Direct Wiring Coil Packs

[VSPECII33R]

Guys, i remember reading something on here about direct wiring the coil pack harness to the battery, which would in turn increase spark at each coil. Anyone have any idea what i am on about & can run me through it please??

[Piggaz]

:\. Doesnt sound right. How does it know when to fire?

Sure you're not thinking fuel pump?

[VSPECII33R]

I think it was more along the lines of running a wire from battery to existing harness, so as to still get signal from the ecu. Had a diagram somewhere, but can't find it now that i actually need it Haha

[GTSBoy]

Firing is triggered on the earth side at the ECU.

[r32-25t]

Firing is triggered on the earth side at the ECU.

^this^

[VSPECII33R]

So does anyone know how to increase voltage to the 'positive' side? I remember something about direct wiring the power wire to the battery, but which wire is power in a 33 GTR coil pack harness??

[GTScotT]

It will be the only wire with 12v at the main 6 pin plug, when you test it with a test light. Generally there will be a white wire to every coil, daisy chained along, which will be 12v.

Running it straight to the batter will be fine, all that will do is aid in fixing perished wiring. If there isnt heaps of resistance across that circuit or its not showing low voltage I wouldn't bother.

[VSPECII33R]

Cheers Scott!

[GTScotT]

Don't quote me on the colour is all, I remember my SR was white but the colour codes for wiring can be different across models.

Just use the test light like I said and it will be the only one.

Don't forget to use a high amperage relay triggered by the original 12v wire.

[VSPECII33R]

Will do!

[GTSBoy]

And a fuse for chrissake.

[GTScotT]

And a fuse for chrissake.

LOL

[VSPECII33R]

Where should i test resistance?

[GTSBoy]

You're not looking for resistance measurements. You're looking for 12V.

You connect the black lead of the meter to earth somewhere in the engine bay and use the red lead probe the backs of the pins on the coil wiring loom where it comes off the ignitor. You have to push the probe into the back of the connector parallel to the wire until you hit the connector's pin. No contact, no measurement. As described above, the main power wire to the coils comes from there and daisy chains along the coils.

You have to have the ignition on to do this, obviously.

cheers

[VSPECII33R]

Ok cool, so it's only the power source not coming through as a true 12V that can cause the weak spark, not excessive resistance? Cheers!

[Shoota_77]

It's not just voltage that's important but amperage as well. A higher gauge wire will flow more amps than thin gauge.

Think of electricity like water and hence wiring like hoses. Volts is pressure, amps is flow. A larger hose will obviously flow more water so a larger gauge wire will flow more amperage.

A thicker gauge wire will definately get more voltage and amperage to the coils but you would really next to utilise a spark checker to work out if it actually makes any difference or if the coils produce the same regardless.

It would definately be interesting to know.

Anyone done a proper test?

[GTSBoy]

It still has to earth through the other side of the coil loom. Fattening up the 12V side is only going to gain you

a) a little bit, and

b) only if you're not seeing full voltage at the coils now.

The mod is really just a lazy way of fixing a poor connector joint or similar that may be causing a voltage drop across it, instead of finding and fixing the real problem.

[Shoota_77]

I think we need someone with a spark tester to see if it makes any difference. Would be very interesting to see if it made any difference on a dyno too. It would be very easy to have it set up ready to be switched over to do back to back results under the exact same variables (temp, tank of fuel, etc).

Somebody do it!!!!!

[MrStabby]

You want to check that the voltage across the alternator terminals (battery terminals is probably a good enough substitute), is exactly the same as the voltage presented at the coils. It should be 14.x volts when the engine is running. If it is the same, there there is no sense in making any changes. If it lower, then you have a bad connection somewhere, could be the +14 side or the earth side. Also, consider that the signal aka switching side is probably fine with lower voltage - you need to make sure that the power side is the full 14.x

I doubt going to a higher gauge wire will make any difference, after all, V=IR for DC. Unless there's something about the switching making things a bit ACish...

[Shoota_77]

I feel like a school teacher (sorry!!) but we're getting a little hung up on volts but amps is more relevant to this argument. You can measure 12 volts across a circuit whether it's a single strand of wire or 50 strands of wire. The resistance is obviously a lot higher over one strand compared to 50 (water theory- small hose high flow, big hose high flow at the same pressure) which means that a lot less power flow occurs over the single wire than the 50.