CAS wire routing - seperate from rest of loom?
 

I heard a nasty rumor that it's very difficult to get a clean CAS reading on a megasquirt. True?

I have the newest MSIIIx (as of January 2014) and 12 foot loom pre built by DIY Auto Tune. I understand that I'll need to pull an additional 2-wire shielded for the G connections on the cas, though I haven't taken a close look yet at where to pin that in.

I'm currently half way through a full wire tuck in my FB GSL-SE and have routed the main fusible link power as well as lighting system harness through the drivers fender back to the cabin. There is also a 4ga stereo amp power wire in that loom.

The intake harness, iat, coolant temp, injectors, etc will go straight back the top of the engine and through a hole in the transmission tunnel. Cas wiring will drop straight down from cas, forward to the nose, then back along a fender.

While I've got everything apart now is the time to isolate things if necessary. My current thought is to route the CAS loom down the opposite fender, which would emulate the GSL SE distributor harness. I'm fairly certain I can make a route that will never once come within 3" of any other wires. This would also require taking off the other fender which my lazy side is not so keen on. But if it will prevent headaches I'm all for it.

Or is this even a concern? Will shielded wire be enough isolation to run along with the rest of the car's wires?

Thanks in advance, I'm SO excited about this build. It's really starting to come together, and I can't wait to dive into the tuning!

Geoff

In my experience, shielded wire alone is enough to keep noise under control. As long as you keep it away from noisy items (spark plug wires, coils) just like the OEMs do, you should be fine.

When I wire, I typically split the over-engine harness into two feeds. One around the injector area which feeds the injectors and CLT. Then another to the CAS area which deals with the CAS, IAT, TPS.

Dropping the CAS wire down (right past the spark plugs) and then routing it all the way around the car seems like a good way to introduce noise. I'd suggest using the hole in the transmission tunnel. This is what I've done in my Cosmo.