Ignition wiring sanity check
 

I'm getting ever closer to installing my stand alone (in fact I'm planning on wiring the power side of things tomorrow and crimping the cannon receptacle): I'm installing the quicksilver coils and want to wire them up on a plug prior to full installation. The trouble is they have no documentation that is sent with them. As such here's what I do have:

http://www.034motorsport.com/oscthum...ages/5-pin.png

I have 5 wires coming off from the ECU that will be connecting to these. 4 switched grounds (one for each coil) and a 12v switched source (don't worry it's relay'd).

My thinking is this:

A - 12V+ switched
B - Switched ground wire
C - Chassis Ground
D - Chassis Ground (or should I really run a wire to the battery ground?)
E - 12V+ Battery

Is this wrong, or is there a better way to wire this up? Thanks.

TTL means Transistor - Transistor Logic. This is almost always referring to a 5V signal.

There is no reason that I can think of that you should power your coils all the time (feed the Battery + with a switched source). The secondary ground should be connected as close to the spark plug as possible (this is the return path for the spark), the battery ground should be connected to a good ground point or the battery negative

Will the Platinum Sport ECU permit driving a coil at 5VDC instead of 12? (adjusting the pullup to 5V instead of 12V)? If so, you can invert the ignition output, drive the high at 5V and connect the low to the ignition output.

You can also ground the negative side and leave the output non-inverted (it will go high to energize the coil, fall to fire).

There are basically 2 things that you need to know. First, are the TTL inputs capable of accepting 12V (nominal - actually about 14V)? If not and second, can your ECU drive to 5V instead of 12V?

So if I can, mate the secondary ground to the engine itself? Got it. Battery ground can be mated to a good chassis ground?
No... it can't do ignition pull up like that... but I could do a DPO at 5v, or hook up the 5v sensor source to them which might work out easier.
I'm still waiting to hear back from 034 for the proper wiring schematic... As for the second I think I covered that pretty well.

Best way I've found is to daisy chain gnds from the battery with powerposts.

Ground all the aux crap, mack certain that the coil gnd is a damn good one, make certain that the positive is solid then of course there is the trigger

I found this recently:

Pin A - Ignition output from ECU
Pin B - ECU ground (chassis ground)
Pin C - Ground to the head
Pin D - Battery ground
Pin E - 12V+ switched

If you really want to get fancy you can run the ecu gnd back to the same gnd that the ecu shares. Other than that, just grnd the other 2 and call it a day. The coil gnd is the most important grnd to worry about.

So for Pin D can I ground it to the same location as Pin C without ill effect?

the D Pin is the main (-) for the coil. SO make certain that is a damn fine gnd and then yes, C can go to it without any ill effect.

I'm thinking of attaching it to the engine block itself, is that good enough? I've moved the battery to passenger bin so it would be a hassle to put it through the cannon plug unless it can work with a 20 AWG which I don't think would be good. I could run a 16 AWG wire for it, but I don't really want to attempt to shove it into the plug and would have to directly pass it through the firewall which doesn't look all that great.

I suppose I could measure the resistance between the point I intend and the negative battery cable in the cabin, which should give me a better idea if it's a good place or not. Is there a specific Ohm reading I should hope to see?

No

0

http://order.waytekwire.com/IMAGES/M...ms/47212FL.GIF

Grab one of those and put it on the firewall. Daisy chain the gnd from the battery, to the main powerpost, to that firewall piece, to the block, to the coils. Daisy chaining meaning that each stud has 2 terminals stacked on top of one another.

http://order.waytekwire.com/productd...0TYPE%20BLACK/

This is why I ask questions :)

Alright, I'll run a temp wire in the mean time until I get a bulkhead fitting.

No worries.... Waytek is awesome as they have quanitity min's not $$ mins. So you could order just that one piece. I wouldn't use anything under 18ga txl wire per coil.

Wait, you can't/shouldn't daisy chain 'em?

My setup is battery to powerpost, to engine block (one of the boss' on the rotor housings) to coil mounting bracket (I built it out of 1/4" AL plate and tapped an M6x1 bolt through it to make it a stud) to the individual coils. I'm saying if you run some sort of temp wire, don't go under 18ga per coil back to the gnd. Daisy chainin has served me well in the past