Stealthy injector kill switch, 6th Generation Civic

[baldlobo]

if you have a factory anti-theft device(required by 2000 in canada), there is at least one fuse in use by that system, rather than cutting wires and getting check engine lights; my 1999 jeep tj has a fuse that can be used to cut both ignition and injectors.

[benphyr]

Baldlobo,

Do you mean that you can pull the fuse for the anti-theft, route that circuit directly from the fuse (fused elsewhere in the same loop of course), and run your wires to your kill-switch from there? That is, replacing the anti-theft fuse with a a circuit that progresses from beginning fuse terminal, to fuse, to kill-switch, back to other fuse terminal?

Sounds awfully simple, and is killing spark and fuel at the same time just like keying off.

How would I go about finding which fuse? Any suggestions on what they would call it on a 2005 Civic?

Cheers,
Benphyr.

[baldlobo]

ok second time around typing this; first get yourself a civic service manual(it can be googled) trace the wiring diagrams. bad news is your civic's immobilizer only shuts off the fuel pump from what i read; that and honda grouped the wiring so it is hard to just pull one fuse. i can give you hints, i'd look at fuses for the ignition coils and fuel pump under the dash.

[steffen707]

Originally Posted by California98Civic

I don't KNOW the answer, but I have run the tank down to its last two gallons probably four times since the mod, maybe more, since this mod. I have never had to do what you describe, suggesting I may have better pressure in the fuel system.



This is exactly the sort of idea I had. My goal was a shifter that was stock in appearance, so I got a stock 1998 Civic auto shifter knob! Fits the interior styling perfectly.

Does the auto shifter knob screw onto the manual shifter like the manual knob does? That would be awesome. There's a few junk yards near my house, I know i can find an auto shifter there.

[steffen707]

There may be a problem with this method. I know with older EF civic/crx 88-91 the relays also control the fuel pump. This might account for the hesitations that people have been experiencing. Read this webpage for a great detailed explanation.
How the Main Relay works

Not positive it is the same for 96-00 civic EK body styles, but could be.

[steffen707]

From the link I provided above, I think if we just inturrupt the 3rd wire that goes to the ecu and injectors the fuel pump may stay on, but this probably will cause check engine lights.

I'm not positive that the ground operates both of the relays in the main relay, the engine schematics are a bit confusing at times.

I suppose it would be easy to test, just check and see if the fuel pump still has power when you disable this switch. Or hold the switch down when you turn the ignition key on, do you hear the pump turn on? Then you would know.

Can you test this? Maybe i'm jumping to conclusions where its not needed.

[steffen707]

Upon further investigating it appears that the main relay also provides power to the EACV, which aids in controlling the idle of the car. Disabling wire 3 of the link above would cut power to the injector as well as power to the eacv, but may let the pump still have power.

[steffen707]

FYI, i tried turning the car to ig1 7 times, each time disconnecting one of the 7 pgmfi main relay wires before turning the key. On all but 1 the fuel pump never turned on. The one wire that could be disconnected and the fuel pump still turned on was the blue wire, #6 on the honda shop manual that goes to the ST switch.

If you disconnected any one of the other 6 wires, the fuel pump wouldn't turn on.

You may be thinking well what about if the car is already started and running and you disconnect one of those wires (via a switch), well I plan to test that on Thursday, while having my multimeter connected to the fuel pump and will report back the results.

[WD40]

It definitely kills the pump in my VX.
I tried key on to hear the fuel pump with and without the kill switch.

[steffen707]

I stopped by the store to get a couple connectors to be able to make jumper wires from the relay to the relay harness so I can test disconnecting each of these wires, one at a time while the engine is running, and with my multimeter hooked up to the fuel pump. I might have results tonight because i get off work around 5pm.

I did read there is a check valve inside the fuel pump. Honda manual for obd1 cars 11-114 says, "When the engine stops, the pump stops automatically. However, a check valve closes by spring action to retain the residual pressure in the line, helping the engine to restart more easily.

So even if you use the "ground switch method described on page 1" and the pump gets shut off, the check valve should retain the pressure for the seconds that you have it off on gliding. If you are having stumbling or hesitation issues when you bump start the car from an EOC I think you might have a weak check valve (just a guess). Hopefully I can find one of these wires to disconnect to shut off the injectors and not the pump.