ECU Wiring questions

[agent4573]

I've installed the VG into a sandrail and am trying to clean up the wiring harness as much as possible. Here's what I've come up with so far and any input would be awesome. Just want to make sure I don't miss anything.

EGR, PRVR, AAC, AIV, and FICD will all be removed and clipped from the harness.

Connector F2 (the EFI to Main harness connector) is the tach signal. I'm going to leave the connect in as its a very short stub connector and doesn't really get in the way. I'll be running a separate switch to turn the fuel pump on/off as I'm not running a fuel pump control computer. I'm also planning on a Walbro 255 lph inline pump.

Connector F24 and all wires will be clipped from the harness as they only control A/T functions and I'm running a manual. Not even sure if that connector is in my harness, but if I find it, its gone. The ECU was from a manual car to begin with, so I'm kind of hoping I don't find it.

Connector F25 I have found, and will cut that connector from the harness completely. It appears that one of the orange wires in it trips the relay for the ECCS and the Ignition coils, so I'll just run that wire direct to the to relays I install for those functions, but here's my question. The ECCS flips that relay with Orange wire #16 from the ECCS. So if the ECCS has to be powered to trip that relay, what is the relay actually powering, since it can't be the main computer power. Does that relay just power all the sensors or ???

There are two connectors on the TPS sensor, one directly built into the case, and one that connects to a short dongle. I assume one is the Throttle valve switch and the other is the actual TPS. Is that correct?

The neutral safety switch: leave it open or ground it so that the ECCS thinks that I'm always in neutral? If I get it wrong the engine obviously won't crank, but this eliminates one more variable for when I try to turn it over. If I'm running the starter motor to an aftermarket switch, do I even need to worry about it? If the ECCS picks up signal from the CAM sensor, will it still fire the injectors/plugs even if the neutral switch is in the "wrong" position?

I think that's all for now. I'm sure I'll be back with more after I start cutting away wires. Thanks guys.

[NolimitZ32]

I wish I could help you but that would mean I'd have to go through all the diagrams and I just can't be bothered as its not a quick thing sorry. I will say this though, a VG powered sandrail is AWESOME, PICS are a MUST! And now the obligatory question; Why a VG, so many better suited engines out there for the task?

[agent4573]

Thanks... I guess. I don't really need advice on tracing wires or anything like that, I was just hoping for info on what I can actually get away with cutting out and still having the engine run. Right now its a completely stock ECU, and I would like it to not throw a CEL when I start it up. Eventually I'll have to chip it and get it tuned as the intake/exhaust should be enough to throw off the stock ECU.

I picked the VG for two reasons: 1. It lends itself to being turbocharged rather easily, which is the plan eventually. 2. My buddy had one laying around and wanted 500 bucks for the motor, ECU, wiring harness, etc. So it was cheap and available.

Trying to add pictures but I can't figure out how to attach it to the post and since I'm at work and stuck on IE7, I can't get to my imgur account to host them offsite. You'll have to wait on pictures.

[NolimitZ32]

Oh ok, in that case AFAI remember the only emissions component that will throw a CEL is the EGR. The IACV-AAC & IACV-FICD are needed for your engine to run properly, they are in charge of idle air control and air balance under load. Not really sure about the rest.

[agent4573]

Well I have none of that stuff, so its not really an option to install it. Guess I'll just have to see if the stock ECU can handle it. If not, theres a guy selling an older Haltech for 500 bucks, I'll have to go the aftermarket route. Will the CEL from the EGR put the computer in "limp home" mode or will it still be usable? I know most of the JWT aftermarket chips delete the EGR function, would that also be a possible route to take to get rid of the CEL?

[NolimitZ32]

THe AICV/AAC/FICD should be attached to the back of the intake manifold. I'm not even sure you can run the engine properly without them. The EGR will throw a CEL but shouldn't cause limp mode, you could get a chip that deletes the EGR (I have mine deleted with a EPROM to match). I think your problem with limp mode will be the other stuff you're missing. I couldn't even beggin to speculate as I've never tried to run mine with the all the air valves unplugged.

[twinturbozxtacy]

id just like to say i run my z w/o the iac etc... runs fine, just stumbles a little on post pull let offs. a tap of the gas pedal keeps her from dying. it is a PITA but was cheaper than the new iac components, will i get them in the near future, yeah, ,my car is a dd driver so its a must. but if you want i have the balance tube, with the iac and all the extra crap taken off and welded closed. just the small vac t for the fpr left on it... id trade for a stock tt balance tube if interested.

[agent4573]

I would trade, but I have an NA balance tube. Thanks for the offer. Appreciate the insite into the drivability though. Its nice to know I can get it running decent.