Egr delete.. chip?

Discussion in 'Engine Performance + Maintenance' started by Keven, Dec 26, 2016.

  1. Keven

    Keven OBS Enthusiast

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    I got a truck that had egr delete.. but i heard its not really good for an engine if it havent been tune? How can i tell if it was?
     
  2. Keven

    Keven OBS Enthusiast

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    Coz almost all the egr system components are tgere so i could just hook it back if its not properly tuned.. is it in the ecm? The truck is actually sitting in the garage and cant drive for a lil while just trying to figure out if there is an easy way to find out without checking mpg or stuff like this..
     
    Last edited: Dec 26, 2016
  3. MarkZ28

    MarkZ28 Newbie

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    Running the engine without egr will only make it run better, or at worst, no change. I removed the egr on my 89 long ago and has no effect. Same with all my other vehicles it was removed from. Your check engine light will come on.
     
  4. df2x4

    df2x4 Domestics only.

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    Even if you don't notice it running any worse with the EGR deleted and no tune, it certainly is. Hook up a scanner and monitor live data, you'll see.

    If it's not deleted from your tune, I don't recommend deleting it physically.

    To answer the question about how to see if it's deleted from the tune... Pull the codes. If the check engine light isn't on and it doesn't throw any EGR codes, then it's probably been tuned out.
     
  5. GMRedline

    GMRedline I'm Awesome

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    What does it mean to "tune out" the EGR? Is disabling the code all people do? Or do they make changes to the PCM calibration?
     
  6. df2x4

    df2x4 Domestics only.

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    Changes are made so that the engine never even tries to open the solenoid. It's more involved than just disabling the CEL.
     
  7. Supercharged111

    Supercharged111 I'm Awesome

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    When the PCM commands the EGR to open, it also leans out the fuel mixture and advances the timing. If the EGR isn't allowing exhaust flow into the intake, it will cause detonation. On the other hand, my truck threw a CEL for inadequate EGR flow, so I'm not sure if the computer is smart enough to know the EGR isn't working and doesn't make those changes or what.
     
  8. GMRedline

    GMRedline I'm Awesome

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    Well I finally looked hard enough and found some stuff using HP Tuners. This is EGR stuff in the 98-99 Vortec PCM Black Blox.

    First there is the Min VSS on the Engine General tap.
    [​IMG]

    The table goes from 0 to 256mph. It would appear that setting this above the vehicles top speed or 256 would never allow the ERG to function. Since it says "Below this vehicle speed, EGR is disabled."

    Then there is a Diag. Enable Speed.
    [​IMG]

    Setting this parameter at 256 would disable the EGR diagnostics which should stop any CELs? Maybe.

    This is the EGR Spark (Timing) Modifier table.
    [​IMG]

    That could always be zero'd out so the PCM would never add any timing based on EGR function.

    I couldn't anything EGR related in regards to fueling.

    On the newer GM PCMs (411) it looks like they have a simple Enabled/Disabled toggle.

    [​IMG]

    The newer PCMs also have a simular Spark modifier table but I couldn't find anything in the fueling.
     
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  9. GMRedline

    GMRedline I'm Awesome

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    From what I found, I would have to agree with this. I wouldn't consider myself an expert tuning a Vortec 350 yet but I'm learning.

    It's certainly possible that the engine would run worse without an EGR that hasn't been properly tuned for. With a properly functioning EGR, the PCM adds timing to the Main Spark table. Without the additional recirculating exhaust the additional timing might be too much causing pre detonation or engine knock.

    Even with the EGR properly removed from the tune, the engine will still not run as much timing causing lower fuel economy. The more timing the more power the engine makes. The more power the engine makes the better the fuel economy under cruise.

    From the other point of view, disabling the EGR properly could make up the difference in loss of timing because of the cooler/denser air. With a custom tune, more timing could be added to the Main Spark table because of the cooler/denser air. So maybe more peak hp could be made from a performance standpoint but the fuel economy will suffer.

    All this may seem obvious but I'm just thinking out loud right now. I've always wanted to delete my EGR because I can't wrap my head around adding hot air back into the engine. And I don't like what the EGR does to the intake manifold.
     
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  10. Chewy1576

    Chewy1576 I'm Awesome

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    When I started doing the tuning for my 383, the first change I made was disabling the EGR. I zeroed all of the fuel and spark tables, as well as disabling the EGR related codes. Physically, all EGR components are still on the engine for emissions purposes, but they don't do anything. I even put a thin aluminum plate between the EGR valve and intake to act as a block off plate. In a few years when I can register the truck as a "vintage" vehicle and gain emissions exempt status, it will all be going bye-bye.
     

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