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

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!

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 :thumbup:

Here's an Instructable to do both.

RH77

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.

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.

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 :o

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

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 :D
You could always just solder it back together if it doesn't work right? :thumbup:

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)

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 :thumbup:

RH77

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

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). ;)

I'd vote for killing the Injectors over the Ignition. You would be wasting fuel wile the engine died, where as with killing the injectors you are only loosing a little electricity.

But what do I know, I don't have an ignition system.

Toggle Switch ;)

The "manual time delay relay" - adjustable too :D Flip it off to kill, then flip it back on whenever you're ready to restart :D

Didn't someone try this? With poor results... I think it was something about the ECU not having a feedback loop with the injectors other than the O2 sensor(s) and such. Instead of just killing the engine - it killed and threw a CEL... I'll have to search around to find the post again (it may have been on the "other" :rolleyes: forum :p).

I think cutting fuel triggering a CEL would depend on the ECU. Just guessing that the newer the car, the more likely it would be to throw a code.

But if your car is OBDII and you had a scangauge then you could reset the codes yourself anyways.

Tried this. Got in trouble a handful of times forgetting to switch it back on among all the other driving tasks going on early in the learning curve.

I'm not the type of driver I would have predicted would have made that kind of mistake, so I ditched it and opted for a momentary switch pretty quickly.

This is exactly what I'm trying to avoid. I can just picture myself not turning the switch back on and bouncing my forehead off the steering wheel when I try to restart the engine. :(

After doing a little research, all of the push button shift knobs I've found are normally open switches, so I will have to use some sort of relay, or replace the switch in the knob. Personally, I'd rather use a relay. I think this can be done for approx. $50 depending on the price of the push button shift knob. The other option is to install a momentary switch somewhere else and save money, but I really favor the convenience of having the switch where my hand is already.

My biggest problem was the multi-tasking in the early EOC routine. I made the mistake of grinding the starter on a few occasions not realizing that the engine didn't quit (from a high idle or higher RPM kill -- switched back to "ON" too soon and it sputtered back to operation).

The SGII helps, since fits right in the instrument cluster area and instead of focusing high on the dash, the tach is right there.

RH77

Well, you were exactly right. It threw a Crankshaft Position Sensor fault code.

I had the distributor apart, took pix, documented the process, wired it up, and nothing happened :(

Ah, it's all good -- I don't EOC that much anyway, I was hoping it was an easy fix if people needed it.

It wouldn't start with the wire disconnected, but it ran with the switch flipped :confused:

Oh well, I guess the best bet is to cut the injectors and reset it with the SG.

RH77

BTW, how do you know if your cap and rotor are worn? Seems like an easy install...

Why are you goys making this so difficult???

It's pretty simple...you find the wire(s) for the fuel pump that are connected to the ecu...you cut that wire(s)...you put the relay between the fuel pump wire and the ecu...you attach a on-off switch to the relay... and when you want the engine off all you do is turn the switch off and the engine goes off...you want it on then switch it on and and bump start your car or start it..

1. You don't have to mess with turning of the keys...
2. Your odometer keeps on working
3. You get no check engine light
4. you save yourself a headache

This is what I don't like about car modding...you can either make it right or you can make it work with a ****load of problems...

Duh, why didn't I think of that!

Oh, maybe because...

1. It won't immediately kill the engine
2. As the engine dies, you're killing it by running lean, and
3. Then you need to build the pressure back up for the EVAP can.

Have you tried it?

RH77

I'd suspect killing the fuel pump would be more likely to trigger a CEL than killing the injectors (another guess)

How about finding the power for the odometer, and adding a tank circuit?

Do you guys know we have made this WAY to complicated?

1. It does immediatly kill the engine because I have pressed the gas after and there is no noise and the scangauge goes dead...
2. This is not some performance engine where's it's making 600hp and needs to be tuned so it won't run lean...it's not like i'm flooring it to redline and cut the engine. I press in the clutch let the rpms go down to idle and cut the engine.
3. What pressure???

Besides what do you think happens when you park your car and turn the key to the off position??? I do exactly the same thing except I do it while driving...

If hypermiling was easy, everyone would be doing it :p

The trick is, we have a variety of models, years, etc. with the same requirement: Streamlining the process, without CELs.

RH77

I have never gotten a CEL doing this and even if I do get one the scanguage will take care of it...

May work for you...

But I definitely have some sputtering issues sometimes after killing the fuel pump.

Makes sense, kill the pressure in the fuel line and there'll still be some residual pressure in the lines that will have to be released by the injectors. Resulting in injectors firing after the switch is thrown. More so if the gas pedal isn't depressed (engine idling) when the switch is thrown.

1. Perhaps on your engine... mine sure doesn't (ditto my last car) ;) And that's weird you SG goes dead - I'll add that to the list of reasons I'd prefer not to go that route (my SG stays live with spark cut) :p
2. emissions
3. pressure: colloquial for vacuum pressure

When I turn my key off - my ECU cuts fuel and spark, some solenoids close etc...

