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OE Toyota capacitor for COPS

Old 11-16-2015, 12:30 PM
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I searched through the COP threads and didn't see anything regarding the OE toyota capacitor that is part of the coil harness. Besides buying the recommended 10,000uf capacitor would the Toyota OE capacitor work just as well when making a COP harness.

I have read a lot of conflicting information regarding even needing the capacitor but my thought is, can't hurt to do it while im making the harness. Id rather wire it in and not need it than need it or get a noise annoyance and have to wire it in later.

Picture attached of this capacitor.
Attached Thumbnails OE Toyota capacitor for COPS-80-20151116_103352_ae493c05f5ddf179646d4e08c55d66fcc246d1d4.jpg  
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Old 11-16-2015, 12:37 PM
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your miata already has something similar on the coilpack wiring.
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Old 11-16-2015, 01:00 PM
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So why do you recommend using a 10,000uf capactior between 12+ and GND?

If that’s the case then all I have to do is wire the cops harness to the mazda harness and done?

I know this has been discussed a ton but reading through pages of discussion it was unclear if this was necessary or not.
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Old 11-16-2015, 01:10 PM
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Originally Posted by el maestro View Post
I know this has been discussed a ton but reading through pages of discussion it was unclear if this was necessary or not.
Adding additional capacitance between +12 and GND, as close as possible to the ignition coils, can only help decrease ripple and improve coil charging.

In the stock harness, at least on the 1.6 cars, the very tiny condenser is located quite some distance away from the coils. I never looked too closely at the 1.8 harnesses to see how much they differ.
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Old 11-16-2015, 01:31 PM
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So Joe if I place this Toyota capacitor close to the harness it will only help charge the coils and cause less of a ripple. Basically no harm done. The OE toyota capacitor seems to ground to the chassis since there is only one single wire going to it and a metal bracket is attached to the capacitor. Does it matter that the grounding point is not in the harness but to the chassis?

From what im understanding this capacitor will connect to +12 from the miata harness and ground to chassis. Being that its a 96 1.8L with two 3 pin connectors, does it matter which +12 v gets the capacitor...ie: cylinders 1&4 or 2&3?
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Old 11-16-2015, 02:09 PM
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Originally Posted by el maestro View Post
So Joe if I place this Toyota capacitor close to the harness it will only help charge the coils and cause less of a ripple. Basically no harm done.
No harm at all.

Excess capacitance is the enemy in high-frequency applications, but at DC, you can't get enough of it. All rectifier-style power supplies (well, the good ones, at least) have gobs of capacitor on their output, and DC-powered devices which tend to have highly transient current requirements (like audio amplifiers) also tend to have loads of capacitance on their power inputs. There is, after all, some scientific basis to support the use of the Hustler's-*****-sized external capacitors which the car stereo geeks love to show off.


Originally Posted by el maestro View Post
The OE toyota capacitor seems to ground to the chassis since there is only one single wire going to it and a metal bracket is attached to the capacitor. Does it matter that the grounding point is not in the harness but to the chassis?
In a perfect universe, both legs of the capacitor are connected as closely to the load as possible. Moving the (-) leg of the capacitor away from the load somewhat decreases its effectiveness, by requiring the current which its supplying to traverse the whole negative side of the harness to get to chassis.


Originally Posted by el maestro View Post
From what im understanding this capacitor will connect to +12 from the miata harness and ground to chassis. Being that its a 96 1.8L with two 3 pin connectors, does it matter which +12 v gets the capacitor...ie: cylinders 1&4 or 2&3?
For best results, connect the + side of the cap as closely as practical to the +12 wire going into the coils, and connect the - side as closely as possible to the GND side of the coils. In the 1.6 cars, this gets a little tricky since the coil GND is all the way out at the far end of the igniter. On all later cars, the coils are grounded locally.



I honestly have no idea why the OEM harnesses tend to have the condenser grounded to chassis. It's entirely possible that the smart people who design wiring harnesses at car companies know something I don't about this.
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Old 11-16-2015, 11:01 PM
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Thank you Joe you've been most helpful
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