Hi guys,

My friend installed my Microtech last night and is almost done. One question I had. He said that the directions for the Microtech says to connect the positive power source for the microtech directly to the battery source (using an always on power source) and not to a switch. Is this right?

He has installed alot of other ecu's but never a microtech and he said that usually you hook up the power source to a wire that doesn't become hot until the ignition key goes to on and that there is usally a smaller wire that may hook to a constant power source to help with the memory.

As it sits he has it hooked to a constant power source but he wanted me to double check with you guys because he would prefer to hook it to a source that doesn't give power until the key is in the on position.

Can someone clarify this? What is the best way to power this bad boy?

This will be on an 85 rx-7 with a series 4 Turbo motor.





I'm getting so excited about this project I can hardly contain myself these days. Probably could have my car running real soon if I find the time.

thanks

 

From memory, the thick red wire goes to a constant 12V source. Generally this means directly to the batttery (via a fuse) or to a power distrobution point that connects to the battery.

Thick black wire goes to a GOOD ground.

The pink wire then connects to an IGN 12V source to turn on the ECU.

Most ECUs are powered this way including the Haltech and the (yuck) Wolf.

 

constant power ensure the ECU doesn't get reset everytime the car is turned off.

I just grounded the black wire to where the battery negative wire is grounded at on the engine on the same bolt. Couldn't get any better haha

 

No. The ECU will not reset if it loses power.

The thick red wire is the main power supply for the ECU. It uses this to drive the injectors (a significant amount of current) and run itself. Coil power is provided by the car. This is to avoid having to switch a large amount of current at every key-on event.

 

Ok, thanks for the info guys, sounds like he's wired the positive wire up the right way. It goes straight to a power source that goes from the battery to the fuse box in the first gen.

For the negative wires, I think there are two. He currently has them grounded to those two bungs on the top of the rotor housings (I think the top mount intercooler bracket used to attach here). One to the top of each rotor housing with a bolt through them attaching them to the engine. Is this location good enough for the grounding?

The main negative wire that runs off of the battery attaches to the back of the motor on one of the starter bolts.

thanks
John

 

i had it on the bolts on the rotor housing previousely too. But then i figured hey what the hell, the starter's negative bolt isn't that far away. I'll just make it on the same bolt for maximum grounding

 

Hmm, ok do you think the ones on the engine would be ok the way I have them now? My friend also suggested just grounding that neg cable from the battery onto one of those bungs since I will probably be relocating the battery to one of the storage bins in the near future.

thanks

 

it'll be fine. I was just **** and bolted it on the same bolt (the starter bolt) since my MT harness could reach it with out stretching or anything

 

I'm 100% sure that an LT8s has only ONE negative connection. It's a thick black wire. The LT8 series is the most common so since you have not mentioned which ECU you are using, I just guessed.

....Just looked up the LT10 and it also has one large ground wire.

So I'm not sure where the 2nd ground is coming from.

It is best to ground directly to the battery and to keep the ground wire as short as possible.

 

I can clear that up. The LT10s harness has it's MAIN black thick wire that's the negative that you ground. Then if i recall correctly (installed it last week, still finalizing the wiring) there's a few more ground wires (brown i think?) that goes to THE SENSORS AND SUCH. Each of the wires should be labled from microtech. They did on my harness. I took a multimeter to the harness and the big thick harness is in connection with the brown ones (i think they're brown, it's the negative wires for the sensors and such). Don't ground anything other then the thick black wire, the brown ones connects to whatever it's meant to on the diagram.


did that made sense? kinda typed it in a blur

 

Thanks for the info thus far guys, For some reason, mine has 2 grounds. Maybe because it's an LTX-8? Maybe there was an extra ground for the coils? Here's a couple pics although you can't see much. I do see the thicker black wire, then a thinner one. Like I mentioned, my friend is installing it so I will have to ask him what the second ground is for. I will probably try leaving the grounds where they are and see how it goes.

http://img.photobucket.com/albums/v2...n/IMG_0417.jpg

http://img.photobucket.com/albums/v2...n/IMG_0416.jpg

http://img.photobucket.com/albums/v2...n/IMG_0415.jpg

http://img.photobucket.com/albums/v2...n/IMG_0414.jpg

 

Yes, the brown wires are sensor grounds which don't need to be grounded (they connect to the black wire anyway....).

Looking up the LTX-8....

OK, LTX-8 does indeed have two grounds. Makes sense, because you want to keep the ignition ground seperate.

Now, I don't recommend that you ground them to the rotor housing. They should go to the battery. This keeps the connections accessable, away from engine bay heat and vibration, etc. Also, those connections don't look like they will survive long-term. Unsealed crimp terminals are very poor choices since they corrode like crazy and there does not seem to be any dielectric grease. At the very least, grease those suckers up. If they are available, use sealed crimps that have a sleeve of heat-shrink that gets shrunk after the crimp is made.

 

Ok, thanks for the info Aaron. All of the other connections are soldered then heat shrinked. I think he just used those because that's all we had at the time. I'll go out and get some better connectors and relocate them I fell better knowing that there is supposed to be 2 grounds

 

if ur engine is turboed, i don't recommend running it through the passenger side firewall. High temperature there

 

Do you mean running all of the wires that go into the microtech? Don't run them through the pass side firewall?

 

i didn't after debating for a while

the turbo does get really hot and some people i know has melted wires on that part of the car

 

I've always run standalone wires accross the turbo area. My thoughts are that heat is a much smaller problem then ignition interference. Generally I run the wires on the top of the little lip on the firewall which seems to be a very effective shield. Heat insulating wraps for wires are also available at better automotive stores and electrical suppliers.

And of course, the turbo should be shielded as well with a heatshield or heat wrap.