As I continue my research/learning process while I try to secure a good clean chassis for my build, I have come to the last thing on my list that I still feel leary about......wiring. You remember those videos from AFV where the blindfolded child hits their father in the you know where while trying to hit a pinata? I don't feel too far from that.

All that being said, I will start with a few basic questions and hopefully build on some of your advice. Once done, my miata should have an engine computer that basically gets power from the ignition and controls all functions and sensors throughout. It will have its own fuse module, and will communicate with the dash. Then there will be wiring from the car itself that will also have its own fuse module that controls everything else like lights, radio, windows, etc. Does this all sound correct? Does the ECM control the AC/Fans?

As I have been doing some research, I have been considering buying a new standalone harness to simplify some things. I have a company local to me that creates standalone ECM harnesses to the customers needs that looks to be pretty nice, please see their ad and site:

1999-02 LS1 5.7L Cable Throttle Fuel Injection Wiring Harness
TechRods Home

Does this seem like a decent option for someone like me that is nervous about the wiring, or am I way overthinking it? I have the harness from my donor camaro up to just past the bulkhead connection, it is cut from there.

 

No V8 Miata men don't need stand alones! Those were designed for the pro touring wimps that have so much room under the hood they don't know what to do with it all. We are the men of the V8 Miata and we conquer all!

LOL - Yes you are way over thinking it! It's really easy IF you don't focus so much on the big picture. When it comes down to it all you need to do is verify about 30 wires are going where they are suppose to go. If you can tell colors apart, can follow a string and (this is the key) only focus on one wire at a time there is nothing too it.

The computer on an 02 F body has about 125 wires going to it nearly all of which are already run for you and you don't touch. The ones that are not are spelled out very well here. Nathan's LS1 Miata

He also used an 02 and I found all of his wire colors and directions spot on.

So the hardest part is the mental game and as you can see on Nathans site it's only 15 steps and nothing to be afraid of. The next hardest is the wiring diet. I actually skipped much of the wiring diet and it was a big mistake. The best place I know of to illustrate the wiring diet is our own ToySnake. https://www.v8miata.net/general-moto...age5/#post6809

Yeah it is a heck of a lot of work but take it from someone who skipped most of this step - JUST DO IT!

For reference as you will be needing it... Miata Forumz - Mazda Miata Chat Forums

 

Wow, I had not seen nathans site somehow.....thanks a lot Jim, the warm and fuzzy feeling is now getting more realistic.

 

Now your talkin!

The thing about the stand alone harnesses (other than you are paying for something you already have) is they don't save you much work. You still need to cull all of the old engine management stuff out of the Miata harness, find a speedo solution, etc. The other advantage to using the F body engine harness is you know will work with the engine and there is no bugs in it. And it's really not hard at all to make into a stand alone harness.... if I can do it anyone can!

 

I have this harness GM LS | Vortec V8 Throttle Cable
Its the nicest harness I've ever seen. And they re route it in a way that its pretty hidden. They also make their own coil pack harness that comes with it. And finally they allow you to customize all the connectors so you can pick and choose what you need instead of cutting and splicing new pig tails if you want to run ID1000 injectors or an LS7 maf. Its up to you really, if you already have a harness with an engine and its complete then I'd probably use it, if not then a standalone harness would be a nice purchase that will save you some time and probably look better than a harness that was meant for a camaro and re routed and chopped for a miata. That's just me.

 

i had a complete pullout at one point but i am getting a new wiring made also
i figure that i can sell my old harness for $250+, and get a new one made for $500 ... its not a bad deal

 

No question a custom harness made for the application is easier than adapting the F body one but there is no re routing of the harness at all between the 2 cars. The computer is in the same spot in both cars and the wiring wraps around the back of the engine and goes to all the connectors exactly the same too. The car may be 25% smaller but the relationships to everything wired in the engine harness is the same.

 

I was apprehensive about the wiring myself but did it anyway to save some money. This website was very helpful LT1 Swap he tells you what wires to keep and which ones to delete. Keep in mind, you don't have to delete any wires...you will just end up with some extra wires around with pigtails on them that don't look very good. The guy that runs that website will delete vats, rear O2's, EGR and do other programming for you if you want for $75. I sent my pcm to him and had it back in about 10 days. He is also pretty quick about answering wiring questions via email.

 

I know there are guys that have had good luck with him and it's quite possible we just hit him at a really bad time in his life but Shannon and I both had bad experiences with him. He is cheap though and if you are not in a hurry probably worth it. For me after what I went through with him I decided I can't be dependent on someone else for something so simple so I picked up an HP tuners for 150 bucks so now I can tweak anything anytime I want.

It's too bad the license is so expensive because it takes about 5 minutes to do everything needed for a normal swap and I'd be glad to do it for nothing for anyone that wants it but the way the credits are set up to just do a couple computers would be 100 bucks each so for that you may as well use the LT1 guy.

 

Jim, How user friendly is that software? I am planning on installing a cam in my engine before it goes into the car, is that software going to help me tune to that type of thing?

keep in mind, I have ABSOLUTELY NOOOOO tuning experience.

 

LOL everyone starts with absolutely no experience! Stuff like disabling VATS and rear 02s is super easy and the software is very easy to use. BUT tuning is a different deal all together because there is so many variables. If you are running an off the shelf cam it's pretty easy to take some one else's known good tune and make fine adjustments for the Miata. That is one reason I went with the ASA cam. But if you are starting from scratch or doing a boosted set up it is very complicated. You can change spark timing, fuel timing and injector open time at literally every RPM just to name a few peramiters.

If you are going to just tune the car once and be done with it I would suggest paying the big bucks for a dyno tune by a pro. By the time you buy the tuner and wide band it's cheaper and probably a better tune that you would do on your own. But if you feel you might change cams, air filter set ups or gears as you grow into the car AND enjoy figuring out how to do stuff you never thought you could do then doing your own then a tuner can be cheaper and interesting to learn.

You can click on most of these buttons...


and it opens up into a table like this that you can edit.


To be fair most of the stuff on these two shots you would not ever mess with. Unless you want your idle to sound like it has a lot more cam in it than it really does... that's what I heard anyway...

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