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Microtech Ideal place for ignition coil power source with Microtech

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Microtech Ideal place for ignition coil power source with Microtech

Old 07-10-06, 11:13 PM
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Ideal place for ignition coil power source with Microtech

ooooooooook well those of you who installed it should be able to help me out here

Coil's power wire is 14GA.

All of the Ignition 12V wires coming out of the fuse box @ the driver kick panel are 16GA or smaller from what I can tell by eye.

I'm already running the fuel pump and the ECU's 12V ignition power source from the original power source which is through the 15amp fuse at the driver kick panel. That original wire is something like 16GA.

Where do you guys get the ignition power from for your Leading and Trailing ignition coil packs?

I had everything hooked up and got my dad to check out the wiring for me and he pointed out that the power wires from the coil packs are bigger. I totally forgot about the whole wire heating up thing if it's not thick enough.


Is there some other fused wire i can tap in to, or should I just tap it directly in to the 12V ignition wire with an extra 40amp fuse? Since the FSM shows that the leading and trailing coil packs draws it's current directly from the battery through the 40amp fuse.

Any suggestion guys?
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Old 07-11-06, 07:57 AM
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I just run mine directly off the battery.
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Old 07-11-06, 08:57 AM
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This is in an '84?

If you are retrofitting the 2nd gen coils on, you will need to run your own power leads to the coils. At this point I always set up cars with an auxillary fuse box. This fuse box has a common lead that goes directly to the battery with a high amp (40A or so) fuse or breaker. The fuse box then has a fuse for the ECU, fuel pump, coils, etc.

In your case you will need to run power leads to the coils. Use 12 gauge wire. Switch this wire so that it is hot when IGN is on by using a relay. Your fuse should be 15A.

Here's a thread that covers much of my Microtech LT-8s install on my 2nd gen:
https://www.rx7club.com/forum/showthread.php?t=468413
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Old 07-11-06, 02:39 PM
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**** i apologize, forgot to say what car. It's for a S5 turbo engine (from japan, not that it makes a difference in this case) in a S4 NA chassis.

the pictures are so RED! lol

i'll read the whole thing when i get home tonight. Kinda slacking at work right now and the pics are taking forever to load
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Old 07-11-06, 02:54 PM
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lol oh my god. i'm pretty much doing the same thing. Only I've aquried another switch panel that controls all my accessories and ignition. But I wanna fire the microtech up before i go through the rest of the wirings again. Like to do things one at a time u know? I hate trying to trouble shoot something after doing 10 task and trying to figur out where I went wrong.

any one took a 12v ignition power source from an OEM location?

Kinda trying to stay away from running it straight from the battery since it doesn't give me the best feeling since it still has constant power even if the ecu is turned off.
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Old 07-13-06, 08:30 AM
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Ah, in an S4 it's easy. The coils are aready powered by the black/yellow wire when the key is set to IGN. So if you still have the body harness in place you are already set.

If the harness is in poor shape of you want to totally seperate the engine stuff from the stock wiring, then you will need to run some power wires to the coils as I mentioned above. They should be IGN switched with a relay, and fused for 15-20A or so. The trailing actually has two power connections but I always just power them both from the single 12 gauge coil wire.

As for taking power from the coils, you don't want to do it. The large red lead of the Microtech is used to power the unit and fire the injectors. Injectors draw much more current then people assume, on the order of about 4A a piece for low impedance. So firing 4 low impedance injectors means that the Microtech must supply 16A. Hence the reason for the thick power lead.

Almost every aftermarket ECU has constant power when the engine is turned off, so I wouldn't worry about it. If you are really concerned, then you can put a high current switch (at least 30A DC, high quality) in series with the feed from the battery to the Microtech. So you can turn it off if you really want to (theft deterrant...).
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Old 07-13-06, 03:36 PM
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the IGN relay is one of those silver box thing by the leading coils right? Gonna dig in to it tonight as i'm working right now

I was looking at other sections of the FSM the past few days to see if i can find any other wires and i remembered about the black\yellow stripe wires. Does the IGN relay ONLY power the 2 coil packs?

I'm kinda worried about overloading it as i know it needs a good power sources.

The microtech's red power wire is already supplying power to the fuel pump, so there's no way i can draw power from it safely for the coil packs.


and ya i realized the ECU always has constant power, what i meant was that when the car is off and the ecu is kinda in a hibernate(i guess?) mode however people would like to call it
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Old 07-14-06, 09:06 AM
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The mail EFI relay is located near the trailing coils. The pink wire is just a turn on wire, it hardly draws any current at all.

The thick wire needs to go to a constant high current source (battery, distro block, etc.). You can can put a switch on it if you want.

The fuel pump should NOT be powered through the Microtech's thick red wire. The pump needs a direct supply from the battery or distro block (fused). The Microtech then switches the pump via a relay.
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Old 07-14-06, 03:10 PM
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oh no no, the fuel pump is powered by the car's stock fuel wire for now. The MT's power wire just used for the relay

i tapped the MT directly to the battery terminal to save any hassle.

main EFI relay u mean? heh. is it the silver one or the other similar looking thing? been raining, and super busy. haven't looked at it just yet haha
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Old 07-16-06, 09:39 AM
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The stock pump wiring should be replaced. It is old, thin and corroding which will severely limit voltage to the pump under high currents (finding less then 10V is common). A 12 gauge feed from the battery/distro block (fused of course) controlled by the Microtech's relay is what you want. And a seperate ground running back to your main ground as well.

The man EFI relay is the silver box just at the trailing coil. There is a round connector on it that has thick wires. Supplies power to the entire engine system (fuel, ignition, etc.).
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Old 07-29-06, 10:12 PM
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hm...well i'm 100% sure i found the EFI box, but this seriousely puzzles me. The FSM says the black\yellow wire connects to the ignition coil power wire. But it's connected to this black thing that connects to the firewall....
Picture resolution Warning: 1836 x 1377
http://i97.photobucket.com/albums/l2...T/PICT0125.jpg

any idea aaron cake??
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Old 07-31-06, 11:06 AM
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The black thing is a capacitor which helps filter out voltage spikes caused by the coils.

All black/yellow wires in the engine bay are IGN 12V wires.
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Old 07-31-06, 03:47 PM
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so the black thing is suppose to be there!??!?

cuz i chk'd on my friend's fc, the black thing with hte ring on it doesn't have connection to the black\yellow wire connected. The black thing is connected to the ground wire on the relay and the black\yellow wire directly to the coils.

I must have been super tired when i connected that by mistake. I soldered the black\yellow wire to the coils already, so it should be good now...i hope haha
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Old 08-01-06, 11:12 AM
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MY question is, why don't you just leave the coils how they are stock, and just remove the signal wire and connect the pink wire to it. Thats how I did it, and its real simple.. The coils recieve power once the ign is turned on, regardless if the engine harness is there or the ecu, its ran by the body harness..
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Old 08-01-06, 01:58 PM
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cuz i got carried away one time and removed most of the harness on the driverside of the engine bay one day haha. I kinda got pissed at all the unused plugs from the stock NA chassis. Once this fires up, i'm redoing all the wiring to make it all simple.
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Old 08-01-06, 03:27 PM
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Yes, the black capacitor needs to be there. If your coils are powered indipendantly through their own harness, then don't worry about the capacitor.
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Old 08-01-06, 08:30 PM
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ohhh i thought it was some sorta ground. I guess the capacitor is kind hooked up in a Y joint. I guess that's why i did that as i took out the power wires for the ignition coils
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