Stealthy injector kill switch, 6th Generation Civic

[California98Civic]

EDIT: the switch build write-up is in post #3

I'm about ready to install my kill switch for my 1998 manual trans Civic DX, but I have a question. In the picture attached, do you think the switch I bought will serve (after I remove the door jamb plate)? I am emulating this design plan: http://ecomodder.com/forum/showthrea...tml#post157489 ...but with a twist...

What I plan to do is insert the switch into the OEM (auto trans) shifter I bought (also in the picture). The 6th Gen auto had that button on the faux stick-shifter to prevent accidental selecting of reverse or park ... I'm going to slip my switch into the shifter knob. The switch from pepboys and the shifter's button housing are almost perfectly matched... the switch should work, yes? No?

[brucepick]

My kill switch is not stealthy. It's a flip switch about an inch long, amber color, that originally ran a set of fog lamps that I removed after buying the car. It's on the left side of the dash. Down for "run", up for "off", in my case.

I can't tell you from the pic whether it will work or not. I'm sure if you run the right wires to it and break the circuit at the right point, it will do the job.

I can tell you this though. You need about 2-3 seconds of time when the injectors are shut off, for the engine to come to a stop. Then I want to restore the injector circuit. If your new switch requires holding it down to disable the circuit, you'll be holding it down for a duration.

My setup gives a yellow check engine light (CEL) as soon as I cut the injector power. So as soon as the red dash lights and the tach indicate the engine is stopped, I flip the switch back on. That way the computer is happy and the CEL goes away. And as soon as I want to bump start it, the injectors are already switched on. They "spit" no fuel while its stalled of course as the rpm's are zero.

Good luck with it!!

[California98Civic]

For the FI kill-switch build, a friend convinced me of the value of this design for a fifth generation civic, which interrupts the ground to the injector relay. THE ADVANTAGE of this design is that there will not be a large electrical current running through the switch and its leads, which run along the metal shifter rod.

NOTE: For the sixth generation civics (1996-2000) the fuel injector relay was moved to the passenger side dash, behind the glove box, beside the door. In the fifth generation civics (92-95) this relay was beside the fuse box under the dash on the driver's side. It is harder to get at in the sixth gen arrangement. Here's a pic of the FI-relay as installed behind the glovebox:



Here is what you need for this kill switch:

1 - A non-lighting interrupter switch (push to break the circuit).
2 - 5+ feet of 18 gauge wire (black preferably).
3 - At least four butt-splice fittings.
4 - An OEM Sixth Gen auto trans gear selector.
5 - TOOLS: phillips head screw driver, wire clippers, 10mm socket.

Here is the basics of what you do (see pics):

1 - Remove the glove box
2 - Identify the injector relay
3 - Remove side panel to get at 10mm bolt securing relay
4 - Cut back conduit and clip black ground wire one inch from plug
5 - Strip ground wires both ends and attach butt-splices
6 - Attach your wire to the splices to make a long ground wire extension.
7 - Attach wires to switch (we had to solder, but you may find easier switches) and insert wires and switch into shifter knob.
8 - Securely mount the shifter knob to the shifter, wires running on the inside, down the shifter and under the pleather decorative thing.
9 - Attach switch wires to extended ground wires using a second pair of butt-splicers.

PS: in the final install, I went with a black button. Stealthier. That's why the color changes in the pics.

PPS: Special thanks to my friend BG.

[brucepick]

Nicely done.
I'm curious whether your setup works the way mine does - do you get a yellow check engine light that goes out a few seconds after you let go of the cutoff button?

I broke the continuity of a wire under the hood, near the driver's side hood hinge. I was never able to trace it completely to the injector area, thus I'm interested to know if yours behaves the same. Tomorrow I'll check the color of my wire and edit this post with the info.

[California98Civic]

Originally Posted by brucepick

Nicely done.
I'm curious whether your setup works the way mine does - do you get a yellow check engine light that goes out a few seconds after you let go of the cutoff button?

The check engine light goes on immediately, I wait a beat, and the second the battery and oil lights go on (sometimes battery first) I re-engage the FI ground. It is very tiddy. Generally the ECU does not cut-off and the UG stays functional, though the stock speedometer cuts off temporarily [EDIT: the speedo stays on]. The check engine light turns off when I re-engage the ground, but the oil and battery lights stay on, of course, until I bump start the engine.

Originally Posted by brucepick

I broke the continuity of a wire under the hood, near the driver's side hood hinge. I was never able to trace it completely to the injector area, thus I'm interested to know if yours behaves the same. Tomorrow I'll check the color of my wire and edit this post with the info.

I see I forgot to add the actual shot of the FI-relay as installed behind the glove box. I'll figure out a way to edit post and add it now. Sounds to me like your and mine behave the same way.

[Arragonis]

Thanks - good write up, have you thought about adding it to the Wiki or how to section ?

[California98Civic]

Originally Posted by Arragonis

Thanks - good write up, have you thought about adding it to the Wiki or how to section ?

Good suggestion. Just did it now. Thanks. I love the switch. Life is easier, and it aids the safety of the technique because I have fewer motions to make, and need never change my line of sight. I can see the indicator lights change while watching the road. Also, when I was keying it, I would lose blinker function. Not anymore.

[PaleMelanesian]

I'm not quite following the actual wiring details here. Are you breaking the black (ground?) wire or are you grounding out something?

[brucepick]

Originally Posted by PaleMelanesian

I'm not quite following the actual wiring details here. Are you breaking the black (ground?) wire or are you grounding out something?

I just did a careful read of the link given in this thread's first post.
Both methods use the new switch to temporarily sever the black (ground) wire that goes to the injector relay.

You sever the black wire and insert the switch into the cut location. California98Civic specifies an interrupter switch, also called "NC" type. Normally Closed. Which means that it is normally "on" when not pressing the button.

Here's a bit more electrical detail, if you would like to understand what's happening.

The relay has a "switched" side (or power side) and a "control" side. Two wires for each side, total of four wires. The switched side has a powered lead going in, a small internal switch, and the lead going out to the injectors. The internal switch controls whether that power is sent out to the injectors.

The relay's control side has its own powered lead going in, which powers a small coil that activates the switch. And there's a ground going out from the coil that completes the coil circuit. As long as there is power to the coil and a ground path out of the coil, the internal switch is closed ("on"), and the relay's switched side sends the switched power out to the injectors.

By temporarily severing the ground wire you disable the relay's internal switch, and it sends out no current from the switched side.

Normally the car's computer controls the relay to enable or disable the injectors. This modification just adds one more place from where the relay's status can be controlled. I can't tell from here whether the computer switches the power to the relay's control side on and off, or whether it severs the control side's ground, basically like this mod does. Either way would disable the small coil, which ultimately means no power going out to the injectors.

The injectors themselves receive constant power as supplied via this relay. They are controlled on their ground side. Each injector has its own ground wire going to the computer. The individual grounds are completed by the computer for small fractions of a second at a time. Each injector will squirt fuel only when its individual ground path is completed by the computer.

Sorry for all the wordage. I'm the only one awake in the house and it's too early to do other things.

[PaleMelanesian]

That tells me what I need to know. Thanks. It's a simple-ish mod, I may have to try it in the near future.

Oooh... Does it leave the fuel system pressured up? That's a problem on my car when it gets low - I have to cycle the ignition several times, to run the fuel pump, to get the pressure high enough to actually start the engine. I'd guess this would help with that issue by not running down the pressure.