Injector Shutoff or FAS Switch

Discussion in 'General' started by diamondlarry, Jul 15, 2007.

  1. diamondlarry

    diamondlarry Super MPG Man/god :D

    There has been a lot of interest lately for a FAS switch or injector cut-off switch so I'll do my best to explain how I have done it on a couple of Saturn's. With that, I want to make sure that everyone understands that these are Saturn-specific so you will need to double check your vehicle before jumping in. I believe though, that most cars are wired in a similar manner so the directions should be pretty close for everyone else.

    You will need to get a 5-pin relay and a momentary contact switch, some electrical tape or shrink wrap, and some solder if you want. I haven't used the solder myself but if you fell safer with it then by all means do so.

    Ok. Lets get started. You will first want to locate the wires going to each fuel injector. On my car there were 2 wires to each injector. There was a wire of the same color going to each injector(pink) that supplies power and each injector also had another wire that was a different color than the one that was common to the other injectors. This is because the car's computer switches the ground to control the injector's pulse width.
    1) Locate the wires to the injectors that are the same color for all of the injectors and cut them.
    2) Strip the ends of the wires that are still connected to the injectiors and tie them together.
    3) Take the other end of the wires that are still connected to the wiring harness(these will be the wires that are hot when the ignition is on) and strip the ends and tie them together as well.
    4) Take the bundle of wires that are on the harness side and connect them to the input pin on the relay.
    5) Take the bundle of wires that are still connected to the injectors and connect them to the pin on the relay that is always on or "normally closed."
    6) Then, connect a wire from the relay's power supply circuit and run it to the bundle of wires that are hot when the key is on.
    7) Now, take a wire and connect it to the other relay power supply pin and route it inside the car's cabin.
    8) Connect the wire that you ran inside the car to one side of the switch.
    9) Connect a wire from the other side of the switch to a good ground.
    10) Before you button everything up, now would be a good time to test the switch. Start the car. If it doesn't start, it is most likely that you have connected the wires from the injectors to the wrong pin on the relay. Once the car is running, push the switch. The engine should die almost immediately.

    What is happening is this: When you push the button, the relay is energized and switches to the normally open contacts and the injectors lose power and quit injecting fuel. When the button is released, the relay is de-energized and reverts to the normally closed contacts so the injectors can function again. I like to use this method because the wire that is run inside is only enegized when the button is pushed and this seems to be safer.
     
  2. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Larry:

    ___I moved this to the Draft section uuntil you have included some pics and more details.

    ___Good Luck

    ___Wayne
     
  3. diamondlarry

    diamondlarry Super MPG Man/god :D

    Good, I was hoping you would. Thanks.

    Let me know what other details you would like to see and I will work on getting the pictures.
     
    Last edited: Jul 15, 2007
  4. diamondlarry

    diamondlarry Super MPG Man/god :D

     
  5. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    There has been a lot of interest lately in FAS or injector cut-off switches so I'll do my best to explain how I have done this modification to a couple of Saturns. Before beginning, I want to make sure everyone understands that these are Saturn-specific directions -- you will need to double check your vehicle before jumping in. I believe however that most cars are wired in a similar manner so the procedure should be pretty close regardless of vehicle make.

    In order to install this modification you will need a 5-pin relay, a momentary contact switch, some electrical tape or shrink wrap, and some solder if you want to make the connections more permanent. Though I didn't use solder in either of my installs, if you feel safer utilizing it then by all means do so where appropriate.

    [​IMG]

    Ok. Lets get started. First, you'll need to locate the wires going to each fuel injector. On my car there are 2 wires to each injector. One of these wires is the hot (power supplying) wire and for each injector this is the same color -- in this case that color is pink. The other wires are a different color -- they are the switched grounding wires used by the ECU to control injector pulse width.
    1. Locate the wires running to the injectors that are all the same color (the "hot" or power supplying wires) and cut them about midway along their length.
    2. Strip the ends of the wires still connected to the injectors and tie them together so that they make good electrical contact.
    3. Take the other ends of the cut wires still connected to the wiring harness (these will be the wires that are hot when the ignition is on), strip the ends and tie them together as well. Again, be sure that they make good electrical contact with each other.

      [​IMG]
    4. Take the bundle of cut wires still attached to the harness and connect them to the input pin on the relay.
    5. Take the bundle of wires still connected to the injectors and connect them to the pin on the relay that is always on or "normally closed."
    6. Now connect a wire from the relay's power supply circuit and run it to the bundle of wires that are hot when the key is on -- effectively creating a jumper between the two pins on the relay.

