FricFrac

I am currently building a custom MegaSquirt harness for my Mega Squirt III setup on my car. I build an adapter to interface into the stock harness to get everything up and running as close to stock as possible. Once I had that working well I pulled all the stock harness out and I'm just about done building a new harness to directly plug into the MS3 ECU with MS3X for sequential injection and distributorless ignition. It interfaces directly with the stock body harness so you don't need to cut your harness up and can easily return the car to it's stock form.

The stock engine harness is basically garbage. I have yet to see an original one where the shielding on the Dizzy side is still in good condition but given that it's exposed to the elements it's not fair to expect it too be. There is basically no shielding on anything other than the O2, the fuel pump control (don't care with MS) and the dizzy. An auto engine bay is full of EMI that can cause problems with any electronic fuel injection system. Look at a 240SX wiring diagram and you'll see that the manufacture shields almost all of the sensors. I've been researching a few other after market engine harnesses for other engines to see what the other guys have. The 2JZ, etc have a lot of after market stuff and they boast Raychem this and MIL spec that but only bits and pieces are they way they should be. I've seen a lot of "quality" harnesses that boast MIL spec and yet the sensor signals travel over a single vinyl coated wire. So again out of frustration we are left to do it ourselves. Fortunately this is my area of expertise and I'm currently developing a EMI hardened engine harness for the S130 and will be designing one for the S30 chassis. The basic design will allow for a plug and play to the stock body harness (on the S130 at this point in time - haven't done my homework on the S30 yet) to control the stock fuel pump relay and fuel pump circuit (the S30 harness will have it's own fuel pump control). It will have its own fuse system and relays. The main intent is performance first (EMI hardened and the highest quality cabling, etc) and asthetics as an important secondary. You should be able to pull out your stock S130 harness and plug this harness in with an excellent fit and finish. If you ever want to go back to a stock setup simply unplug the aftermarket and plug in the new harness - no cutting into anything. Currently the design has all sensors shielded and cabling for your Wideband 02 with fused power and shielded input. The knock sensor and CHTS are not used with MS3 but are included (shielded of course) in the harness should you wish to use them. There is the capability to unplug the injectors from a built in adapter to go from batch fire to plug directly into the 3X board for sequential injection. An optional crank fire or distributorless ignition harness is also being developed. Since each configuration may have slight variances as to where sensors are located each harness can be built for the particular application.

Working on a custom car can be frustrating under normal circumstances but trying to chase electronic gremlins can be a nightmare even for an Electronics Engineer. The purpose here is to have a harness that starts you off from a solid base so you aren't chasing your tail and you can concentrate on the rest of your build. Let me know what you guys think and what you would like to see from a properly engineered quality custom harness.

evandubya

I want get the connections from you, but I will eventually run megasquirt so if you get a finished product and price I'm more than willing to get one of these also!!

icice9

i might be interested as well

godjimm

Im very intrested as well. Im in the process of ms2.2 will the harness work? whats your est. price?

FricFrac

Some pictures of the harness progress....

venomgg

do you have pricing information?

FricFrac

I'm looking into having a factory assemble a harness kit. I expect it will run around $300 and plug directly into the stock body harness. That will be a budget build based on my design using standard wiring and shielded wires where required. I'll have to do pre orders if I'm having a factory make a small run. A profesionally hand built one with high quality cabling designed to last for years in a harsh environment with the best noise supression is going to be about $550. Those will be ones and twosies for the guys that have the money to spend to do it right for a car they want to hang on too. I'm looking into having a factory make up the budget kit because I think that's what most people are going to want.

FricFrac

Oh and I should note that diyautotune has a generic harness that you can use for $67 but by the time you add all the connectors, relays and pieces to fabricate the harness you're at about $250 and the harness isn't even shielded plus you need to figure out how to asemble the whole mess.

007max

I am definitely interested in the budget harness kit, I despise working on wiring almost as much as doing bodywork

FricFrac

It's slow going. I've got several prototypes and I almost have the first customer's kit ready to ship out. I'm doing the complete package for him including his MS3 setup, etc which I'm doing at the same time I'm converting my system over to distributorless. Once all the parts for that come in I'll be able to finish the project off then I can look into getting a small run of the "economy" harneses built. They are still going to be around $300 but for what you are getting it's a good deal and it will still be plug and play. I just have too much on the go and I don't want this to turn into a huge burden so I'm doing it as I have time. It's slow but it's in the works

PredatorZ

Knowing your background and that you have done this before, I was hoping you could recommend a parts list. Reading through one of the many megasquit sites its obvious there are a lot of options in what boards you chose and then how you set them up. I too would buy a pre-made harness. I am going to do a z31 MAP/ ecu upgrade. If I build the boards myself, or do the more DIY intensive option, what will I need to buy ? I seriously trust my soldering over most, so putting it together is cool with me. This is something I think my company could build, we do a lot of small run harnesses, some for a similar product for snow mobiles. We have had really good word at work, normally we do about 500k a month in orders, we are booked till May at or near a million a month... so lots of overtime for me .. woot, and a raise hopefully.