Civic engine kill WITHOUT interrupting ECU
 

I wanted to throw this out there for you guys.

This SHOULD work on 1996 to 2000 HX's as well as 1996 to 1998 DX, EX, LX, CX's.

The cars listed above are all obdii"a" which is important.

I had been trying to find a way to shut the engine off with a button and took a hard look at the main relay. I actually did it off the main relay but it has a problem.

It does kill the engine BUT it also basically shuts the ecu off to kill the engine which in turn makes your scangauge / ultragauge go dead for that time.

The bigger problem in the HX's is that when the ecu is first powered up it basically prevents you from getting into Leanburn for at least 3 minutes upon powering up. Basically everytime I would kill the engine to coast using the main relay I would also reset the Leanburn timer in the ECU.

What I ended up doing was grabbing the common power wire for all 4 injectors. It's a single wire that's only a couple inches away from the ECU.

If you want to be able to stall your engine without resetting the ecu and making your gauges die for a short time do this.

Just above the ECU, follow the harness. You'll see a brown connector. All that does is serves as a bus bar which serves as a splice to join multiple wires as one.

Unplug the brown connector. It's a loose piece that comes off.

Look at the harness you just unplugged. You'll see a group of yellow / black wires which end up spliced together inside that brown connector.

One of those goes to send 12v+ to all 4 of your injectors.

The way I figured out exactly which wire it was is put a VOM on the yellow / black at the injector *unplug from your injector first* then when on the OHMS setting poke each of those Yellow / black wires until you get zero resistance. That's the one feeding power to your injectors.

Cut that wire, hook up a button of your choice.

I will post a picture of the connector later this evening to help clarify what I am talking about.

Doing it this way you only need to run a couple feet of wire to your switch VS going out the firewall.

Much cleaner and easier IMO.

The best way to gain room to do this is just remove your glove box and right kick panel exposing your ECU.

Any questions feel free to post.

Ok 15 mile test drive and here's the results.

When I was in LB I was able to basically keep my foot on the throttle and press the button causing the car to gradually lose speed. The great news is when I pressed the button again to run the engine it was STILL in LB! I did this several times and it always maintained LB.

This can be very good. I have several places where the car will start to gradually go down hill which results in picking up too much speed. If I lift off the throttle that immediately disables LB. Sometimes it'll come right back when I resume cruising, other times it's like the ECU decides it's penalty time and LB won't come back for miles.

I did find ONE problem though. After doing the above, on a relatively long stretch where I was holding the throttle position and scrubbing speed by disabling the injectors the car threw a CEL. What's really odd is when I turned the injectors back on it was STILL in LB and maintained it the remainder of my test drive.

This proved to me that just because you have a CEL doesn't mean no LB. It's going to depend on what that code is.

The code it threw was a P1508 "IAC Valve Circuit Failure".

I am going to check my diagrams better and see if that wire I am pulling power from feeds the injectors AND the IAC valve.

If so, i'll reconfigure things so the IAC isn't losing +12v and see if the CEL still triggers when doing this.

I will report my findings when I figure it out.

Sure enough, that wire that feeds 4 injectors also provides power to the IAC.

There looks like a simple work around on the junction connector by the oil filter.

I am going to move the IAC 12v+ to the other source there and see what happens.

You could try the injector kill a bunch of us use for our Insights, courtesy of Balto:

http://ecomodder.com/forum/showthrea...tml#post453516

It kills the power right at the injectors, nobody has pulled any CELs using this method

Yeah a fuel pump kill switch is the best idea, a kill switch in my driving scenario would prove arbitrary as I can usually time red lights and there are no stop signs in my commute

Thanks for the link. My thought was to avoid running wires through the firewall. I have a feeling that I can move a single pin at the common connector near the oil filter and solve my problem.

I spliced into the injector wire under the hood as you did and it works quite well, much better than into the pgm-f1 where the voltage drain was too high. However, I've found the kill switch only useful for short trips. Here is a photo of the wire from this thread.

http://i188.photobucket.com/albums/z...k/100_0301.jpg

I went in through the firewall on mine and used a tiny rubber grommet at the hole. On the inside I sealed the tiny hole, so I haven't had any issues.

If you don't want to go through the firewall, you can always route the wire through the door, like I did in my tutorial.

Your fluffy Wolf,
Balto.

Hi, does this also happen when using the ignition to shut the engine off?

Yes.

Do you mean by shutting off the main relay? That's how I have mine, I cut the ground to it on a switch.

What negative does this have, just use more battery power an make the alt work more to charge?

Yes, and yes.

Using the pgm-f1 dropped .05 volts from the battery (with the engine off) each time the relay turned back on. Thus 20 switches dropped the battery from 12.8 to 11.8 volts. Moving the kill switch from the pgm-f1, to the main injector wire shown in the photo above, minimized the voltage drop.

My idea was to not run more wires than necessary.

I fully understand all the other ways of getting this done.

I have used the switch several times today and have learned the following:

If I just press it long enough to stall out the engine then let go it doesn't throw a CEL.

The only way I was able to get a CEL again was to keep the button pressed then let the clutch out in gear for engine braking. There's no need to ever do that because if you need engine braking you might as well just ride out DFCO.

I am going to leave my mod the way it is unless I have issues, which so far so good.

Again, I will get a pic of where I did the wiring. It's all right behind the glove box.

I call the connector the Brown Bus Bar because if you pull it off the harness *taped to it* you'll see what I mean when you look inside it.

Today I moved the IAC power wire off the grey plug under the intake over to the blue plug.

On that blue plug there's a group of Black/Yellow wires. Those are all +12v.

Once I moved the IAC wire there, no more CEL and no wires run through the firewall!

I was able to move the pin without crawling under the car.