Kill switch how-to

[RobertSmalls]

I'm going to disagree with you on the emissions merits of an ignition cut over a fuel injector cut.

The engine is going to turn over only a few times between when you hit the kill switch and when it comes to rest. An injector cut will save a few pulses worth of gas vs. an ignition cut. If you dump those few mg of gas into the exhaust and it doesn't get ignited, then you've created HC emissions. If it does get completely burned on the cat, you've raised the cat temperature a degree or two... but it's going to cool off a few dozen degrees anyway while you coast to a stop and wait for your light to turn green. The cat will get back up to operating temperature soon enough after you take off, no sense in pouring fuel on it to make that happen faster.

My Honda hybrid leaves the factory with auto-stop, wherein the engine comes to rest when it's not needed, and the cat begins to cool down. Yet the car meets with EPA and CARB approval.

As far as FI PW >0 during DFCO, huh. That's a head-scratcher. Are you sure? It kind of makes me want to measure it with a multimeter, not a scantool. The Scangauge reports that my Subaru uses 0.04gal/hr at 0rpm, which is clearly not the case.

[Piwoslaw]

Originally Posted by jtgh

The is not a green endevor because you are lettting the CATconv. cool off and that makes nasty startups.
Cold cat = smog.

As Rob noticed, many new cars have auto start-stop. My turbodiesel has insulation all around the cat, so killing the engine for 30 seconds at a red light won't cool it too much.

On the other hand, even without engine-off my hypermiling has brought the engine temps even lower than last year, and this is with a grille block. I guess this means I've increased efficiency?

[jtgh]

Originally Posted by RobertSmalls

I'm going to disagree with you on the emissions merits of an ignition cut over a fuel injector cut.
(gee, that's a surprise)
sure , but who said best case, engineering is about worst case.
Imagine coasting down that long grade, I80 East to the Reno Area.
I never once said factory car designed for fuel cut , were wrong or dirty.
Gee,they have a special cat , to it lights back off fast (low mass element and a short path to the exh. ports .)
this is a modding forum. (again worst case , and Emission mods are illegal or did you forget to notice the rules in the EPA, regs. i can quote them,but why, this is nothing, new. Just do your own search for the word "modification")


The engine is going to turn over only a few times between when you hit the kill switch and when it comes to rest. An injector cut will save a few pulses worth of gas vs. an ignition cut.

If you dump those few mg of gas into the exhaust and it doesn't get ignited, then you've created HC emissions. If it does get completely burned on the cat, you've raised the cat temperature a degree or two... but it's going to cool off a few dozen degrees anyway while you coast to a stop and wait for your light to turn green. The cat will get back up to operating temperature soon enough after you take off, no sense in pouring fuel on it to make that happen faster. Sure, why not.?

My Honda hybrid leaves the factory with auto-stop, wherein the engine comes to rest when it's not needed, and the cat begins to cool down. Yet the car meets with EPA and CARB approval. ( imagine that )

As far as FI PW >0 during DFCO, huh. That's a head-scratcher. Are you sure? It kind of makes me want to measure it with a multimeter, not a scantool. The Scangauge reports that my Subaru uses 0.04gal/hr at 0rpm, which is clearly not the case.

Depends on what car , what year, your experience is limited to just a few cars,and you need to read more about ScanGuage.


you dont understand the Scanguage. Sorry, (read the calibration white papers"
in most cases, it uses , Airflow from the MAF AND THEN reverses the calculation back to the injector PW.
with poor accuracy at all times and horrible accuracy at low fuel rates !!!

It says that in their write ups.(ScanGuage)
many cars with obd2 do not have injector , PW logged.
what your car OBD2 ,does varies by brand and year.

Some cars , cut full totally. DFCO
some keep the CAT , tickled with fuel. (year and models vary)
I have a 91 TBI car, that cuts 100%

to find out the truth takes a scope. no better way.
attached to the injector and drive.
first print out you Injector Dead-time spec, and the flow characteristics.

this action prevents you from getting confused by all the layers for software/firmware.

hope that bods well with your Physics degree.

look up too , how non linear the injector is at low PW just after deadtime.
read up on that.
and most cheap Multimeter do not measure PW accurately ,there sample rates are way too slow.
Get GMM /DSO or real scope and look at accurate measurements.

the whole point of SCANGUAGE is to find the sweet spots for MPG
accuracy is not even close.
It is not an instrument nor is it traceable to the NIST.
However it does a great job at finding the sweet spot in all gears.!

I use Palmer software and it too suffers from the same issues.
cheers.

[RobertSmalls]

It's a Mechanical Engineering degree and an ASE certification; get it straight, troll.

I stand behind my post.

[jtgh]

so why degenerate to name calling. ( and the peeing contest)

its only opinion, please try to keep that in mind.
commentary,
just because some one doesn't buy into the Scanguage concept 100% dont make him or her a troll.

gee.

