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Thread: 2009 hhr Suspect ecm going out

  1. #1
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    2009 hhr Suspect ecm going out

    I have a 2009 Chevy hhr 2.0 turbo. Cold the idle surges bad, Once into closed loop the idle jumps up to 1,400-1,500 rpms and wont come down. Fuel trims will be great one time, then the next time you start it, there at -30% with no changes to the ecm.... Did install a new mass air flow sensor. Still same results. suspect the ecm is going out,,,, But maybe i have missed something in the tune... Please let me know your thoughts? Or changes i should try?
    I'll upload my tune and data log2009 chevy hhr mod tune36.hpthhr closed to open loop1.hpl

  2. #2
    Senior Tuner cobaltssoverbooster's Avatar
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    if you put your bone stock file in does it run like its supposed to?
    2000 Ford Mustang - Top Sportsman

  3. #3
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    this Problem didnt start from a tune change. It devolved over time. I have tried previous tune that i know run great with no change.That is why i'm suspecting a ecm going out,,, I have smoke tested for vacuum leaks, Non found.

  4. #4
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    Quote Originally Posted by TOY8490 View Post
    this Problem didnt start from a tune change. It devolved over time. I have tried previous tune that i know run great with no change.That is why i'm suspecting a ecm going out,,, I have smoke tested for vacuum leaks, Non found.
    Any dtc's that point to the ecm going out?

    The odds of the ecm taking a dump vs some other issue are very slim ie less than 1% IMO especially on a car thats 10 years old or less.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  5. #5
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    i'm getting a p0507 idle higher than normal,,, That is my only code, currently,,,,,, Sometimes it does get the Rich at idle code when the fuel trims go rich on there own...... then the next time i start it the fuel trims are perfectly normal...... The car does have 340,000 miles on it.

    I'll see if i can capture the good fuel trim log,,,,,, and all of this is with no tune change.

  6. #6
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    data log #2

    hhr closed to open loop2.hpl

    Did another data log, left car idling,,,,, Seen short term trims were normal,,, took a short test drive,,,,, Came back and fuel trims are at -30% short term...... Idle stays around 1,200-1,300.

    something very odd,,,, Turn the key off, Engine shuts off, once your hear the motor stop turning,,,, Then there is a back fire sound like out of exhaust...... I think i'll try and get a video of that.
    Last edited by TOY8490; 09-12-2019 at 07:10 PM.

  7. #7
    Senior Tuner cobaltssoverbooster's Avatar
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    unplug your evap hose and install a vacuum cap. sometimes they fail and pull air through the system. quick and easy check for extra air concern due to high idle codes.

    have you performed a cylinder leakdown test to verify you dont have any undesired cylinder leaks?
    injector seals like to go bad too. typically their compressed installation does not show a smoke leak because 1) the cylinder pressure is deflecting the seal 2) the rail is wrapped in high density foam and can mask a small leak. when was the last time they got replaced?


    since multiple tune files including the original are running the same, it is more likely the ecu is fine and their is a mechanical issue. When testing, the ecu is innocent until proven guilty, which means until all avenues of mechanical concern have been ruled out.
    Last edited by cobaltssoverbooster; 09-13-2019 at 12:34 AM.
    2000 Ford Mustang - Top Sportsman

  8. #8
    Also suspect cam timing the top guide bolt is prone to breakage as well as phaser failures at those kind of miles