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Thread: Still having idle issues--injectors??

  1. #1
    Join Date
    Jul 2016
    Location
    Austin Texas
    Posts
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    Still having idle issues--injectors??

    Hope everyone is having a nice November

    My ZHP is still idling a little on the rough side. It's not a cold idle, it's usually after it warms up. Car starts fine, cold idle is fairly smooth, but once the revs drop to about 700 or so when it's warmer, it begins to stumble a little. I can feel it in the car and see it on the tach. Driving is fine, no noticeable loss of power or anything like that, but when I come to a stop, revs sometimes drop to about 500 and it again stumbles somewhat.

    There are no codes.

    Here is everything I've replaced:

    CCV
    Intake manifold gasket
    Valve cover gaskets
    Air filter
    Fuel filter
    Spark plugs
    Brake booster vacuum valve
    Camshaft sensor (intake)
    Alternator
    Battery

    Rebuilt:
    DISA (G.A.S. kit)
    VANOS (seals)

    Cleaned:
    Idle control valve (cleaned it like 5 times by now!)
    MAF sensor
    Throttle body

    Smoke test has been performed and leaks were fixed.

    I'm wondering if I should replace my injectors. I tried getting readings using INPA but was having difficulty (all just module timeouts). In different software, I'm getting different values for "Average rough idle" across cylinders. Most read values of "15.xx" and others are "0". I'm not exactly sure what this is measuring though.

    Any ideas/feedback would be appreciated, as always
    Last edited by usinjin; 11-18-2020 at 12:14 AM. Reason: Yes, ICV has been cleaned
    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

  2. #2
    I just did my intake manifold removal cooling system replacement and everything that goes with it, including the oil sep system and cleaning the ICV valve.

    I cleaned the throttle body and reset the adaptations. I’m also getting weird idling. My suspicion is the dual-mass flywheel. It doesn’t bother me tremendously, and usually a rev will clear things up.

    [edit]

    Actually you probably need to reset your adaptations (you never mentioned this), and then it’ll take a few days for it to smooth out.
    Last edited by Fried_Chicken; 11-19-2020 at 09:07 AM.

  3. #3
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    Jul 2016
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    Quote Originally Posted by Fried_Chicken View Post
    I just did my intake manifold removal cooling system replacement and everything that goes with it, including the oil sep system and cleaning the ICV valve.

    I cleaned the throttle body and reset the adaptations. I’m also getting weird idling. My suspicion is the dual-mass flywheel. It doesn’t bother me tremendously, and usually a rev will clear things up.

    [edit]

    Actually you probably need to reset your adaptations (you never mentioned this), and then it’ll take a few days for it to smooth out.
    My bad, you're right, totally forgot to mention, did reset all the adaptations (whoops, bucked like mad until I did the throttle reset!), and I've actually driven it about 500 miles--still a little rough. Before resetting the fuel trims were close to -10%, likely because of the leaks I'd fixed, but now it is back around 5%.

    The thing is, it used to idle smoother, so I feel like it definitely /can/ idle smoother, but I'm running out of things to replace!
    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. #4
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  5. #5
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    Quote Originally Posted by Will View Post
    My random guess: Oil filler cap?
    I've done that before...

  6. #6
    Quote Originally Posted by usinjin View Post
    My bad, you're right, totally forgot to mention, did reset all the adaptations (whoops, bucked like mad until I did the throttle reset!), and I've actually driven it about 500 miles--still a little rough. Before resetting the fuel trims were close to -10%, likely because of the leaks I'd fixed, but now it is back around 5%.

    The thing is, it used to idle smoother, so I feel like it definitely /can/ idle smoother, but I'm running out of things to replace!
    Hhhmmm... my money is on something simple/stupid. I'd run another smoke test. Otherwise it could be the flywheel (mine rattles on occasion while idling).

  7. #7
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    Quote Originally Posted by Will View Post
    My random guess: Oil filler cap?
    Been replaced as well, OEM cap and new gasket too.

    Quote Originally Posted by Fried_Chicken View Post
    Hhhmmm... my money is on something simple/stupid. I'd run another smoke test. Otherwise it could be the flywheel (mine rattles on occasion while idling).
    Another smoke test it is. Did the rubber glove-over-the-upper-boot method and after filling it with smoke, it stayed inflated for several hours before I ended up removing it. Not sure what else I could replace. Every single rubber thing/hose that even looked warn has been replaced.

    I feel like the flywheel is a bit more far-fetched...how could it be causing the revs to bounce up and down?
    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

  8. #8
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    Another random guess: the vacuum lines from the intake boot "F" connector down to the fuel pressure regulator (One at the F connector and one rubber vacuum line down by the fuel filter).

  9. #9
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    Quote Originally Posted by Will View Post
    Another random guess: the vacuum lines from the intake boot "F" connector down to the fuel pressure regulator (One at the F connector and one rubber vacuum line down by the fuel filter).
    The f connector and the fuel vacuum line have been replaced too :|
    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. #10
    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.

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