Kill switch for 88-95 Honda Civic/CRX/DelSol

[Christ]

In my car, you can pull the hazard fuse and still start the car, and drive it around. It's just that 2 things happen:

1. You won't be able to use your Hazard lights... (duh, you pulled the fuse)
2. The CEL will light up while the ignition is on, but as soon as you shut it off, it will clear the code.

Pulling the hazard fuse essentially allows the ECU to delete it's running memory (when powered down) and re-upload the memory (on next power up) from the solid-state program (the one that never changes) in the ROM. It will not prevent the ECU from actually throwing a code though.

Switching the hazard fuse in my car is a quick way to reset it while tuning.. every time you do something to the car, it's a pretty good idea to reset it... as with any other ECU controlled vehicle.

[some_other_dave]

Originally Posted by Christ

Other than that, I don't like cutting fuel first, as this can put you in a lean situation (especially a fuel-cut rev limiter).

A couple of seconds of lean operation isn't enough to damage the engine, IMHO. It takes significantly more than that to heat up the pistons/chambers enough to really matter, and if you're using it as a kill mechanism the engine will stop running and stop heating up very quickly.

I prefer the idea of cutting the injector power because once you do, the only fuel going in is whatever is already in the manifold--so you'll only get a couple of revs more with any fuel at all, really.

My "other car" has a spark-cut rev limiter, and if you ride the limiter you can load up the exhaust with fuel and then ignite it in the header. Thank heaven for low-restriction mufflers....

-soD

[Christ]

Originally Posted by some_other_dave

A couple of seconds of lean operation isn't enough to damage the engine, IMHO. It takes significantly more than that to heat up the pistons/chambers enough to really matter, and if you're using it as a kill mechanism the engine will stop running and stop heating up very quickly.

I prefer the idea of cutting the injector power because once you do, the only fuel going in is whatever is already in the manifold--so you'll only get a couple of revs more with any fuel at all, really.

My "other car" has a spark-cut rev limiter, and if you ride the limiter you can load up the exhaust with fuel and then ignite it in the header. Thank heaven for low-restriction mufflers....

-soD

We (friends and I) used to intentionally cut spark to engines while they were at high RPM/load, then cut the spark back on at full throttle as they were about to stall...

think: flame thrower kit.

[lunarhighway]

i've had a look if i could addapt this to my car.

i've been looking over my fuses and found a fuse labeled 'FI' when i pull it the starter will turn but the car won't start, if i pull it when it's running it'll run for a second and than dies.... al electric systems and lights keep running as mormal
reinsert the fuse, nothing happenes, and it can start as normal....

sounds like this is the fuelpump and yes, somewhere on the web i found this fuse is for:

Fuel pump
Control unit
anti-theft warning system
Immobiliser (radio controlled)


i have an alarm but no immobiliser so i don't have to worry about that, but what about the controle unit part? other fuses are also labeled "Control unit" amonst other things according to the same source so what does this stand for? as everything else keeps running as well i don't think it cuts out the ecu

would there be a downside to basically wireing a switch in series with this relay to act as a stop switch?
as opel is GM perhaps american early 90's GM car use the same layout

if it does just interrupt the fuelpump that might be my best bet for a simple safe start-stop switch... my only problem with interrupting the fuel pump is that it might prevent smooth (bump) restarts
however i would not have to cut any factory wires so the system could be fully non intruseive... there does not seem to be a fuse for the injectors i can find, sofar an injector cutoff is not an easy option.

[Christ]

control unit might have something to do with an ECM, if you have one. You'd have to get a FSM and trace the fuse location.

An injector cut off is not an easy option, by any means. It happens to work fastest though. Cutting the fuel pump is an OK way to do it, but you should not (from what I've been told) leave the ignition system on, as it could cause damage, according to some FSM's and techs alike.

[lunarhighway]

but you should not (from what I've been told) leave the ignition system on, as it could cause damage, according to some FSM's and techs alike.

i'm not sure im with you here, i mean i can see it's not a ideal situation where the sparks keep fireing when there's no fuel going to the engine as they might be cooled by the fuel.
but how exactly whould leaving the iginion on be bad?

if i where to cut out the fuelpump i'd press down the clutch, pop it in neutral and while doing that, cut out the pump long enough to starve the engine...
than i'd eoc on, and when it's time to restart the engine depending on the speed, either start with the electric starter possibly with a start switch next to the stop swith, or bumpstart
(which could be a problem as i imagine there's no fuel going to the engine immediately...)

so only when the engine was "starveing" it would be running for a second or so with little or no fuel in it... but than it would stop turning and the spark plugs would stop fireing... this situation would be fairly identical to switching the ignition to on, prior to starting the engine no? or would the ecu interpred things different and perhaps keep fireing the spark plug of the cilinder that was about the enter it's power stroke?...

what's an ECM? en electronic controle module? but for what?... could this be some sort of fuel pump feedback for the ecu perhaps, a simple on off thing that telld the ecu the pumps running or not? it might make sence to give it the same fuese so that when that fuse goes the feeback goes too and the ecu know there's something wrong?

i have the wireing diagrams for the car, but they're a little over my head... i night be able to isolate the fuse though and see what it's connected to...

