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Thread: Tune out EGR Pattern Failure

  1. #1
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    Tune out EGR Pattern Failure

    I have a 2002 Firebird with the 3800. Occasionally I will get the "EGR stuck open" code P1404 after long distance cruising. It always goes away after a day or two. I have cleaned the EGR but no luck. I have read that a possible issue that is common on GM cars is EGR pattern failure, where the PCM does not give the EGR enough time to catch up, and therefore the PCM thinks something is wrong. In reality the EGR is fine, it's just not fast enough for the PCM's liking. The solution is to slow the PCM's check down just a bit. Any idea where this value is located? I will be getting HPT soon and this is one of several items I would like to fix. Thanks for any help.

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    Update - I have since purchased HP Tuners and to address this issue, I decided to try "desensitizing" the MIL by changing the DTC setting from 0 to 1. I still want the MIL to illuminate if a true problem exists. I think that the problem only happens intermittently, as stated above, when decelerating after a long cruise. I'm thinking that as long as the problem does not repeat itself in a reasonable amount of time, the computer will overlook the error. I guess that the only way I will ever know if the fix works, is that the MIL never again comes on when decelerating after an extended high-speed cruise.

  3. #3
    Advanced Tuner Dr. Nopps's Avatar
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    I can't even begin to tell you how much of a headache as well as time you can save yourself in the future by un-doing what you did, and dedicating your time and money twoards properly fixing that DTC issue. No check engine lights or codes is always the #1 rule before touching a car with your tuner. REMEMBER: Your car didn't leave the factory with that problem now did it? If you fixed everything to 100% OEM working condition, there should be no logical reason it would display any codes now that it wasn't displaying when it was new.
    Last edited by Dr. Nopps; 08-02-2012 at 01:59 AM.

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    Well, I'm not concerned about it. The EGR issue is a known problem because the GM electronic EGR valves sometimes don't react fast enough to satisfy the computer. It could be as little as one step of the stepper motor that the PCM sees as being an error. When this happens once and does not repeat, I don't want to be notified. However, with the new DTC setting, if it happens again, say, the next time I'm out driving, it will then set a code. Which is fine for me because then I am being notified of a real problem.

  5. #5
    Advanced Tuner Dr. Nopps's Avatar
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    You said you cleaned the EGR thinking it was giving you an issue. Try replacing it. Cleaning a broken one wouldn't do you any good. Not to crap on your skillz or anything. I'm just saying if you brought it to the best tech you could find- he would find out the exact cause of the problem and fix it. Not try to trick the PCM. Ocasionally they may have an OS update for certain cars so you can check with your dealership. They enter your VIN and any recalls or TSB's for your vehicle pop up. They can even see how many were already fixed at approved dealerships. Believe me, I know how much of a pain diag. can be! Hopefully you can use your scanner to find any major obvious signs of (small) trouble. The guy posting below me has a great idea. I'm gonna have to steal it and set that one up in one of my scanner config. files.
    Last edited by Dr. Nopps; 08-02-2012 at 06:53 PM.

  6. #6
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    I worked on a COMP G with a similar issue. I scanned desired EGR % and actual EGR %. I saw the computer commanding certain percentages but the actual wasn't moving. I pulled it off and soaked it in sea foam and WD-40. Put it back on, no more issues.
    2018 Camaro SS, Maggie 2650, 103 TB, Big Gulp, E85

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    Years-later update.... The EGR DTC P1404 being de-sensitized to activating the MIL after the second error has worked great for years. The EGR does actually work because the commanded and actual pintle positions are either right on or very close. Additionally, there are no driveability issues and the MIL has never illuminated for this code since I made the change.