Rotorhead34

Does it matter if the hot wires on the coils are hot with the key on or key off? Also, does it matter if the hot and ground for the ecu go straight to the battery or can they be switched as well.

Aaron Cake

iTrader: (1)

The wries that go to the coils need to be switched, otherwise you will have a constant power draw that will drag the battery down when the car is off.

The thick red and black need to be connected directly to a constant source of +12V and ground. I'm sure you can switch the big +12V if you want, but why?

Rotorhead34

I thought that was the way its suppose to go because I would think the ecu needs a constant 12v to retain its memory. I already have everything else wired, just the main 12v source is left to hook up and its running.

rx72c

iTrader: (8)

the coil packs can have live power all the time and will not drain the power as they dont operate unless switched by the computer which is ignition switched. i have done and tried this on many cars with no ill effects.

BluRR

iTrader: (1)

Once the ecu looses power..like the battery is disconnected, you loose your tune?

Rotorhead34

So if I disconnect the battery sometime down the road, I will have to retune the car?

Aaron Cake

iTrader: (1)

There will always be a draw from the ignitors if they are connected to 12V. This draw may not be large, but it will be there. Also it's quite sloppy to wire them like that. There's no reason why the coils need to be live with the rest of the car off.

Absolutely not.

BluRR

iTrader: (1)

I have a question. I have an lt-8s with the ecu adapter. I haven't installed it yet. Whats the proper way to install it? I was assuming to just plug it on and go. But i saw a post here where some1 said (maybe you aaron) that you shouldn't use the stock ecu power supply wire to power the microtech..cuz it will keep blowing the 15A engine fuse? If this is the case..what the correct procedure?

therealdeal

if you have the ecu adapter you can plug and go.
www.realdealmotorsport.com

BluRR

iTrader: (1)

so whats about blowing the 15A fuse if you use the original ecu power? or does the adapter take care of that?

rx72c

iTrader: (8)

im not sure why i even bother but for ***** sake i have tested this. their is no current draw.
it will not flatten the battery. their is no power draw at all.

Aaron Cake

iTrader: (1)

The original OEM ECU power is fused via a 7.5A fuse for the ECU, and something like a 15A "engine" fuse that controls some relays and I believe the fuel pump. I don't remember exactly so check the wiring diagram.

Either way that wiring is old and of thin gauge. The Microtech's thick power wire should be directly connected to 12V at the battery because not only does it power the Microtech, but also supplies power to the fuel injectors (about 4A each for low impedance).

If that's what you believe, then who am I to argue? But if I received a car from a shop with the coils wired to constant 12V, I'd be demanding a refund.

13bturbofc

iTrader: (4)

i dont really understand why some people even bother to use the stock harness when you can have the brand new microtech harness

BluRR

iTrader: (1)

so when you power straight from the battery, you put a relay and fuse in there? whats sizes? and do you put the relay to the ignition? as in turn on the ecu when the ignition key is turned to ACC. position?

Rotorhead34

Jon from microtech said to run it straight to the battery, which to me says no relay. Someone correct me if I'm wrong. The only thing you need a relay for is the fuel pump.

Aaron Cake

iTrader: (1)

What he said. The thick red and black wires go to the battery and ground, through a fuse of course.

The pink wire then goes to +12V IGN, which I generally tap from the black/yellow wire at the trailing coil.

The wiring diagrams are in the back of the manual, and at the Microtech website. If you do not have a manual, you can download one from the website as well as as wiring diagrams for popular applications.

Rotorhead34

I ran the pink wire to the black/yellow wire connector on the passenger side of the engine bay. I ran the pos coil wire to the trailing black/yellow wire. That way both are switched to the key. Still hot and ground(earth) are to the battery.

Where have some of you put the hand controller in the car? I'm thinking the dash pocket, but I also want to be able to watch it sometimes.