RH77 got it spot on

I think I may have a solution that will work best for me. I can cut the ignition wire in the steering column, add a 12v10A SPDT relay, and run it to a button switch by the parking brake to activate the relay. I would still prefer a time delay relay to make things easier, but that can come later.

Compaq888, I'm not ignoring your solution, but since I can't reset error codes with a ScanGauge ('95 model year :( ), I would like to avoid the possibility of throwing a code at all. I have also used a fuel cut-off switch on an old truck that could run Gas, or Propane, and it could go for 1.5 blocks before the gas totally ran out. Granted that engine had a carb, and this is FI, and my logical brain does know the difference, my emotional brain wants nothing to do with it. :) I like that you have found a solution that works for you though.

how much is a engine kill going to gain you ??

Killing the engine while coasting is an advanced technique that should only be learned away from traffic, and it's not suitable for every car.

That said, you could expect gains of about 10% if you consistently shut the engine off where you currently let it idle while stopped and when coasting.

wow 10% seams high for just cutting out idle , how about re-start ?
oh i mean rolling idle

See http://metrompg.com/posts/coasting-e...-vs-idling.htm

Restart with the key, if the car's automatic (and if the transmission is the type that won't be damaged by engine-off coasting). Clutch start if it's a manual transmission.

Again, this is not something I'd recommend for every driver or car. Safety & durability issues. Buyer beware.

if i was to add the kill button i'd add a start button to the system to ,,or a momentary (sp) toggle/rocker switch

I like the way you think, stealth econ, less raised eyebrows.

The shut down isn't too awful, it's the starts that kill it for me.

But I also believe the dash shut-off isn't all that good, not so much because we don't have gauges (maybe that too) but electronically speaking.
And, less power fluctuations wouldn't be harmful.

Interrupting the crank sensor is not a good way to go. Some cars, like mine, have both crank and cam sensors that are somewhat redundant, but are also used to make sure the crank and cam are in sync. If you interrupt the crank sensor, the engine will continue running on the cam sensor and will complain about the crank sensor. If you interrupt the cam sensor, the engine will run on wasted spark, revert to batch injection mode and will complain about this, but it will keep running. Plus, you don't want to set a CEL if you don't have to.

it would throw a code

I actually meant to other people that drive my car, sorry for the confusion. I'd be happy to advertise to other traffic what my MPG is. I even intend to put stickers on my rear wheel skirts showing the improvement in mileage they are responsible for.

As for the switch (back to the topic), I played around a bit with the steering column, and am pretty sure I can splice the relay inline with the main ignition wire, so as far as the engine is concerned it would be just like turning the key off, but the rest of the dash (gauges, lights, etc.) wouldn't be affected at all. I'll have to review the schematics a bit more to know for sure, then take a trip to the electronics store.

Full Disclosure
 

Regarding the fuel pump cutoff.

I know I argued against it, but in the essence of "Full Disclosure", I had an interesting experience.

I replaced a fuel filter on a '95 Merc Mystique last weekend -- the process to relieve the fuel pressure in the line was to pull the fuel pump fuse and start the car until it stalled.

Much to my surprise, the car immediately stalled within 2-3 seconds.

(meanwhile, replaced the filter and the fuse)

Turned the key to on, heard the buzz of the pump for a second or 2, and the car started right up.

Pre-OBDII and no codes.

I haven't tried it on the 'Teg -- should there be a concern with the injectors trying to pump diminishing fuel supply (or lean-issues)?

Side Note: For those interested in buying a used car...

I don't know what team of "experts" designed the Contour/Mystique Zetec 4-cylinder. When rigorously maintained, it's an efficient engine (easy to attain 30 MPG). There's the kicker -- rigorous! The buildup of carbon into the EGR is a big problem. It also gunks up the idle air control valve and there's no idle screw -- all ECU controlled. Most are running around rattling teeth at the 450 RPM idle. Replacing the oil filter is a huge pain. The Peterbilt-sized filter barely squeezes through the suspension parts. The recommendation is to remove the right-front wheel to get to it easily. :confused: What if you use ramps? This (1995) model year had 7 recalls and terrible wiring. There are some wires to the fans with cracked insulation, exposing bare wire (heat/humidity was the culprit). '96-onward fixed most of the problems.

RH77

Or U could kill the injectors
 

If you tie into that and kill the power to the injectors you effectively kill the engine immediately with no fuel loss.
It would be the same as if you had pulled the injector connector loose.
I am not sure whether or not it would set a code on your engine, but it won't set a code on the '95 & older Metros:).(at least not on mine)
Anyway, just a thought on a different yet similar way to kill the engine for EOC.
TTFN
S.

FI cutoff produces something like a misfire code. Easy to reset with the SG.

Still searching for that CEL-free cutoff...

RH77