Kill switch accomplished

[getnpsi]

on cars ive installed kill switches and injector cuts, there is no stumble or funny acting. I think cutting spark or fuel happens so fast the computer doesnt "see it." This is different than let's say unplugging sensors, an injector or a spark plug. Doing this lets the engine still run poorly for many revolutions. The other sensors will detect erratic operation, and have time to trigger a check engine light, probably limp mode.

cycling the ignition key during EOC doesnt make the car act funny. installing a switch inline with a key isnt going to change much. I think we are reading way too much into it. i think the argument lies in cutting the fuel when the car is running not the spark.

[thefirebuilds]

Originally Posted by getnpsi

on cars ive installed kill switches and injector cuts, there is no stumble or funny acting. I think cutting spark or fuel happens so fast the computer doesnt "see it." This is different than let's say unplugging sensors, an injector or a spark plug. Doing this lets the engine still run poorly for many revolutions. The other sensors will detect erratic operation, and have time to trigger a check engine light, probably limp mode.

cycling the ignition key during EOC doesnt make the car act funny. installing a switch inline with a key isnt going to change much. I think we are reading way too much into it. i think the argument lies in cutting the fuel when the car is running not the spark.

cutting the ignition with awful radio shack relays can be dangerous considering the amount of amperage.

I have seen a few setups that cut the fuel pump and coil signal with two seperate relays, controlled by one push button switch. I have been thinking about this:

1. depress switch, relay 1 and 2 close, shutting off coil signal and fuel pump pressure.

2. release switch after a few seconds, relays open, allowing coil signal and fuel pump to refire. Fuel pump pressure will return almost immediately. Fuel is not burned or released as long as the engine is not spinning as the engine is closed at this point.

3. Bump start the car by releasing clutch. The vehicle will be off until this point, but the pump will pressurize as it is designed to during pre-ignition. The coil signal will begin firing as the engine rotates.

[bestmapman]

Originally Posted by homeworkhome53

I found a fuse in a box in the engine compartment marked fuel which I jumpered around with an inline fuse and switch which I mounted beside the manual gear shift. Works fine, but I can still hear my fuel pump running when in the off position, so I went back and looked some more and found a relay that is marked fuel pump in the same compartment. I think what I'm killing is the fuel injectors. When I throw the switch the car continues to run for a few moments. Just long enough to take it out of gear before it loses power. The instrument cluster continues to run and the odometer continues to total which is what I was looking for. The lights stay on which was a biggy for night driving.

homeworkhome53

Do you have any pictures of the fuze compartments.

[mikeross]

Originally Posted by thefirebuilds

cutting the ignition with awful radio shack relays can be dangerous considering the amount of amperage.

I have seen a few setups that cut the fuel pump and coil signal with two seperate relays, controlled by one push button switch. I have been thinking about this:

1. depress switch, relay 1 and 2 close, shutting off coil signal and fuel pump pressure.

2. release switch after a few seconds, relays open, allowing coil signal and fuel pump to refire. Fuel pump pressure will return almost immediately. Fuel is not burned or released as long as the engine is not spinning as the engine is closed at this point.

Howcome when I did this the fuel pump pressure did not return immediately to normal? Does this mean that it needs replacement already? Thanks.

[thefirebuilds]

some cars have a thing, i donno what it's called, but it's a fuel resevoir so the pump doesn't have to work as hard. This can go bad. It has a membrane in it that can rot out.

[americasfuture2k]

i have the schematics to my 08 aveo, i can locate a proper cut off point for a kill switch.

the problem with cutting off the fuel pump is that there is still fuel pressure in the lines. that gas will continue to be spat out as long as the injectors are still clicking and untill that line is clear. doing so adds a 2-3 second gap to "prime" the system to get fuel flowing at a proper pressure to get the engine going. too much time wasted with how fast paced life is.

cutting off the injectors is the best idea since no fuel can flow without them having power. but the problem with that is that the ECM (engine control module) is controlling the ground on the injectors. on an OBD-II system, the injectors are being controlled individually at low RPMs. there should be a fuse for the power wires to the injectors. that would be the right point to cut power on/off. not the fuel pump fuse or relay.

my alldayadiy account expired, so i cant look up the schematics till i renew the account. but having a cutoff at a fuse listed as INJ would be the right way to go at this.

this is the fuse you want to cut power off to.


cutting off power to the fuse labled FUEL is bad juju. thats the same as cutting power off to the fuel pump relay. its all bad juju.

[gtkid2002]

Suggestion: Instead of just cutting off or shorting the injectors, wire them up like a "true bypass" guitar effect pedal. DPDT toggle switch and some resistors that are the same Ohm rating as your current ones will work. I have mine set up to kill 2 out of 4 cylinders on my car.

Switch layout will be like this:

--1 --4
---2 ---5
--3 --6

2&5 are center taps. Rewire the injector (+) wire to these. Lets go with one side for now, then wire the second one up. Wire the (+) wire on say injector 3 to pin 2 on the DPDT switch. Run pin 1 back to where the cut wire left off. For pin 3, solder a resistor that matches the injector's Ohm rating in series and have that go into a T splice into the (-) injector lead. Repeat for side two, or hook do the same thing on a DPDT relay and have two of them, then have a momentary pushbutton switch to activate the relays. Viola!

That way the ECU won't freak out, although if you only shut off two cylinders, avoid high rpm. A: It shakes horribly, B: It WILL trip off the ECU, and the Check engine light is baaaad. And as far as I know, something like this should work on just about any Honda, although it'll need to be tweaked with for some I think. Should probably work on other vehicles too.

[tf4624]

Does it work? dont we need to worry about starting the car up again while coasting in a gear vs Neutral and starting it then?

[cfg83]

tf4624 -

Originally Posted by tf4624

Does it work? dont we need to worry about starting the car up again while coasting in a gear vs Neutral and starting it then?

americasfuture2k can "bump start" the car from neutral after he has killed the injectors. If he never puts the car in neutral and restores power to the injectors, it will start right up again. This already exists in cars as DFCO (Deceleration Fuel Cut-Off).

CarloSW2

[americasfuture2k]

As long as the car is in mothion and the drive wheels and when transmission is in gear it can get the engine internals rotating again. as long as power is active in the computer, ICM, and coils the engine will fire up again when fuel is applied. From a dead stop the engines rotating mass internals will need assistance in spinning again. I.E. Using the starter.