Disable the EGR system the (mostly) Toyota way

Discussion in '80-Series Tech' started by Ebag333, Aug 31, 2009.

  1. Ebag333

    Ebag333

    Messages:
    8,163
    Location:
    Medford, OR
    So I recently disabled my EGR system, and was looking into disabling the temp sensor. I was all set to use the resistor trick, when tblume posted his thread that got me thinking.

    Evidentially, for ODB-1 and ODB-2 trucks there is a very easy way to disable the EGR system. Create an continuous loop on the EGR temp sensor circuit (bypassing the temp sensor). No resistor needed. Here's how I did it on mine.



    Using the part number from tblume's truck (82824-35020), I ordered two (one for my truck, one for the :princess:). Here's his pic, when I get my truck back I'll try and remember to post a better one.

    [​IMG]


    Upon receiving them, I found that they plugged into the sensor side of the plug. Here's a pic of tblume's wiring for reference (Note: This is an OBDI truck, so the temp sensor is on the other side from the OBDII trucks, you can see the bolt capping off where his sensor would go):
    [​IMG]

    Here's a picture of mine. Apologies for the poor pic, it was getting dark and my camera suddenly decided it didn't want to take pictures with it that dark.

    [​IMG]

    [​IMG]

    Yes, the bolt isn't all the way in. It was too long and I had to trim it, which I did after taking that picture.

    You can see I'm holding the wiring for both the sensor side and the ECU side. I simply took my dremel and trimmed down the box section to match the sensor side. When you look at the terminals, it'll make a lot more sense.

    Once I trimmed it, it slid in easily but never gave that satisfying *click* that the originals did. So I did what any self-respecting shade tree mechanic would do. I put a dab of super glue on the boots to hold them in place. :hillbilly:

    Honestly, I have no fear of them coming out even without the super glue, but I tend to be overly cautious.


    Here's a picture of it (nearly) completed.
    [​IMG]

    I simply snapped the cap on, then zip tied it up against the brake booster to keep it out of the way. Once I was done, I could hardly tell that it wasn't OEM. :grinpimp:



    To make this work you have two options. Basically you want to swap the ends that are used, so that you can plug in your cap into the correct side.
    • You can use a terminal pick to remove the wires from the plugs, and then modify the ends of terminals to match. This sounds confusing, pics are worth a thousand words. I simply snapped off the excess length with a pair of pliers, then used a dremel to trim the "box" part down to match. Once you have the terminals side by side it'll make sense.
    • Cut and reattach the two sides. This has the advantage of being able to unsnap your cap, and snap your temp sensor back into place, re-enabling the EGR temp sensor probe in a matter of seconds. Using solder and a bit of heat shrink, and you should be able to make this invisible to any nosy emissions inspectors.


    The redneck guide:

    1. Unplug the temp sensor.
    2. Take a paperclip.
    3. Stick one end of the paper clip into the plug (ECU side, not sensor side).
    4. Stick the other end of the paper clip into the plug. (Other open hole.)
    5. Duct tape in place.
    6. Step #6.


    The only other challenges you'll face is disabling the EGR modulator, and blocking off the EGR temp sensor probe hole, should you choose to remove it.

    I'm not sure if disabling the EGR system in this manner will also automagically disable the EGR modulator. I used JB Weld to block off the EGR modulator on my truck, I will try this method with a working EGR modulator on the :princess: truck and see if it fully disables it.

    For the EGR temp senor probe hole, I just sourced a bolt to match from my local Ace. (Note to self, find the size/pitch.)

    That's pretty much it. If you don't care about using an OEM part, just throw in a bit of wire to create a loop, and forget about the resistor.



    Here's why to disable the EGR system:

    Last edited: Sep 11, 2009
  2. alia176

    alia176 SILVER Star

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    Sorry, I'm not picturing what you're trying to describe with the plug and terminals! So I'll wait till you take some pics! It sure does sound cool though and I'll copy it.
  3. Ebag333

    Ebag333

    Messages:
    8,163
    Location:
    Medford, OR
    Basically if you take the terminals out of the connectors, and hold them side by side, you will see what I'm talking about.

    Pics will come when I get my truck back from getting the new exhaust. :)
  4. IdahoDoug

    IdahoDoug

    Messages:
    8,783
    So, assuming the EGR code causes the engine to react somehow (I think I've read some people getting poor MPG due to the 401 code??), will your fix cause the engine to operate in normal mode? I'm hoping so, as I'll be doing this within the week if so. Pics please.

    DougM
  5. gotmud

    gotmud

    Messages:
    2,117
    Location:
    Gilbert, AZ
    ***Slight hijack / update***

    Ebag333's tip is trick since it allows you to bypass the temp sensor. Personally, I'm sold on removing the egr completely, though this might not be feasable if you live where smog testing is done. If you can remove it due to the lack of e-check requirements, it will make things cooler. As I stated before, my wiring harness was not only heat damaged, but also appeared frayed from rubbing against the egr pipe. Blocking off the egr and removing the associated plumbing (including the installation of a pipe plug in the head) has paid off considerably for me. The wiring is safely away from both a heat source and physical contact. My intial highway MPG (keep in mind this is a new motor) was around 17.5 and has increased slightly to 18.1. This could be for a variety of factors, not just the EGR. Nonetheless, it appears removing/disconnecting the EGR does not have any detrimental effects on the driveability as others have cautioned about. YMMV
  6. Ebag333

    Ebag333

    Messages:
    8,163
    Location:
    Medford, OR
    I don't really see how people are getting more than 1-2 MPG difference with EGR dis/enabled. Personally, I saw zero difference in the MPG after I disabled mine, and my EGR system passed all the FSM tests that I threw at it when I tested it a while back.

