Just found the following capacitor pretty local to me 10,000uf 16VDC. Will this work for the COPs on my 2000 Miata? I really don't know much about the electronic side of things and I believe others were using a 20VDC cap and this one is 16VDC.

No Idea on the price yet probably $5-7 for 1 unit.

Thanks for your help...

 

As is your case I have no clue whether that will work but; would you mind buying an extra one for me if it turns out it will work?

I'll paypal you the money.

Thanks,

Rafa

 

16V should be fine. Does it say 105*C or 85*C? If the latter it won't live very long in the engine bay. It will slowly lose capacitance over time.

 

Jason, are you by any chance running an AEM ems?

Sorry for the threadjacking Marc

 

Yes I am.

 

I dunno... This is all it mentions..

CEAUF1C103M10 CAP LYT RDL 10000UF 16V 22X35MM Marcon

 

it would be better to start with 20V as they break down over time. a 20V cap will have a longer useful life.

 

Ummm, can I get a quick explanation as to why you're looking into adding a capacitor to your COP setup?

I'm wondering if it's something that might help my 4k, light throttle, hiccup that I get w/ my COPs.

 

what does a large capacitor do? start from there....use the noggin.

 

Wire has resistance. The longer the wire, and the narrower the gauge, the higher the resistance.

The voltage drop across a conductor (the difference between the voltage you put in one end and the voltage you get out the other) is directly proportional to the amount of current being drawn down the conductor. As current increases, voltage decreases.

The total length of wire between the ignition harness and the Main Fuse (the primary voltage source, for all intents and purposes) is quite long, and the gauge of the wire is quite thin.

Ignition coils draw a large amount of current for a relatively short period of time, and then no current for a relatively long period of time.

So, when the ignition coils are on (during the dwell period) they are drawing a large amount of current, thus causing the voltage available to them to drop. This reduction in voltage at the coil primaries limits the amount of total power (volts x amps) that they can consume, which has the effect of limiting the total spark energy that they can produce. If a way could be found to increase the voltage available to the coils, then they could produce a stronger spark.

Capacitors are able to store and then deliver large amounts of energy for a short time. They are like miniature batteries.

By placing a large capacitor in close physical proximity to the ignition coils, the voltage drop at the coils is reduced considerably. The mechanism by which this occurs is:

1- At rest, the capacitor steadily takes in current through its positive terminal and stores it until the capacitor becomes saturated. Because it is drawing this current slowly (compared to an ignition coil) and over a longer period of time, it is able to saturate at the maximum possible voltage which the system can deliver.

2- When the ignition primary begins to charge, it draws a large amount of current down the harness, causing the aforementioned voltage drop. However, since the capacitor holds a large amount of stored energy at a voltage higher than what the harness voltage would be were it allowed to drop, the capacitor begins to discharge, feeding power out into the ignition coils. Because the coils are being supplied with additional power from the capacitor, they charge at a higher voltage than they otherwise would, allowing them to generate a larger spark.

3- When the coil primary shuts off, the now depleted capacitor once again begins to charge itself, and the process repeats.

 

thanks for answering me like a tool braineak.

and an honest thanks to joe perez, however I do understand what a capacitor is and I also understand how the capacitor will work in the car. My question was more along the lines of what problem is this aimed at solving.

I've had a diy COP ignition for about a year now(back when the wiring diagrams for the 1.6/1.8 was credited to lazzer) with no noticeable problems other than the 4k, light throttle, instant stumble I get now and then. I was trying to figure out if this additional mod would help rectify that. It doesn't seem like it would since the car's basically cruising when it happens, so its not drawing as much power to the COPs as it would be during WOT(during which I experience no problems).

I read a lot of the other thread about the 'dwell reducer circuit' for the COPs, and in there people were saying for a 1.6 (as my 92 is), it wasn't necessary.

In all, it seems like a pretty good mod to do, but I like to actually know the reason/purpose of a mod for my car instead of blindly spicing in capacitors.
Thanks again to Joe Perez. EDIT: I read the 1.6 AFM removal of yours. Very neat stuff and very well written.

 

you're welcomes.

 

Well, technically the coils draw the same amount of power on the primary side no matter what the load is. The difference is on the secondary side- as load (basically MAP) increases, the resistance on the plug gap increases. So the likelihood of a misfire increases with load because the secondary has to come up to a higher voltage in order to produce a spark.


Well, depends on your definition of "necessary."

The dwell time of the factory ECU on the 1.6 cars is ~5.5 milliseconds under normal operation conditions. I verified this myself by using an oscilloscope with an inductive DC ammeter on the primry side of my stock coils back when I was running an EMU.

Others have made a similar observation on the Toyota COP, and determined the optimal dwell time to be in the neighborhood of 2.5 milliseconds @ 12v.

The "problem" that the dwell reducer sets out to address is that if you leave the coil primaries energized for longer than is necessary (after they have reached saturation and the primary current has leveled) you are just creating additional heat in the coil primary without any benefit.

It is said that the 1.8 factory ECUs have a shorter dwell time, although I've not actually measured it myself. If this is the case, then in theory, the dwell reducer circuit would be more necessary on the 1.6 ECU.

 

Dang, I was hoping I didn't have to decipher that electrical diagram.

But thanks for the help Joe, I'mma get on buying/wiring all the necessary business.