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Thread: Still having idle issues--injectors??

  1. #11
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    How many miles on your O2 sensors? They soft-fail around 100k miles.

  2. #12
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    Use OBD Fusion and an OBDII WiFi adaptor to view your short term fuel trims, MAF data and O2 sensor voltages. I had poor idle and that's how I tracked it down.

  3. #13
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    Quote Originally Posted by Fried_Chicken View Post
    Truly a mystery, time to dig down.

    What's the mileage of the car? Have you hooked up a computer to read codes that might be present but not throwing a CEL? At this point a proper diagnostics is in order - guessing and replacing parts will not do.

    You mentioned spark plugs, but not coils. Coils tend to fail after ~100k miles, although if you didn't replace them, they shouldn't introduce a rough idle. You said you replaced the CCV, did you also replace all the hoses associated with it? These can get clogged along with the CCV, although if it didn't manifest before, it shouldn't manifest now.

    As I'm writing this, I think the most suspicious item is the MAF. I don't like touching MAF sensors, they are super finnicky. If you did clean them, did you use the right type of spray? It's critically important you do. The wrong type of spray will leave oil residues, and permanently damage it. If you can quickly swap out another MAF, you can get your answer quickly. Alternatively, try spraying with the appropriate spray. You might have to again reset adaptations, although I don't think so.
    Car has 150,xxx miles. No codes whatsoever from ECU (except SAP, which has been coded out anyways).

    Do coils soft fail at all? Not misfiring, so they didn't seem likely to me.

    CCV was replaced, OEM unit and all hoses as well. When I pulled the intake off I inspected all the hoses again and they were good.

    MAF was cleaned a couple of time with CRC mass airflow sensor cleaner. After spraying, it was left in a clean environment outside of the car overnight to dry. I've never touched any part of it besides the outer plastic housing. Don't have another MAF to test unfortunately.
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  4. #14
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    Quote Originally Posted by Dave1027 View Post
    Use OBD Fusion and an OBDII WiFi adaptor to view your short term fuel trims, MAF data and O2 sensor voltages. I had poor idle and that's how I tracked it down.
    Prior to an exhaust leak, I was seeing 7-12% on average for the fuel trims. After fixing, about -15%. After resetting adaptations and driving 500+ miles, they're at about 6%.

    I hadn't realized I could actually diagnose using voltages. What is the range they should be in?
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  5. #15
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    BTW, as a side note: what did you find in regards to the wonky ride heights (link)?

  6. #16
    Quote Originally Posted by usinjin View Post
    Car has 150,xxx miles. No codes whatsoever from ECU (except SAP, which has been coded out anyways).

    Do coils soft fail at all? Not misfiring, so they didn't seem likely to me.

    CCV was replaced, OEM unit and all hoses as well. When I pulled the intake off I inspected all the hoses again and they were good.

    MAF was cleaned a couple of time with CRC mass airflow sensor cleaner. After spraying, it was left in a clean environment outside of the car overnight to dry. I've never touched any part of it besides the outer plastic housing. Don't have another MAF to test unfortunately.
    Did the rough idle start suddenly? Do you know when it started relative to any parts you replaced? If you do, that's the first place I would look.


    I think it's a safe assumption that the intake is fine at this point. You say you reset the adaptations, have you had the car in an idle situation long enough? It might still be learning the adaptations (I assume it needs the engine under all conditions, so simply driving 500 miles wouldn't give it that). I had a rough-ish idle after doing the manifold out procedures (coolant lines, etc), cleaning the throttle body, and resetting the adaptations. It took a bit for my idle to normalize.

  7. #17
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    Quote Originally Posted by usinjin View Post
    Prior to an exhaust leak, I was seeing 7-12% on average for the fuel trims. After fixing, about -15%. After resetting adaptations and driving 500+ miles, they're at about 6%.

    I hadn't realized I could actually diagnose using voltages. What is the range they should be in?
    The Pre-Cat O2 sensor voltages should be in the 1 volt range. They don't deviate much.

  8. #18
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    Quote Originally Posted by Will View Post
    BTW, as a side note: what did you find in regards to the wonky ride heights (link)?
    Thanks for asking--you know, I'm convinced it was something like 20% my imagination, even though I did measure and there was a considerable difference in wheel well clearance on either side--I removed both shocks, replaced both rear shock mounts, wrestled springs around on both sides to make sure they were in the same place, everything else looked symmetrical. It still was a little wonky, and I gave it up for the time being.

    Checked again recently, and the back was even again. I guess it needed time to settle?
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  9. #19
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    Quote Originally Posted by Dave1027 View Post
    The Pre-Cat O2 sensor voltages should be in the 1 volt range. They don't deviate much.
    Post-cat O2's are not present in the car (catless headers), they've also been coded out. Pre-cat voltages are fluxuating between 1.46v and 1.55v approximately.
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  10. #20
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    Quote Originally Posted by usinjin View Post
    Thanks for asking--you know, I'm convinced it was something like 20% my imagination, even though I did measure and there was a considerable difference in wheel well clearance on either side--I removed both shocks, replaced both rear shock mounts, wrestled springs around on both sides to make sure they were in the same place, everything else looked symmetrical. It still was a little wonky, and I gave it up for the time being.

    Checked again recently, and the back was even again. I guess it needed time to settle?
    Nice, glad it's even. Might have been the uneven / sloping ground, I thought my m3 was off by 1/2"-3/4" in a corner but when I measured on flatter / less sloping ground it was about even (1/4").

    Quote Originally Posted by usinjin View Post
    Post-cat O2's are not present in the car (catless headers), they've also been coded out. Pre-cat voltages are fluxuating between 1.46v and 1.55v approximately.
    Quote Originally Posted by Will View Post
    How many miles on your O2 sensors? They soft-fail around 100k miles.
    How old are those o2 sensors?

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