erik
12-17-2009, 12:07 PM
What the hell is a FAS switch, you ask? FAS = Forced Auto Stop. Allow me to borrow a definition from www.cleanmpg.com (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=1)
Forced Autostop: A Honda hybrid will AS (Autostop) in various scenario’s although it is very limiting to a given condition. Too high a speed, too cold, not enough SoC (state of Charge), not enough speed since last AS, Defrost or A/C on except for the AH and HCH-II in specific conditions, etc. will not allow AS … Forcing an AS in any vehicle (other then an HSD equipped hybrid), aka Fas , takes these limits out of the equation. Shift to N, let the Tach stabilize, key back to IG-I (shuts down the ICE and electronics), key back to IG-II to reboot the electronics and coast to a stop or pre-determined lower speed depending on conditions. Recover by starting up ICE via key to IG-III, release to IG-II, and engage transmission with a rev match to continue on your way. Pro’s include a very noticeable increase in FE over any short distance trip and is required in a few areas of the US as well as much of Europe, ie. sitting at a stop sign for > 15 seconds or at a stop for > 5 minutes … Con’s include powerless coast, power brake assist is lost after a few uses, power steering is lost although at speed, you do not need it, is illegal in some locales, and possibly both gear reduction starter from excessive ICE starts and pre-mature wear from re-engagements of the transmission at speed.
I realize this is a somewhat extreme measure to take trying to improve fuel economy, and I admit it's not for everyone. However, I'm considering fabricating an FAS switch to take the ignition key out of the process, thereby making it more simple and less distracting. From my research, it appears the most common way of implementing an FAS switch is to interrupt the power to the injectors. Some folks tap into a harness under the hood with a simple SPST momentary switch that is normally closed. By hitting the switch, power is cut to the injectors and the engine dies instantly. Another method involves attaching a switch to the fuel injector relay via spade connectors attached to the same type of SPST momentary switch. To me, this is preferable because no wires are cut AND everything can be returned to stock by simply unplugging the switch and replugging the relay.
To borrow from cleanmpg once again, here is a post by a guy describing the use of the FI relay:
I like your switch! :thumbs_up: I have seen injector power kill switch work just fine!
You could also do the same thing at the Injector relay and avoid cutting any wires.
It would take a little more wire to do it this way, but no need to cut the cars wiring.
Disclaimer:
I cannot recommend modifying your cars wiring. As you may harm yourself or your car. Any modifications always run the risk of voiding all or part of your cars warranty.
With that said, If I was to do a FAS switch I Might do it like this.
Need:
-Normally closed switch / button
-Wire
-Wire connectors / clips
1. Unplug the EFI relay
2. Use wire and clips to jumper the connectors right back down to the socket
3. Install the switch inline on the splice the switch in one of the low voltage jumpers.
Large Relay connectors are power to the injectors. ONE of these is ALWAYS hot. Even when the car is OFF.
Make sure to not touch the HOT wire to any other wires or grounding surfaces.
Jumper them right back down to the socket.
http://www.cleanmpg.com/photos/data/500/relay1.JPG
Small connectors are Low voltage from the ECU used to switch the relay on.
Jumper one of them back down to the socket (either one)
Last connector low voltage connector run from the relay to the switch then back to the socket.
When you press the button the relay switch’s back to off, killing the power to the injectors.
No wire cutting required!
Switch can be disconnected easy. If something goes wrong with the switch simply unplug the jumpers and plug the relay back into the socket.
Switch on low voltage side will allow use of small switch.
Again:
I cannot recommend modifying your cars wiring. As you may harm yourself or your car. Any modifications always run the risk of voiding all or part of your cars warranty.
The relay-based solution looks cleanest to me, but here is my question. Where the hell is the EFI relay on my GE8? :) I've poked around a bit and hit up my buddy Google, but haven't had any luck finding it. I suspect I need some sort of service manual or something to tell me where the darn thing lives. If anyone has any hints or tips, I'm all ears.
