Questions during lt-8 install(CAS and fuel realy)
 

The diagram in the manuel says to connect red and green to the cas but gruond the others. The diagram doesn't make sence because it shows only 2 wires coming from the ecu when there are 4 CAS wires. My question mostly is that do i splice into stock harness or connect the 4 wires from ecu to 4 wires on cas, or do i conenct to and ground the other 2? I'm very confused about this.

Also do i have to get 12v on when fuel pump on for the fuel pump relay from the wiring back by the fuel pump or is there some wire under the hood i can use?

Regarding the CAS, connect the grounds to the ECU harness. The shield on the CAS line should also be connected to ground at the ECU.

For the fuel pump, the Microtech uses an open-collector switching setup to control a fuel pump relay. All this means for you is that the Microtech will provide the ground, and you need to supply a 12 volt source that will be on before, during, and after starting. You can wire this directly to the battery (I wouldn't) or to any place that meets the above requirements (e.g. coil packs, or any other IGN1 source, see the FSM).

umm i dont really understand what you are saying about the cas. do i plug each connector into stock ignition harness? a picture of this would help.

Also about the thing you said about fuel pump, i realize i messed up when typing but i am wondering if i can get a voltage forn the fuel pump from somewhere under the hood instead of all the way at the fuel pump.

Im not sure what your asking fuel pump wise but you got to run the wires tot he pump. My battery is located in the passenger side bin so put my relay in there and ran the signal wire fromt he microtech tot he relay then the power to the relay and the pump.

I reused my existing wiring harness and tied the LTX8 directly to it. except for the CAS where I ran the LTX wires directly to the crank and wired it in.

For the fuel pump, first I removed the factory resistor box (the gadget that adjusts voltage to pump depending on load/etc) and I rewired the wiring at that junction so my fuel pump nows gets constant 12V. I'll take a look today and tell you what wire I cut and which wire spliced into. It was simple.
I wired the LTX8 fuel pump signal wire directly into the stock harness wire that came from the stock ECU. Remember this wire just sends a ground to the fuel pump relay. Can't recall what color wire it was but if you look at the pinout of the turbo ECU you can figure out which wire. It's pinout 3K, I just looked at diagram.

i took my old harness adn junked it it was crap. but i need to know i still haev my stock ignition harness on the car that connects to CAS btu do i unplug car and use JUST the wires from microtech or do i need wires form microtech adn ones frmo stock harness? i ask this because doesnt it need to be hooked up to ignition switch so when i crank car cas turns?

Just reuse the connector; ditch the stock harness. I did the same as surfpac for the fuel pump, but I connected to the front harness using an extra connector I had from an old EM harness; no clipping required.

Since you have junked you harness, take the plug from the harness that conects to the CAS and cut it, leaving about 1 ft of wire with it. DO NOT GUIDE YOURSELF BY THE COLORS ON THE HARNESS PLUG. Guide yourself by the color on the CAS plug. (they are different). The two (2) wires out of the CAS plug (white/black, white) that are for ground, you don't need to conect to anything (the CAS is already grounded as well as the MicroTech). Conect the others as per the manual. SEE IMAGE

http://img.photobucket.com/albums/v282/stacher/CAS.jpg

As for the pump...my is a 91. I used the pink wire from the Microtech to the coil and the Microtech 12+ (red) going to the relay and then to the pump conector under the dash.

Hope it helps

Hey stacher, this might work for you, but I wouldn't recommend this wiring setup. By not using the ground leads from the CAS, you're effectively forcing the CAS' signal return path (i.e. its ground) to go through the engine, to the chassis, back to the ECU; this will introduce unwanted noise. The grounds that follow the CAS' signal lines, and the shielding of the Microtech's CAS harness are all there for a reason.

If you want to wire your CAS the best way possible while keeping the stock connectors: cut your front-harness CAS connector off as short as possible while still being able to solder it, and hook up both the primary and secondary triggers and their grounds. Leave the Microtech's CAS harness shield ungrounded (it's grounded at the Microtech, and you don't want to cause a ground loop through the shield). By keeping the CAS signal shielded as close as possible to the CAS itself, you can avoid transient ignition timing problems.

There's a useful schematic of the CAS on page 50-28 of the S4 FSM. Good luck.

maybe s5s are different but the fsm shows s4s haev same color on both sides of wires. i have mine hooked up like that greeg-green adn red-red. but i am gettign no spark.

stacher you are wrong i called microtech today and they said hook up all 4 wires. adn guess what? first try it started.

You guys kinda lost me. The color of the wires between the CAS and the CAS-plug were different than the color of the wires on my stock S5 harness. However, I just wired it up as per the Microtech diagram that came with the manual and it worked fine. Here was my thread about 8 months ago:

https://www.rx7club.com/showthread.p...&highlight=CAS

gergrx7.... Well, I only have 2 hooked up and guess what, it is running fine. When I did a "SEARCH", I found that "InfiniIV" had the same question several month ago and I got the answer out of the replies from his tread. It works fine for me so I ain't messing with it.

well, s4 and s5 must be different then because the colors on my stock harness were the same color as on the CAS. and the car got NO spark with 2 wires conencted btu started right up with all 4 connected. oh well, it runs im happy.

Thanks for the help.