[Clev]

Originally Posted by lunarhighway

i'm not sure im with you here, i mean i can see it's not a ideal situation where the sparks keep fireing when there's no fuel going to the engine as they might be cooled by the fuel.
but how exactly whould leaving the iginion on be bad?

I think it would be okay. Some vehicles require special handholding to run with a sparkplug removed (i.e. the spark plug needs to be grounded to the body or whatever), but I don't think that matters if everything is installed and firing as normal. The only issue I could see is that the fuel injectors and fuel rail are cooled by the fuel, so you could get some overheating, but for the two or three minutes, max, that you would have no fuel flowing, I imagine it would be okay.

I wouldn't switch off the ECU if possible; I doubt it's designed to handle being switched on and off dozens of times a day, and it's one of the most expensive bits in the car. Somebody mentioned interrupting the camshaft sensor in OBD2 cars; if yours is so equipped, you might try that. That interrupts both fuel and spark.

[lunarhighway]

i don't think the ecu cuts out as all the dash lights seem to respond normal and the car attempts to start...

i've discovered another interesting thing... i knew my car had deceleration injector cutoff but now i foud the ecu pin layout one pin 50 has this description

TC input signal, ignition injection cutoff

if this is a on/off signal perhaps i could have the ecu cut out the ejectors factory style.... that would be pretty cool

[Christ]

leaving the ignition system powered on without a way to discharge is harmful to your ignition system... your ignition coil is essentially a 12v->30-60kV capacitor <(--- what I meant by that.

Again, I don't know if it's damaging or not, but I dont do it either.

The '93 lumina is OBD-1 still, so no go on the cam sensor, I'm pretty sure.

If you have a COP ignition system, you can cut the power to the signal wire for the crank trigger. (Coil on plug, coil per plug) There will be a sensor on your crank somewhere that has magnets on it.. it will also have a signal and circuit wire, you can interrupt that signal to cut spark.

Do not confuse this with the CKP (Crank position sensor) as the CKP isn't necessary to run the car, just to make it run correctly.

[jomelmaldonado]

Hello everyone, I've been reading this post since and recently made my first kill switch for EOC mode. I have a 1998 Suzuki Swift 4 cylinder with manual transmission.

The parts I used:
5 contact relay, Single Pole, Double Throw or SPDT (40 amps)
Relay receptacle
Momentary push button switch (normally open)
Wire/Cable
Soldering Gun
Insulating tape

I used the SPDT relay, the 30 and 87a terminals to interrupt the current flowing to the positive side of both coil packs, since my engine has 2 coil pack, but with a common positive wire.

The terminal 85 was connected to the positive side of the ignition, but source, not the coil side, but the rest of the harness side.

Terminal 86 was connected to ground via the momentary push button switch. So I only had to lead one wire through the grommet of the fire wall and in to the cabin. And its ground, so in any case of a wire scuffing, the worst case scenario, it will not catch fire, it will only turn off the engine.

When I want to kill the engine, I throw it to neutral, then I push the button until engine looses all the RPM's. Since it's a momentary switch, ass soon I release it, it will be ready to start with the starter or with the inertia of the car and it's manual transmission.

The fuel pump will deactivate after about 5 seconds of no RPM detection. Also, there is no fuel injector, nor any ignition coil activity since there is no RPM detected. Everything is stand by for the next RPM movement. Still in test mode, but it's working fine. My scanguage remain on, so I don't loose the current trip memory.

The next thing I want to do is to make a circuit that automatically re-starts the engine when I press down the clutch down. But only if the engine is off. I can to this with an Op-Amp comparator and the Charging light. Since the light goes off when alternator is charging, and alternator start charging about the same time engine is on steady. I will be doing this in the near future, and will keep you informed.

Another idea is to use a hybrid alternator, those used on GM's Chevrolet Malibu and Saturn Aura engines. They use an Ecotec 2.4 L and they start the engine with a belt driven alternator/starter (BAS). If I find one of those, I could even make my car a mild hybrid, better than the pathetic 24/32 MPG those Malibu's and Saturn's currently achieve, since I will be using a much smaller 1.3 L engine. What do you people think about this idea. Would it be feasible?