Coil on Plug Honda Coils?

[wird06DSM]

WEll i put in a k20 today in a new si and now i got a set of coils and connectors for free with less than 50k miles on them. So would it be possible to use these on a COP setup?

 

[yepes281]

Just one question, why?

 

[guitarhero14]

Just one question, why?

Free COP setup, cleaner engine bay. I get it. It wont be for performance tho.

 

[wird06DSM]

SO the question is more like why not? But is it possible is the question .

 

[ramsack]

Anything is possible. You just have to figure out if they have their own drivers in them, or if they are plain coils. If they are a plain coil they can be wired up easily. You will lose spark output unless you have something to tune dwell time (DSMLINK). If they have their own drivers you would need to find out what kind of voltage triggers them, a rise or a fall, and how many volts. Falling edge are usually a 5v signal. Rising edge would be 12v. You would also have to wire it up skipping the power transistor. Then your tachometer won't work. Dwell would also have to be tuned this way.

 

[wird06DSM]

I wonder how am i gonna find this info?

 

[polarmoment]

I wonder how am i gonna find this info?

Brave the waters of honda-(no)tech.

I can tell you that they do have their own drivers built in. They are VERY long- like, retarded long for a DSM head, and cannot be shortened without destroying them (or at least the K series coils I have in the garage are).

I'm fairly certain they're a 5v falling edge trigger. I could be wrong though, since I know the older distributor honda stuff is all rising edge trigger (I run a P75 as engine management on my MR2). So I can't speak for honda coils, but toyota coils typically have dwell control built in as well.

If you need to generate a tach signal, just tap a transistor via a diode into the ignition trigger lines and have the transistor drive a relay. Remove the clicky bits so just the coil is energizing. Connect that to the tacho interface. All it needs is a voltage spike above 20V or so to generate a tach signal, which the CEMF of the relay coil can accomplish quite easily.

 

[ramsack]

A relay generating a tach signal? You would just use 2 diodes. If more current is somehow needed then you need transistors.

 

[guitarhero14]

I wonder how am i gonna find this info?

I would suggest K20A.org .:. The K Series Source . Honda / Acura K20a k24a Engine Forum - Powered by vBulletin over honda-tech anyday.

 

[polarmoment]

A relay generating a tach signal? You would just use 2 diodes. If more current is somehow needed then you need transistors.

It's usually not that easy. It takes something like 20-30V to drive most tachometers. They're triggered from the inductive kick (usually 300V or so) that's generated when the coil turns off. That's what the relay is for- to provide an inductive kick of enough voltage. The transistor is necessary to pass enough current through the relay coil to create that kick. If you were to just use diodes from the main signal line, it's possible that the tach would drop enough voltage from the signal that it wouldn't be able to fire the coils anymore.

Granted, some tachs will run off a 12v square wave, but most OEM tachs need more voltage. Since the tacho interface module is connected to the ground side of the ignition coils, it's reasonable to assume that it uses CEMF (counter-electromotive force) rather than a square wave, and uses zener diodes to clamp the voltage spike to a value the tach can tolerate.

 

[ramsack]

The factory tacho can run off a normal 12v square wave, as demonstrated that my Dynatek ARC-2 did it. I made an interface once for this dude's cavalier because he wanted a tach, and there was nowhere to tap for it that had a signal an aftermarket tach would like. So I used 2 small transistors and 2 diodes. Worked like a charm. The interface for the tacho does not operate like like you described at all. Proof is that when people wire for something like a CDI they use the interface module on the triggers coming from the ecu to couple them, and it still drives the tach.