I'm curious about a "nitrous" style engine kill button

[Volones]

In order to facilitate EOC without interrupting speedometer/odometer functionality, I would like to install a push button switch that cut the power to the distributor/coil so the engine would just die. I remember someone doing this, but couldn't find the thread in a search.

I think it would be easiest to do with:
1 - push button shift knob (sold most often to the nitrous injecting crowd)
1 - relay that can handle the voltage/current that controls the ignition circuit
assorted wires and connectors to connect said parts

I found a knob that has a cover on the top of the shifter with a button under it which I think would be best since my wife would freak out if she accidentally turned the engine off while driving. If that knob can be wired to control the relay to interrupt the ignition system, it should be a pretty clean looking mod.

Can someone please advise me about the best location to put a relay to interrupt the ignition system, and what size of relay would be necessary? I would use a relay if the voltage/current was too high to run through a little push button switch, but if not, then the relay would be unnecessary and I could just splice the switch into the ignition wiring and push the button to interrupt the circuit (with a normally closed button switch of course). I don't want a flip-type switch as I would forget to switch it back on.

Thanks for your help in advance,
Vol!

[RH77]

IIRC, an easier option has been to kill power to the injectors, since the ignition system has a much higher amperage to deal with. That way, you wont have to hack the steering column or find a super-duty relay.

The downside is a Check Engine Light for cylinder #x misfire or similar.

If you want the full package, get a push-button start

Here's an Instructable to do both.

RH77

[Volones]

I read that, but he's chopping into the main fuse, and I'd like to keep the speedo/odo working uninterruptedly. Right now, I lose all gauges when I switch off the engine for 2-3 seconds. He does another kill switch, but that one just kills the fuel pump which isn't a viable option for me either.

My desire is to keep my changes as "invisible" to another driver as possible.

Thanks though, the ignition current was my chief concern, and the only relay I've found so far that can deal with 80A costs over $100, but I'll keep looking.

[MetroMPG]

If you have a schematic or can find the "coil pickup wire" from your distributor (if you have one - I don't know your engine), that's the wire I spliced into. (I'm the person whose post you read, I think.)

It's not a high voltage wire, it's just a signal wire from the distributor to tell the coil the position of the rotor. Interrupt that signal and the coil stops firing. No engine codes are thrown, and the ECU/gauges stay live.

My kill switch is on the shifter also.

EDIT: on the Suzuki motor, there are only two small wires coming off the distrubutor. They're the wires for the pickup circuit. I don't think it matters which one is spliced into the switch circuit.

[Volones]

That's exactly what I was hoping.
I do have a distributor, so if it's getting a signal from a low power source, I should have no trouble splicing the shift knob wiring right into that.

Thanks so much MetroMPG!!!

[RH77]

Originally Posted by Volones

That's exactly what I was hoping.
I do have a distributor, so if it's getting a signal from a low power source, I should have no trouble splicing the shift knob wiring right into that.

Thanks so much MetroMPG!!!

Bear with my noob-ness on understanding vehicle electronics

My distributor has 3 low-voltage wires:

1. Tach output
2. Feedback to the ECU, and a
3. 12V wire between the Coil and Ignition Control Module

I assume that opening the circuit to the last wire (between the coil and ICM) would do the trick (or would any disruption likely confuse the ECU?)

I don't EOC all that often, but when I do, a kill button would be great -- especially to keep the gauges, signals, and ABS active.

RH77

[AndrewJ]

Rick, It's my understanding that if you disrupt any of the ECU's info about the position of a rotating part (here I mean engine part like crank angle sensor, TDC sensor, rotor sensor, etc) then the ECU is not gonna get "confused" it's just going to, for saftey's sake, default to killing the engine.

The trick is to do it without throwing a code/CEL.

That being said, I think you're on the right track with the +12v-Ignition thing.

I guess the only way to know for sure is to cut the wire
You could always just solder it back together if it doesn't work right?

Let me know if you find something that works.

Your integra's wiring should be pretty much identical to my civic's (and preludes for that matter)

[RH77]

Originally Posted by AndrewJ

Let me know if you find something that works.

Will do. Right now, I'm in Columbus, OH driving an Altima 2.5 CVT -- but back home tomorrow night / late. Friday I'll have some time to test it out.

The plan is to pull the WHT/BLU wire mentioned and see if it starts (and if a CEL is thrown). If it fails to start, then I may be onto something -- then I'll splice into it and test an idle-cut and check for CELs. I still have a switch wired-in from a failed cylinder deactivation test a couple years ago -- so that can act as the test switch.

EDIT: The TDC/CKP/CYP sensor seems to have separate wiring from the shop manual...

Thanks to MetroMPG for the insight into a (potential) CEL free cut

RH77

[dremd]

Does your odometer quit when you turn the key "off"?
If not just switch the 1 Blue wire "ign"

from bulldog security


MODEL YEAR(S)
MX-3 1992 -1996


PART COLOR LOCATION DIAGRAM
12 VOLT CONSTANT BLACK (+) IGNITION SWITCH HARNESS
STARTER BLACK/BLUE (+) IGNITION SWITCH HARNESS
STARTER 2 N/A
IGNITION 1 BLUE (+) IGNITION SWITCH HARNESS
IGNITION 2 N/A
IGNITION 3 N/A
ACCESSORY/HEATER BLOWER 1 BLACK/RED (+) IGNITION SWITCH HARNESS
ACCESSORY/HEATER BLOWER 2 N/A
KEYSENSE N/A
PARKING LIGHTS ( - ) GREEN (-) @ STEERING COLUMN HARNESS
PARKING LIGHTS ( + ) RED/BLACK (+) @ DIMMER SWITCH
POWER LOCK ADD ACTUATOR, See NOTE *1 TO DRIVERS DOOR ONLY, See DIAGRAM 14301_MX-3_CENTERAL LOCKING DIAGRAM JBS UNITS.pdf
POWER UNLOCK ADD ACTUATOR, See NOTE *1 TO DRIVERS DOOR ONLY, See DIAGRAM 14301_MX-3_CENTERAL LOCKING DIAGRAM ALERT SHELBY UNITS.pdf
LOCK MOTOR WIRE N/A
DOOR TRIGGER RED/WHITE (-) @ 3-PIN PLUG, ABOVE FUSES
DOMELIGHT SUPERVISION USE DOOR TRIGGER, Requires Part #775 Relay
TRUNK RELEASE N/A
SLIDING POWER DOOR N/A
HORN GREEN/RED (-) or GREEN/BLACK (-) @ STEERING COLUMN HARNESS
TACH YELLOW/BLUE @ DISTRIBUTOR
WAIT TO START LIGHT N/A
BRAKE GREEN (+) @ SWITCH ABOVE BRAKE PEDAL
FACTORY ALARM DISARM N/A
ANTI-THEFT N/A

[Volones]

Originally Posted by dremd

Does your odometer quit when you turn the key "off"?
If not just switch the 1 Blue wire "ign"

Yep, when I move the key from 'run' to 'off or acc', the speedo and odo stop working. It's what I'm doing now, and only lose 2 seconds so it's not the end of the world, but a push button would be so much easier and would get used much more often. I'm even looking at incorporating a time-delay relay so I don't have to hold the button for those two seconds (more 'user friendly', or if you prefer, lazy).