Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Civic engine kill WITHOUT interrupting ECU

firehawk618 · 03-26-2015, 10:56 PM

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.

03-26-2015, 10:56 PM	#1 (permalink)
firehawk618 EcoModding Apprentice Join Date: Oct 2014 Location: Marysville, wa Posts: 221 97 Civic HX sedan VX trans - '98 Honda Civic LX + HX + VX 90 day: 41.9 mpg (US) Thanks: 23 Thanked 42 Times in 24 Posts	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. __________________ 1998 LX with a full HX swap + VX transaxle.