      [​IMG]
    7. Next, run a wire from the other relay power supply pin and route it inside the car's cabin.
    8. Connect the wire that you ran inside the car to one side of your switch.
    9. Connect a wire from the other side of the switch to a good grounding point. The red button below is my momentary contact switch:

      [​IMG]
    10. Before you button everything up, now is a good time to test the switch. Start the car. If it doesn't start, it is likely you have connected the wires from the injectors to the wrong pins on the relay. Check your connections and try again. Once the car is running, push the switch -- the engine should die almost immediately.
    11. My son also installed a toggle switch which will override the momentary contact switch. This can be used on long downhill stretches (such as mountains) so that the clutch and transmission can remain engaged. Because this will keep the engine spinning, the power brakes and power steering will continue to function. The 12V battery will also continue to be charged and the engine will act as a brake since this is effectively a manually induced DFCO condition.

      [​IMG]
    Here is how all of this works: When you push the button, the relay is energized and switches to the normally open contacts causing the injectors to lose power -- starving the engine of fuel and resulting in a stall. When the button is released, the relay is deactivated and an internal spring returns current to the normally closed contacts allowing the injectors to function once again.

    I chose this method because it ensures the wire that is run inside is only energized when the button is pushed. This seems safest to me. It will also allow the engine to function normally if the relay should fail -- the only thing that would be affected in this situation is the ability to kill the engine.
     
    Last edited: Dec 31, 2007
  6. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Larry, read over the above and let me know what you think? I added some clarifying verbiage -- please check to be sure I understood correctly what you were trying to communicate.
     
  7. diamondlarry

    diamondlarry Super MPG Man/god :D

    Sean, awesome job as I knew it would be!:) I have two suggestions:1)step #11
    2) I also need to give credit to the guy that showed me how to do this since it wasn't my original idea. His name is Mike Hollar and he is the owner/founder of www.mpgresearch.com.
    Thanks for the help!
    Larry
     
  8. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Larry:

    ___I need to shrink the pics down and format it for an article. Give me a few hours if you could. I have a ton on my plate today ;)

    ___Good Luck

    ___Wayne
     
  9. diamondlarry

    diamondlarry Super MPG Man/god :D

    Not a problem at all. I thought they seemed a bit on the large side myself. Also, if you think the pics need labeling for clarity, don't hesitate.
     
  10. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Ah, good. :) Glad to help, Larry.
     
  11. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Ah yes... I'll get these pictures shrunk down a bit this evening and add crediting to Mike Hollar at the bottom. I'll have to take a look at the reviews to see what we ought to do about formatting and then we can get it out there.

    Sorry again for the delay! This has been sitting here for a bit... :eek:
     
  12. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    There has been a lot of interest lately in FAS or injector cut-off switches so I'll do my best to explain how I have installed this modification in a couple of Saturns. Before continuing, I want to ensure everyone understands these are Saturn-specific directions -- I believe most cars are wired in a similar manner so the procedure should be adaptable to your particular make and model of vehicle .

    In order to build this modification you will need a 5-pin relay, a momentary contact switch, and electrical tape or shrink wrap. Neither of my installs used solder, but you can certainly do so where appropriate if you wish to make the connections more permanent.

    Ok -- let's get started. First, you'll need to locate the wires going to each fuel injector. On my car there are 2 wires to each injector. One of these 2 wires is the hot (power supplying) wire and it happens to be the same color for each injector -- in this case that color is pink. The other wires are a different color -- they are the switched grounding wires used by the ECU to modulate injector pulse width.

    Column1Column2
    [​IMG]
    • Locate the wires running to the injectors that are all the same color (the "hot" or power supplying wires) and cut them roughly half way between their attached ends.
    • Strip the free ends of the wires still connected to the injectors and tie them together so that they make good electrical contact.
    • Take the free ends of the cut wires still connected to the wiring harness (these will be the wires that are hot when the ignition is on), strip the ends and tie them together as well. Again, be sure that they make good electrical contact with each other.
    • Take the bundle of cut wires still attached to the harness and connect them to the input pin on the relay.
    • ---------


      Column1Column2
      [​IMG]
      • Take the bundle of wires still attached to the injectors and connect them to the pin on the relay that is always on or "normally closed."
      • Now connect a wire from the relay's power supply circuit to the bundle of wires that is hot when the key is on -- this effectively creates a jumper between the two pins on the relay.
      • ----


        Column1
        • Next, run a wire from the other relay power supply pin and route it inside the car's cabin.
        • Connect the wire that you ran inside the car to one side of your switch.
        • Connect a wire from the other side of the switch to a good grounding point. The red button in the picture to the right is my installed momentary contact switch.
        • Before you put everything back together, now is a good time to test the switch. Start the car. If it doesn't start, it's likely you've connected the wires from the injectors to the wrong pins on the relay. Check your connections and try again. Once the car is running, push the switch -- the engine should die almost immediately.


