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nddavis2
06-16-2015, 08:43 PM
I've put a vq35de into my 91 hatch and have decided to tuck the harness. While unraveling the mess of wires I came across this.

http://imagizer.imageshack.us/v2/350x100q90/540/TD7nd7.jpg

On injectors 2, 4, and 6 they all are sharing a common ground which are wired to a ring terminal to be bolted to the engine. All of these also are wired together and back to ignition power on the ecm connector. In this mess is the pictures I've attached which have both the ignition power and ground wires going into it. Can someone explain what the concept is here?

What it would seem to me is that once the ignition voltage reaches this relay, the relay closes then grounding the wire. I need to know is this the correct way to do this, where in the harness this should go in this bank of injectors, and an understanding of why this was in place as it appeared to be added into the harness? This is not how injectors 1, 3, and 5 are wired.

http://imagizer.imageshack.us/v2/350x100q90/908/LlWFt9.jpg
http://imagizer.imageshack.us/v2/350x100q90/909/XPdMfI.jpg

ultimateirving
06-16-2015, 09:53 PM
Your summary sounds about right. The relay grounds the trigger for that injector and it pulses briefly.

OnTheChip
06-17-2015, 07:54 AM
That looks like a coil condenser (capacitor). Look at the end and there should be a symbol for a capacitor -||- and maybe 0.47uF.

nddavis2
06-17-2015, 09:41 AM
Ah crap you're right on the capacitor. Given the typical function of a capacitor to store voltage, would this be due to the long path the signal has to travel on a vq on the harness for the driver side injectors? Wires loop around the front side of the engine then to the injectors on the drivers side which is where this was located. Like an idiot I removed it and didn't take a picture so I'm not sure if it was before the injectors or after. Still confused as to why the ignition signal and ground would be connected for it though.

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OnTheChip
06-17-2015, 10:30 AM
The capacitor gives the high frequency noise a path to ground when the coil is turned off to fire the plug(s) to keep noise (voltage spikes) out of the ECU.

This has nothing to do with the injector circuits. One side (common color wire) of each injector is feed constant 12V (power) from the battery through a fusible link. The other injector wire from each injector (different color for each injector) goes to the ECU, which grounds that wire to turn ON that injector.

nddavis2
06-17-2015, 01:00 PM
Thanks for the response. Makes complete sense. Found the injector diagram in the fsm and it fits exactly how you described.

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