For background i have a 97 gs, eagle rods/pisotons, ported head, crower cams,1200cc injectors, turbo kit(just installed), and just recieved my megasquirt from symtech. I would like to use none of the original ecu. I started the wiring, wired up air temp and coolant temp sensors, and the injector harness. The question i have is that some sensors such as the TPS, and crank position sensor have 3 wires coming from the stock sensor pigtail. Do i ground one, leave one, and run one to the megasquirt?? and if so, which ones? The o2 sensor has 4 wires running from it, what do i do here? Also a lil off subject but anyone got any form of estimate on power i could be expecting at 20psi? I will be running e85, i know its not possible to get close estimates but ive never built anything other than carbed v8's and i dont know what i could expect for power.

Welcome to the site.

First, learn to use the search function as much of this has been previously discussed.

Read this thread: http://forums.2gnt.com/dcboard.php?az=show_topic&forum=54&topic_id=4891&mesg_id=4904

Also download a copy of the service manual and reference the wiring diagrams. Reference the wire colors and you will understand which wire goes where.

http://nawdu.de/files/

Thanks alot for the quik reply but i am still very confused. As for cleaning out the factory wiring all i ever come up with in the search is reply's saying to use the search to find information on it :S I have stared at the megamanual for quite some time now and continue to become more and more confused. I believe i have found the wires on the tps and crank angle sensor that feed the ms but still am unsure what to do with the others? do they need power? in the wiring diagram symtech supplied it shows pin28 used as 12V to MS, which they show running to the injectors and to a relay hooked to the ignition switch. Does this wire also feed power to the other sensors? Or is that what this +5v Vref pin26 wire is for? I would think the wiring diagram would show what wire feeds the sensors. as for having these things ran by relays i was understanding that in the megamanual. Please help, im dying to drive this thing

Did you read the link I posted in my first reply? It clearly shows which wire colors need what for the sensors.

alright thanks, those help alot. None of the sensors have to be wired through a relay correct? just the injectors and coil right?

Correct, none of the sensors need a relay.

ok, last few questions i hope. How many sensors need a 5v source from the 5 vref wire? TPS, Crank position, and what else? and do the 6 black ground wires from the ecu go to the grounds from the sensors or do the sensors just get grounded somewhere on the car and the ecu wires just get grounded on the car somewhere?

Originally posted by reborn750
ok, last few questions i hope. How many sensors need a 5v source from the 5 vref wire? TPS, Crank position, and what else? and do the 6 black ground wires from the ecu go to the grounds from the sensors or do the sensors just get grounded somewhere on the car and the ecu wires just get grounded on the car somewhere?

TPS needs 5v, from the vRef wire from the MS. Crank, Cam, & Speed Sensor use 12 volts (pull directly from ASD relay or switched 12 volt source). If you do not care about the speed sensor and are not using the cam input, then disregard connecting them. All grounds - ones from MS unit and sensors - should preferably be at a single solid chassis ground point.

Again, this information is all in the MegaSquirt manual.

sorry i guess, i have been reading on megamanual til my eyes bleed, i must not be looking hard enough for the answers to some of my questions. Here are a few of my new questoins as i am finishing up my wiring.

I have 4 wires labeled IAC1-A(blue w/ white stripe), IAC1-B(white w/ blue stripe), IAC2-A(white w/ green stripe), IAC2-B(green w/ white stripe). I have no idea what to do with them. A paper that i recieved from symtech with my ecu says

High Current GPO- IAC2-White/green
tach Output-IAC2-Blue/White

What wires go where?

Also in my wiring diagram it says brown wire goes to coil cyl. 2 and 3, and that green w/white stripe goes to coil cyl. 1 and 4. but my wiring only has a brown wire in it for the coil. The only other wires i have left are for the fuel pump, and o2 sensor. Am i missing a wire?

If the paper from Symtech states the IAC2 - blue/white wire is for TACHO output then it is to be used for your stock tachometer or an aftermarket tach if you have one.

The High Current GPO IAC2 - white/green is for whatever you want to drive or switch on/off by the MS.

Are you going to run ignition with your MS? If so then you need to connect your ignition output wires to you ignition coil in order to drive it.

If you appear to be missing a wire, I would contact Symtech and speak with them about your harness. Ideally you should have checked for all the needed wires prior to installing/soldering your harness. If you need to send the harness back in for service, you need to cut it back out to remove it, if you are in fact missing a wire.

Originally posted by reborn750
I have 4 wires labeled ... IAC2-B(green w/ white stripe).

Originally posted by reborn750
Also in my wiring diagram it says brown wire goes to coil cyl. 2 and 3, and that green w/white stripe goes to coil cyl. 1 and 4. but my wiring only has a brown wire in it for the coil. The only other wires i have left are for the fuel pump, and o2 sensor. Am i missing a wire?

You're not missing a wire, you just said you have a green/white wire. This one goes to the coil for cylinders 1 & 4, while the brown wire goes to the coil for cylinders 2 & 3.

yes, thank you i finally figured that out after reviewing the forms symtech gave me, finally getting somewhere close with my project