    It's possible that with the EGR throwing a code (insufficient flow) that the ECU will change the flow of fuel slightly in an attempt to compensate, but I don't see why it would.


    Operate in normal mode? The "normal" mode is for EGR to be enabled and active. This allows you to disable the EGR system in a very OEM/stealth fashion.


    Yeah yeah. :rolleyes:


    Not a hijack at all. And a great post. :cheers:

    I don't have the issue of my wiring harness (as far as I can tell) rubbing the EGR pipe, but I can very much see the issue of the pipe toasting the harness. Mine isn't brittle or anything yet, but it's definitely headed in that direction, and my hope is that by disabling it the remaining heat won't be enough to damage the heat shielding around the harness any further.

    Aside from saving the harness, some other potential benefits are:

    Less junk going back into your engine (since you are no longer recycling exhaust, it should burn much cleaner and stay much cleaner).

    Possibly stave off HG damage. There's no hard scientific evidence or proof, but there's a lot of anecdotal evidence. For one, the design of the intake/EGR mean that the majority of the recycled gas goes into cylinder 6. Around cylinder 6 is where the HG usually pops. Non-EGR equipped trucks seem to have less of an issue with HG's popping than EGR equipped trucks. Coincidental? Possibly....but I don't think so.
  7. tblume

    tblume

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    1,077
    Location:
    willamette/umpqua divide

    enough for me.. now to look up deleting the PAIR device, somebody popped up that they had done it, can't remember when or where, even why; but I am curious by nature.:D
  8. gotmud

    gotmud

    Messages:
    2,117
    Location:
    Gilbert, AZ
    I deleted my PAIR shortly after owning my '94. IIRC, it was pretty straight forward. -A couple of vaccum lines, removing the valve, and blocking the fresh air hose at the air cleaner housing. For the exhaust manifolds, I tapped the center hole and inserted a pipe plug. I'm sure I missed some other details, but this should get you on your way.
  9. alia176

    alia176 SILVER Star

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    tapping my fingers on the table. Is the truck back yet? :D
  10. UCBerzerkeley

    UCBerzerkeley

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    SF Bay Area
    Ok, I am a fool when it comes to this type of stuff. Is everyone excited because the EGR is frankly annoying, and can now get rid of it in an OEM way?
  11. Ebag333

    Ebag333

    Messages:
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    Location:
    Medford, OR
    The exhaust is finished! :bounce:

    Only problem is....it's still 5 hours away and I can't get it until Thurs (at the earliest). :doh:

    Basically, yes.

    The other way was to add a resistor. This way you don't need to worry about all that, just create an open loop and you're done.

  12. tblume

    tblume

    Messages:
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    Location:
    willamette/umpqua divide
    and the result was?? all I know is on my '93 it makes a bunch of unnecessary noise before it warms up and after I forget it's there...

    I guess I can read up on it in the FSM, search has yielded little.

    sorry to HiJack Gabe, waiting patiently for your pics of the exhaust though :D
  13. gotmud

    gotmud

    Messages:
    2,117
    Location:
    Gilbert, AZ
    Honestly, I don't think it made much difference at all. Other than what you mentioned regarding noise. I do have more room under the hood and a little less plumbing. I installed a bypass pipe from a 95+ in case I ever decide to do an OBA system.

    [​IMG]
  14. alaskacruiser

    alaskacruiser

    Messages:
    1,540
    Location:
    LA, CA
    Ebag- Will a truck with this mod still pass CA emissions? I don't know enough about emissions equipment to know the answer to this question... Also, please let us know if the JBWeld did the trick in disabling the EGR modulator. I'm wondering if there's any way to keep all the EGR equipment installed while also installing a blockoff plate? Awaiting pics, Ebag!
  15. Ebag333

    Ebag333

    Messages:
    8,163
    Location:
    Medford, OR
    The EGR should only operate at cruising speed and only at partial throttle. I have a hard time imagining how it kick in for a test.

    Regardless, I don't think it'll make much difference one way or another. (Else I wouldn't be disabling mine.) The 1FZ was designed to run without the EGR, and seems to run just happily with it disabled.

    That being said........

    /inset standard warnings about disabling emissions systems, etc.


    Don't need a blockoff plate. The JB weld will do the trick. My next test is to see if creating an open loop causes the ECU to never open the EGR modulator, meaning all you'd have to do is snap in the cap that I referenced, and it'd be fully disabled. I'll check that on the :princess: truck next.

    That'd be trick, because if you swapped the connectors for the temp sensor you could unplug the cap and plug back in the temp sensor, re-enabling the EGR system in a matter of minutes (or even seconds).

    That's all theory though.
  16. alia176

    alia176 SILVER Star

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    alright, alright, your 80 is now back in the garage. Now, let's see some pics damn it :)
  17. Slowleak

    Slowleak

    Messages:
    119
    Location:
    Hickory, NC
    Sorry, I may have missed something here all along, but is this mod for getting better MPG?
  18. Ebag333

    Ebag333

    Messages:
    8,163
    Location:
    Medford, OR
    No.

    In theory the EGR is supposed to give you slightly better gas mileage. In reality folks have switched between disabled and enabled EGR (intentionally or unintentionally) or vice versa, and haven't seen it make a lick of difference. I know personally I have not seen a difference.

    Here's why to disable it:

  19. landtank

    landtank SILVER Star

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    Groveland MA
    what's the point of this? I had the P0401 on my truck, found the problem and fixed it.

    Is there some kind of reward for doing this or is it just to do it because.
  20. Ebag333

    Ebag333

    Messages:
    8,163
    Location:
    Medford, OR
    Is this a serious question? Did you not read the post right before yours?

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