[Nerys]

I have not read this entire thread (I WILL though) but have to goto bed and want to get this out their.

what about rigging the switch to the IGNITION WIRES right there in the column? I imagine when you turn the "key" to the on position its "activating" a wire.

can we not interrupt that wire so it would literally be as if we turned off the key this way the car will turn off "as designed" to?

also when I EOC I turn the key off and then turn it back on right away (but not too fast or it restarts :-) this way I can just pop and go. is this bad? ie are my injectors still spraying with key on? (I assume not since its not doing that when the car it sitting off when I start up)

Just Curious! limiting myself to interior wires would be nice and utilizing the existing systems would be nice.

[Piwoslaw]

Originally Posted by Nerys

what about rigging the switch to the IGNITION WIRES right there in the column? I imagine when you turn the "key" to the on position its "activating" a wire.

can we not interrupt that wire so it would literally be as if we turned off the key this way the car will turn off "as designed" to?

As you said, this would be the same as turning the key, or maybe slightly better, since the ignition won't deteriorate and no risk of blocking the steering wheel.

But take a look at the differences between key-offing the engine, and when it stalls. In the first case not only the engine turns off, but also the radio, lights, computer, etc. When you turn the key back to position '1', the computer restarts, which can take 5-10 seconds.

With an engine kill switch, only the engine stops, leaving the lights, computer, etc. on, which is safer when you're rolling.

[Nerys]

hmmm maybe my car is weird then (seriously anything could be going on here) but when I turn my engine off NOTHING turns off but the engine.

I have to turn the key ONE MORE click back from engine off to get "power" to go off. I am driving an xfi so everything except the engine is manually driven or independant of the ECU.

In fact I make it a habit of only going the one click because if I go 2 click the wheel lock is able to engage and the radio resets (pain since it resets the volume to a default point as well and restarts the music from the beginning)

my lights stay on (although now that I think about it TURN SIGNALS disengage till I return key to the on position but lights and what not stay on)

I guess there is more going on in that switch than just on off :-)

I also try to "pop" start since the act of engaging the starter "also" resets the radio.

I guess the ECU does reboot as I get that initial "nag noise" and the dash lights engage.

[jtgh]

why guess, you do know the car has a schematic.?
do you wont one for free so you can stop speculating .

most of what you are saying are wrong, not all.

the key switch my not be clear to you with a schematic.
it can have more than one position.
1: off ( all , , ignition, Coils, ECU, EFI, sensors, all) cept ECU memory. and HL.
2: on, this powers up all the parts. (not on, in #1 above)
3: START, cranks motor and tells ECU you are doing that.

4: some cars have accessory position that powers, just that.
there is distribution drawing.
this shows clearly what is hot all the time and what is not.

if you need this for your car just let me know. free.

Never on purpose , put a momentary (open) switch into your car
that powers on all the electronics , over and over .
this surges the electronics and is very bad for it.

There are exceptions, but in general do not do this unless you can prove it is ok to do so.
ever price an ECU/PCM?

Igitions are simple but in the global view they are complex that is because they are all different. many many kinds there are.
Ford,Chev. Toy,. Nissan, Suz. etc. and generations.

the best way to cut spark and fuel is to cut the Cam sender.
this kills the hall sensor output which is harmless.
on a new car it will set the DTC.

94 metro, the ECU , is very old , and are $200 to $400 exchange.
you kill power to the Distrubutor
and the main relay , fuel pump and a whole chain of stuff.

on a Metro, (inside cab , ok , i get you)
kill the power to the fuel pump, but the pressure may take 3 seconds to drop) and delay.
I am thinking ( know ECU real well , i repair them)
the ECU will go DTC for any cut to any sensor, but Injector (maybe)
cant cut TPS, or any.

yours has DIzzy based Cmp sender (a Cam sender hidden).
it too is monitored by ECU for shorts and opens.

I really would never cut power to the main feed.
not like this. (heavy usage) .

when you restart the ECU must go from Bump start to full closed loop cruise.
id bet it wastes fuel doing that.

this can be proven with a injector log device. (kits here , mpg gauge)


does this help.

study Latch up of semiconductors (google) and how surging is bad.
fyi.

[jtgh]

there are other tricks.

not tried by me but will work , (and can set DTC's or not) (had this fail on many cars)

Kill power to Distributor ( dtc , cmp.failed 42 Dtc but autoclears,CEL)
or
kill power to spark feed back line ( my trick) this will set dtc only in memory and is erased as soon as corrected. ( i think)

this is called the Ignition suppressor on Suz. cars . (not on XFI , sorry)
it is used for the Tacho signal.
so open the techo line and ECU thinks , dead spark, can cuts fuel immediately
the DTC is 41 (loss of spark)

spark feed back is (on my suz)
brown at supressor module
and yel/blue at ecu.

Some DTC only store while ECU has main power.
this is one.
now i will fetch your schem.

this may prove the best solution.
on suzuki's

know your model car first before hacking , they are all diff


your exact schematic is here. get it. XFI
http://kick-fix.com/look/metro/