        • Column1Column2
          [​IMG]
          • My son also installed a toggle switch which overrides the momentary contact switch. This can be used on long downhill stretches (such as mountains) to allow the clutch and transmission to remain engaged while in a FAS. Because this keeps the engine spinning, the power brakes and power steering continue to function. The 12V battery also continues to be charged and the engine acts as a brake; essentially, this is a manually induced DFCO condition.
          • --------


            Here is how all of this works: When you push the button, the relay is energized and closes its normally open contacts causing all of the injectors to lose power. This starves the engine of fuel and results in a stall. When the button is released, the relay is deactivated and an internal spring returns current to its normally closed contacts allowing the injectors to function once again.

            I chose this method because it ensures the wire routed to the inside of my car is only energized when the button is pushed. This seems safest to me. It also allows the engine to function normally if the relay should fail -- the only thing affected in this situation is the ability to kill the engine.


            Special thanks go to Mike Hollar (owner/founder of http://www.mpgresearch.com) who showed me how to do this mod!
             
          • diamondlarry

            diamondlarry Super MPG Man/god :D

            Sean, it looks like another winner!:) I'll look for a good place to post it.
             
          • xcel

            xcel PZEV, there's nothing like it :) Staff Member

            Hi Larry:

            ___We have to place a top side format on it with a intro and a pic of your Saturn all by its lonesome and such. Why a FAS switch? What it does for your FE. Why would anyone want to go through this … I will be busy over the next 36 hours catching up and will help with that? Let us get it up by Friday if that is ok by you?

            ___Good Luck

            ___Wayne
             
          • xcel

            xcel PZEV, there's nothing like it :) Staff Member

            Hi Larry:

            ___We have to place a top side format on it with a intro and a pic of your Saturn all by its lonesome and such. Why a FAS switch? What it does for your FE. Why would anyone want to go through this … I will be busy over the next 36 hours catching up and will help with that? Let us get it up by Friday if that is ok by you?

            ___Sean, excellent use of the table command with a list vs. [xfloat]! When I was playing around with List and Tables using embedded [xfloat] tag’s, it was always a mess! Nice job!

            ___Good Luck

            ___Wayne
             
          • diamondlarry

            diamondlarry Super MPG Man/god :D

            Wayne, sounds good. I'll look and see if there are any suitable pictures of the Saturn in my photo gallery. If not, I'll take one when my son gets home from work tonight.

            As for one of the whys of a FAS switch, I got tired of losing mileage while waiting for the ICE to die. When I first did it on my original Saturn, I figure I gained 3-5% just by installing the switch alone due to the increase in mileage that was accounted for. If you think of any others, feel free to add them. I did post the article in the Hardware forum so you could probably just edit from there. Thanks.
             
          • diamondlarry

            diamondlarry Super MPG Man/god :D

          • xcel

            xcel PZEV, there's nothing like it :) Staff Member

            Hi Larry:

            ___You should delete it because it will have my edits all over it :( Wait until it is ready and post it into the Article forum or the HW forum and I can move it so it does not get buried so quickly!

            ___Remember this is going to the Article section so pics are of prime importance. Pull a brand new one in the sun with a good camera at max res and I can work with it from there.

            ___Good Luck

            ___Wayne
             
          • diamondlarry

            diamondlarry Super MPG Man/god :D

            I'll keep an eye out here for your final editing. I'll be off on Friday(and probably up way to late Thursday night:D) so let me know if you need any more details/information.
             
          • Right Lane Cruiser

            Right Lane Cruiser Penguin of Notagascar

            Thanks, Wayne. :) When playing with it I was near pulling out my hair until I settled on what you see now. Even then it didn't look right and I had to add some whitespace to get the text to center properly...

            It still doesn't look quite the way I wanted but at least it is close.

            I'm looking forward to seeing this in the articles section! :thumbs_up:
             

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