MiataBuzz

Hi all, I recently purchased a Miata racecar that has an MS3 Basic for a 01-05 Miata. This car still has the factory dash and wiring harness. I am looking to remove the factory harness or at the very least remove all of what is not needed to remove weight from car.
The MS3 Basic for Miata uses the factory Miata harness plugs. This car is already tuned so I am looking for help on what wires I can eliminate from the factory plugs at the ECU.
I got no info from previous owner and have not yet looked up info on the factory harness. Also as an FYI the car is a 97 but has an 02 motor. Not sure exactly what difference that makes.
I have wired many racecars using a Painless system. Just not sure what the ECU will need to see to operate correctly. Such as a check engine light.

Has anyone out there been here yet or can send a link to this issue?

Thanks in advance for any and all help!

thebeerbaron

iTrader: (1)

Keep the factory harness if it's working.

The amount of weight to be saved by tossing the factory harness is nothing compared to the headache of properly rewiring the car.

Wiring should be one of the last places you look to shed pounds and definitely after laying off the Christmas cookies.

MiataBuzz

The wire harness is at least 20 lbs so it has to go. If it was just a track car I would agree with you but this car will be vying for a National Championship at Laguna in 2022 and it has to be as light as possible to be competitive.

deezums

iTrader: (3)

You could go on a diet and start exercising and it'd be less painful both physically and mentally than trying to save weight removing what, 6 wires?

Especially so, since you apparently need to ask for help locating those 6 wires...

thebeerbaron

iTrader: (1)

I have most of my wiring harness out of the car. I just weighed it. It includes many of the wires you would need to keep. It weighs 14.5lbs.

I'm one of the guys who weighs cars for the regional NASA races. The amount of drama and all-around bullshit that happens because of cars that come in light is insane. The guy who trounces the pack by a second or more but is light by 2lbs really regrets his decision. Don't be that guy. Besides, if you're in one of the HP/weight classes, you're going to have to be very conservative on your stated HP to account for dyno variation. We're talking about 1-2hp here in terms of lbs/hp.

Seriously though, if you've listed the check engine light as a necessary wire, you're barking up the wrong tree. Leave the stock wiring alone except for the mods you need to make to run the '02 engine.

Alas, to answer your question though - you need the wires for the brake light, plus any wires that are connected to the MS3 Basic. Job done.

curly

iTrader: (25)

I've actually done this on a '93 shell that came with a '01 motor and harness. I don't think anyone has kept track of what you need to keep and what you can get rid of, me included. General rule of thumb is necessary sensors and outputs stay, along with powers, grounds, fuses, relays, charging/starting necessities, wipers, and race car **** like accusump, defrost, aim or other display, transponder, cool suit, etc.

But what everyone else has said is fairly good advice. I can count on zero fingers the racer's I've met that could see a consistent lap time benefit from removing a couple lbs. Concentrate on getting the most out of your setup and tires, and making sure your equipment is in perfect shape, then look into the rest.

codrus

IMHO the benefits of thinning the factory wiring harness are far exceeded by the risks of DNFing by introducing intermittent wiring faults by not leaving well-enough alone. If you want a car that's prepped as far as you can go, you're better off building a whole new harness with PDMs than trying to winnow out a 20 year old stock harness.

--Ian

ConeCrasher

iTrader: (1)

I’ve done this. Do I advise it, no. Would I do it again, probably. My ocd about certain parts of a race car require it of me. Your going to be on your own figuring what can go and what can stay. Print out the schematics for you harnesses and start crossing unneeded wires off. Whatever time you think it will take you multiply it by 10.

I am about to move to a different body and rather than reusing the old harness I punched a ms3pro evo ECU that comes with an 8’ harness. Everything will be new from scratch. I liked this option.

shuiend

iTrader: (24)

Horrible idea. It sounds great in theory. Then you start pulling to pull pins out of a harness that has been taped together for 20+ years. After a while you just hate your life. The amount of man hours to do it properly is a ton, more then you would ever want to pay someone to do.