Thanks,
Erik
Forced Autostop: A Honda hybrid will AS (Autostop) in various scenario’s although it is very limiting to a given condition. Too high a speed, too cold, not enough SoC (state of Charge), not enough speed since last AS, Defrost or A/C on except for the AH and HCH-II in specific conditions, etc. will not allow AS … Forcing an AS in any vehicle (other then an HSD equipped hybrid), aka Fas , takes these limits out of the equation. Shift to N, let the Tach stabilize, key back to IG-I (shuts down the ICE and electronics), key back to IG-II to reboot the electronics and coast to a stop or pre-determined lower speed depending on conditions. Recover by starting up ICE via key to IG-III, release to IG-II, and engage transmission with a rev match to continue on your way. Pro’s include a very noticeable increase in FE over any short distance trip and is required in a few areas of the US as well as much of Europe, ie. sitting at a stop sign for > 15 seconds or at a stop for > 5 minutes … Con’s include powerless coast, power brake assist is lost after a few uses, power steering is lost although at speed, you do not need it, is illegal in some locales, and possibly both gear reduction starter from excessive ICE starts and pre-mature wear from re-engagements of the transmission at speed.
I realize this is a somewhat extreme measure to take trying to improve fuel economy, and I admit it's not for everyone. However, I'm considering fabricating an FAS switch to take the ignition key out of the process, thereby making it more simple and less distracting. From my research, it appears the most common way of implementing an FAS switch is to interrupt the power to the injectors. Some folks tap into a harness under the hood with a simple SPST momentary switch that is normally closed. By hitting the switch, power is cut to the injectors and the engine dies instantly. Another method involves attaching a switch to the fuel injector relay via spade connectors attached to the same type of SPST momentary switch. To me, this is preferable because no wires are cut AND everything can be returned to stock by simply unplugging the switch and replugging the relay.
To borrow from cleanmpg once again, here is a post by a guy describing the use of the FI relay:
I like your switch! :thumbs_up: I have seen injector power kill switch work just fine!
You could also do the same thing at the Injector relay and avoid cutting any wires.
It would take a little more wire to do it this way, but no need to cut the cars wiring.
Disclaimer:
I cannot recommend modifying your cars wiring. As you may harm yourself or your car. Any modifications always run the risk of voiding all or part of your cars warranty.
With that said, If I was to do a FAS switch I Might do it like this.
Need:
-Normally closed switch / button
-Wire
-Wire connectors / clips
1. Unplug the EFI relay
2. Use wire and clips to jumper the connectors right back down to the socket
3. Install the switch inline on the splice the switch in one of the low voltage jumpers.
Large Relay connectors are power to the injectors. ONE of these is ALWAYS hot. Even when the car is OFF.
Make sure to not touch the HOT wire to any other wires or grounding surfaces.
Jumper them right back down to the socket.
http://www.cleanmpg.com/photos/data/500/relay1.JPG
Small connectors are Low voltage from the ECU used to switch the relay on.
Jumper one of them back down to the socket (either one)
Last connector low voltage connector run from the relay to the switch then back to the socket.
When you press the button the relay switch’s back to off, killing the power to the injectors.
No wire cutting required!
Switch can be disconnected easy. If something goes wrong with the switch simply unplug the jumpers and plug the relay back into the socket.
Switch on low voltage side will allow use of small switch.
Again:
I cannot recommend modifying your cars wiring. As you may harm yourself or your car. Any modifications always run the risk of voiding all or part of your cars warranty.
The relay-based solution looks cleanest to me, but here is my question. Where the hell is the EFI relay on my GE8? :) I've poked around a bit and hit up my buddy Google, but haven't had any luck finding it. I suspect I need some sort of service manual or something to tell me where the darn thing lives. If anyone has any hints or tips, I'm all ears.
Thanks,
Erik