Random wiring question. Is it necessary to use a capacitor if I'm running the ignition coils sequential?

 

Thanks for the help. I'll be ordering some of that stuff shortly.

That link just makes me drool. The twisted pairs on the sensor wires is something I'll probably incorporate into this project actually.

 

the cap is never necessary

 

I suppose necessary was the wrong word. Recommended? Helpful? Beneficial?

 

I've finished the main connector on the engine side. The ignition coils will be on a separate harness. The brackets look kind of funny but they work. They'll look better painted black. Loving the Weatherpacks.

 

I believe it was described, by someone smarter than me, as pointless.

 

You probably want to epoxy that connector.

 

Isn't it for the tach? Run the tach off the computer.

 

I thought the resistor was for the tach if you run an MS. My tach and whole setup works fine with no cap or resistor on the stock ecu (I'm assuming we're talking about toyota coils).

 

No, the idea behind it was to help store some juice between sparks and prevent voltage drops. But I believe JasonC SBB said it was trivial and unnessecary and questioned why we all started adding them.

 

As I understand it, the tach on a 1.6 is a totally seperate circuit that never sees the computator and goes straight from the coils to the gauge. I'm ending that in my car and running the tach off the computer using NB sensors.

 

Thats how mine works too I believe. The 94-95 cars have the tach driver as one of the pins on the coils.

 

The black/wht wire. I cut it and run the tach off the computer.

 

the tach on the 90-95.5 is driven directly off the coils.

The dash tach is looking for 4 pulses per cycle. You need your signal input to cycle from low to high, ground to ~12v, in order for it to recieve one pulse.

So the tach signal acutally has power running through it; basically everytime the coil sparks, it's switched momentarily to 12v, where it then returns back to ground. The speed in which the coils fire and the signal getting switched from low to high sent out to the tach determines the needle poistion.

The reason we add the resistor is because the stock ECU provides a pull-up power for the tach signal, when we replace it with an aftermarket ECU, we tend to remove the pull-up.

So unless you build your ECU harness to provide that pull-up back to the B/W that leads to the ignitor/coils, we add it back in the diagnositics box between IG- (the tach signal to the dash) and B+ (12v).

Otherwise all 95.5+ miatas provide the tach output directly from the ECU.

 

On my 1994 Dimitris build it into the harness so all I had to do was cut the wires on the coil. I understand this is different on the 1.6 cars.

 

On 1.6 cars the trick I used was to send the signal from the ecu to the ignitor and connect the two middle pins together. This has been discussed before.

-Raj

 

if you remove the factory ECU, the "trick" has been tricked...

for example, my B/W and tach output wires are tied together in my COP harness, but if I removed the 1K pull-up resistor that I added later, I'd be without a dash tach.

All you are doing by this is reconnecting the pull-up from the ECU to the tach output wire since you've gutted the ignitor where the connection had orginially been made.

This has been disscussed before.

 

The Brain has spoken. Saves me some time. Thanks!

 

Finished the ignition coil wiring. (the engine side anyway) Got my Egr stuff blocked too.

 

That looks like ****.