Aftermarket Engine Harness
 

Does anyone know where/who would make an aftermarket engine harness for my '99 turbo motor?

The car is a full prep race car and only needs the engine harness and ecu plugs.

I have an extra factory harness, but I'm worried about cutting it apart and messing something up. I'm a nut and bolt/driver type of racer and not a fan of wiring etc.

Thx guys

No one.

There's nothing wrong with the OEM engine harness. Use it.

You either hack up the spare stocker and hope it works, or pay someone serious money for a custom one.

Spec miata guys would beg to differ.

Are they allowed to change them?

Spec Miata guy told me both the NA and NB Miata were "overbraked" from the factory and that I should ditch my "silly overwight 4 pot willwood calipers and enormous rotors" and instead run stock 1.8 brakes with Hawk Blacks.

Spec Miata guy told me I didn't need to ever check the shims on my solid lifter BP4W head.

Spec Miata guy told me to put Mobil 1 in my 5 speed.

Spec Miata guy told me that a stock ECU with the crystal changed out would give me better results than a megasquirt & wideband ever would.

In summary: So why don't you go ask the Spec Miata guys?

My :2cents:: Stock harness is fine. Get a wiring diagram and meter and cut out the shit you don't need/want and reloom it. Nothing is going to fit/work better than the stock harness.

If you feel the need to build your own, or pay someone a silly amount of money to do so, Ballenger Motorsports and Eastern Beaver can get you all the connectors you will ever need. If you built a "full prep race car" then something like an engine/ECU harness should be trivial.

step 0, buy a proper ratcheting crimping tool with multiple dies
step 1, buy all the OEM connectors you need with pins
step 2, buy motorsports/milsepc grade bulk head connectors with the correct amount of pins for things passing through the firewall
step 2.5, buy a power management system of your choice
step 3, buy proper automotive rated wiring in many different colors and stripe patterns and gauges, adhesive lined shrink wrap, and your choice of wire protectant material.
step 4, buy approximately 5 gallons worth of beer
step 4.5, acquire label making machine.
step 5, make time in your schedule enough to consume 5 gallons of beer and to wiring, make space to layout shit over 2 miatas worth of space
step 6, mix parts listed above in correct proportions.

SM guys are not held in high regard around these parts, so you're going to have to elaborate a little bit. What do SM guys not like about the factory engine harness?

I can see where he's going with this. Nothing is worse than trying to run a standalone on a wiring harness that some moron had previously fucked with.

And the factory wiring harness is larger than it needs to be.

However, if there's nothing wrong with your particular harness, then there's nothing wrong with your particular harness.

I've had issues with my factory harness. for a few reasons I believe.

1) It's going on 25 years old.

2) its been in the car for 320k miles

3) allot of time has been spent on tracks.

4) Its been fucked with, wires removed, re purposed, and added.

Exactly.

Each of those are things that would make me consider building a new harness.

All of them at once? New harness time.

I can tell.....There seems to be a growing contingent of people(myself included even though I don't race SM) that are having misfire/stumbling problems solved by replacing the harness. '99 is the most affected model. I have no idea if it "is" the harness itself or connectors or something else but replacing the harness "fixes" the problem. I'm sure many of them would replace their harness if they could.

My point being the oem harness may be ok but that doesn't mean one couldn't make, or have one made, that is better.

99-00 conectors that are in front of the valve cover are subject to bad connections, weather pack kit or better connectors solve that. Don't ask me how I discover that fact...

Redo the loops and put them near the firewall while you're at it.

You can buy a decent quality generic harness on fleabay or from summit for less than $200 - and that is for the whole car. An engine-only harness is likely to be a fair bit less.

Installation is a big job though and as was said, you end up having to carve up an OEM harness for the connectors and pigtails, or source new connectors which can be a challenge for some of the more unusual connectors.

My race car has a custom harness. I didn't build it but the PO must have spent weeks building it and putting it together. I probably wouldn't be so patient. I would hunt around for a good uncut harness, cut the unnecessary circuits out of it, and replace the dodgy harness with that. They are getting harder to find (especially engine, injector and ECU harnesses for certain models like 96-97 NA8) but they are still out there if you are patient and look hard enough.

custom wiring system
 

I dunno. I think a lot can be said for a custom wiring system, especially one with a single waterproof connection at the firewall that would be the only thing to disconnect when you take your engine out for work. Plus, we seemed to have left a lot of "extra" wiring laying around that could have been used as ballast. Or mouse food.

Thank you Cordycord for showing how much extra crap wire there is in these cars. Any chance you can tell me who made yours? Or would you make me one?

We make them in-house for the Catfish. Each one is different, so price is dependant on what's involved. Shoot me an email if you really are interested.

This is one of those things I go back and forth on.

1) Buy an unmolested wiring harness and yank everything not necessary

2) Over the span of a couple months, research and acquire the necessary motorsport centric connectors, wiring, heatshrink, snazzy loom, pins, firewall one port quick disconnect. Try to justify the baller RacePak Smartwire power control module. Run wiring to the trunk for superficial reasons and weight transfer. Cry as I wrap my brain around getting the lengths and routing 100% correct. Develop alcohol addiction. Pour gasoline on the car and dance around the flames in a fit of anger when everything doesn't work.

The OCD leans towards option 2. The sensible tells me not to fuck with it till I have issues and revel and seeing positive numbers in my bank account.

If you ever do Option 2, please take videos. :)

For the former portion of option 2 of course, not the latter!

Drunken mechanic YouTube videos could be a fun new series I could start... :rofl: