn I can't believe that was back in 2005. 12 Freakin years ago. I was ahead of my time :tongue:
I haz Questions:

Has that Ignition actually fired a cylinder since?

And

Did you have the coils or plugs coated?

>:)
 

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The solution is to [easily] wire them in parallel to avoid any series losses. I did series wiring for safety's sake, but who's to say that it will hurt the coil pack drivers for sure? Only he who has a burnt PCM. So far, no one has come forth with actually trying parallel wiring and saying it does or doesn't work. Empirical evidence rules all. Damn I can't believe that was back in 2005. 12 Freakin years ago. I was ahead of my time :tongue:
Send me a MBE3 you're hoarding and I'll try it out :tongue:
 

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Send me a MBE3 you're hoarding and I'll try it out :tongue:
I have an FTE1 with transmission issues I'd donate to the cause; The drivers are a mosfet, supposedly it starts as a short, limits the current rise, then turns off hard.

It will probably split the current between the coils, and give a wimpy spark to both.

Series should be fine, as fast as these coils build current. (fast)
 

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I've never had any issues running COP in series, I'm just not sure I'd use them that way with boost(which I'm not into anyway) it would be interesting though to see how they'd do in parallel. In theory you'd be able to modify a stock COP engine harness and simply bridge the existing 1/6, 2/8, 3/5 and 4/7 wires together.

Course if they're weak(er?) in parallel then there's no benefit
 

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I've never had any issues running COP in series, I'm just not sure I'd use them that way with boost(which I'm not into anyway) it would be interesting though to see how they'd do in parallel. In theory you'd be able to modify a stock COP engine harness and simply bridge the existing 1/6, 2/8, 3/5 and 4/7 wires together.

Course if they're weak(er?) in parallel then there's no benefit
A few years ago I read an article where aside from the dwell time being limited, current is also limited by the pcm. Perhaps there won't be any ill consequences like there would be in a simplistic circuit where current draw is doubled with half the normal impedance. Try it out. Maybe it's the way to maximize the power available for boosted applications.
 

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Discussion Starter #11
Thanks guitar_maestro for adding in on the conversation. If I had a second setup, I'd try the parallel wiring and give it a shot to see what happens. But, being my dd, I don't think i'll be trying that :p

I think over all for the time being I'm going to stick with the stock wiring. I was hoping for a better burn and get more hp or efficiency. But if there's no real discernible difference between the two setups, I'll just leave it as is.
I know there is benefit putting in the other computer, but I'm not going to do that swap. A bit outta my leak for now.

Thanks again for all the input :)
 

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A few years ago I read an article where aside from the dwell time being limited, current is also limited by the pcm. ...
This is the waveform for a 2.3l ford dual coil setup:


This is what I was trying to say above; it ramps the current up to some value, based on the coil, and then dumps it, making the spark.

The pedestal length increases at lower rpm; the ramp is the shortest expected firing time, probably ~7k rpm. It can be measured with a scope.

If you put them in series, it really doesn't matter; they have the same current thru them; even in series, it never gets close to 12V at all.

The coils now are Current-fed, not voltage fed. :)

Big difference from the way a set of points worked them, lol.

The ramp in this graph would support 12k rpm. :)
 
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