adam87S4

Hello, I am going to be wiring up my megasquirt in a week and need a little clarification on the CAS shielded wires. Firstly, does it matter what kind of shielded wire is used, between braided and foil shield? Secondly, if foil shield is able to be used, there is an electronics store close to my area which has 4 conductor Foil shielded and 2 conductor foil shielded wire. They do not have twisted pair shielded, so my question is could i just run two separate 2 conductor foil shielded wires? One for the NE signal and one for the G signal? I am mostly following Aaron cakes guide and DIYautotunes guide, keeping in mind the slight differences between the two so I dont screw it up lol anyways any suggestion and help is appreciated.

Thanks,

Adam

MIDNFauciUSN

iTrader: (8)

1st... follow EITHER aaron's build OR diy's guide (either is fine).

Foil shielded is fine. (2) 2 conductor cables are fine too, just ground the shield to the ECU end.

adam87S4

Sweet, that will save me alot of trouble searching for braided. Im following Aaron cakes guide to wiring it into the car, but followed DIY for wiring the deal board properly. I wrote which pins are what for my setup so there shouldn't be a problem with itthanks thanks for letting me know.

killalot13601

iTrader: (5)

I just used 22ga 4 wire foil shielded on a FC.

adam87S4

Like all four wires together with one shield? No separation of the pairs?

MIDNFauciUSN

iTrader: (8)

it doesnt matter if they're shielded individually or as a whole...

you're not shielding them from themselves, you're shielding them from other sources of induced noise.

adam87S4

Ohhh k I thought it was from both themselves AND other sources haha my mistake. Anyways thanks alot, guess ill go pick up some of that wire for this weekend

adam87S4

Hey so I've gotten the shielded wire and started modifying my db37 wires. I noticed that the harness comes with one pair of shielded wires, im assuming those are for NE+ and NE- so my new question is can I just use that pair as they are and only add the shielded 2conductor for my G signal? So id only be adding one pair of shielded wire. That works right?

MIDNFauciUSN

iTrader: (8)

yep... but if that wire doesnt feed into the correct pin on the db37 for your application, you'd have to de-pin and move it.

adam87S4

I have pin 3 and 4 as G+and G-,the zeal vr+ is to spr1 which correspond to pins 3 and vr- is to spr2 which corresponds to pin 4 so id add the shielded to the wires coming from pin 3 and 4. Then ground the to one of the megasquirt ground wires. Im guessing what I said about the NE signal going to the stock squirt harness is okay then?

Aaron Cake

iTrader: (1)

If we are talking about the typical DIYAutoTune harness, the two shielded wires in the harness are for NE+ and NE-. You just need to set the jumpers on the board to route them to VRIN (or VRINV depending on CPU). Then use the Zeal, MS3X board or LM1815 circuit for G. Your added shielded 2 conductor will be G+ and G- with G- grounded to the 2nd VR circuit and the shield grounded to the main ECU ground.

adam87S4

Awesome, that's exactly what I've done still haven't wired it into the car yet but now I know im doing it right lol

adam87S4

Which wire exactly is it that I can get ignition switched 12V from? I know its by the trailing coil wires but I just dont know which one or how to go about it?

MIDNFauciUSN

iTrader: (8)

From memory, it was a (green?) 6 pin connector. I didn't have a switched 12V wire in that harness though, so I found another one in the engine bay and used it.

Just throw your multimeter on it and measure voltage. Verify that 12V goes to 0V when key is turned off. About the most basic possible use of a multimeter. (If you already know how to use one, I'm not trying to be condescending, just trying to help - sorry).

adam87S4

Lol dont worry no offence taken, i was originally going to do that anyways but figured I'd try asking if anyone knew the exact one

adam87S4

Wired the engine bay today, had a couple questions...
The IAT CLT and TPS share the "sensor ground" wire in the general schematic of wiring diagram. So it is okay to join each of those sensors ground wires to that wire right? Or should I just run individual ground wires and leave the "sensor ground" wire unused?

killalot13601

iTrader: (5)

I have always combined them with positive results.

MIDNFauciUSN

iTrader: (8)

yep... using it is fine.

adam87S4

Finished all the wiring today, I was wondering if there is some way to test that all my sensors are hooked up correctly through tunerstudio? Im using ms2 with v3 board. In Aaron cakes video of his ms3 pro installation he shows near the end a test of each of the wired in parts, is that only for ms3 pro?

Aaron Cake

iTrader: (1)

MS2 has limited test mode with the most current firmware. I just fired up TunerStudio and it's under Advanced -> Output test mode. Allows you to test fuel pump output, injectors, coils. There is also an idle valve test in the same menu.

If you have other outputs (ie. fan) then just set their parameters to activate...ie. set fan on temp to 10 degrees or something.

But testing the sensors is easy. CLT and IAT should both show ambiant temp within a few degrees. MAP should show atmospheric within a KPA or two, then you can suck and blow in the hose to get a reading. You can suck down quite a vacuum but if you can blow more than 1 PSI you win a cookie. TPS is easy, just move the throttle around.

MS3 and MS3-Pro have a much more robust test mode.

adam87S4

Awesome thanks for the help, ill be getting to it tmrw and checking everything out

Vicoor

As much as we spend on everything else there's no good reason to cut corners on wire.

There are a lot of suppliers online that can provide you with the necessary wire and other stuff to make a great harness

Steinair
Aircraft Spruce
Prowire USA
Waytek Wire
cable and wire care

So if you are not sure about what you have at hand look at these, or other, suppliers and get the good stuff.

adam87S4

So I followed Aaron cakes guide on configuring the megasquirt and am just wondering about a couple things. The "Trigger offset" is 60 on his write up and he says that is correct if the cas is stabbed in the stock location. Also he has "falling edge" going low as the input capture setting. Diyautotune has rising edge going low... Why is there a difference there?

adam87S4

Along with my last post I have ran into a speed bump on my way to megasquirt glory. It seems that when I turn the key to "on" my megasquirt and relays aren't getting 12 volts. The battery is charged, wires are correct and triple checked. The source im using is from one of the black/yellow wires from the trailing coil. I ran a wire from there to my main relay. The main problem is not only are any of my megasquirt components and relays getting 12 volts but the black/yellow wires aren't getting it either. What could be the cause of this? From what it says in Aarons write-up when the key is tuned to on there should be 12 volts at the black and yellow wires to the trailing coil... The main fuse is good along with all the others, unless there is a fuse in the drivers side panel near the clutch pedal that could cause this. Everything else has been tested so this is a really crappy wall to hit. All opinions are welcome and appreciated.

Thanks,

Adam

Aaron Cake

iTrader: (1)

My writeup is based on old firmware which was expecting certain ignition capture settings. I'd suggest following the DIY writeup for software settings as it is based on the most current firmware. I *really* need to update the MS2 section of my writeup for software as it is terribly obsolete. However since I don't have an MS2 running on a car I also don't want to work offline to make a map in case I make a mistake.

If you aren't getting 12V on the black/yellow wire then either the EGI fuse is removed or the main relay is disconnected. You should get a good solid click from the main relay when the key is set to RUN.

The black/yellow powers most of the car so I would't expect anything EFI related on the stock ECU to work without power on that wire either.

Or, is this not a 2nd gen? 1st gens use black/white (I think) and FDs use diety-knows-what.