Hello there and welcome to the BMW Car Club of America.

If you are a BMW CCA member, please log in and introduce yourself in our Member Introductions section.

Intake Whistle Sound

Discussion in 'E46 (1999-2006)' started by bmwsampc, Oct 23, 2008.

    bmwsampc guest

    Post Count: 8
    Likes Received:0
    Hey all, I have an 03 330i with the ZHP pkg. It's been a great car, but there is a slight whistle sound on the intake between 1500 and 2000 RPM. I did a quick check with the hoses and there doesn't appear to be a leak. Anyone hear of this or know of a service bulletin (dealership stated there wasn't one)?

    Jeron guest

    Post Count: 210
    Likes Received:2
    There are a lot of whistling sounds. The alternator makes a whistle, the cyclone separator whistles, a bad pulley bearing can make a noise like a whistle although it is more of a high pitch squeal than a whistle.

    I wouldn't want to tell you to ignore it but likely it is a "normal" engine sound.

    If you want to isolate it try a piece of PVC to direct your hearing and get a mechanics stethoscope to spot check parts.

    cmking guest

    Post Count: 16
    Likes Received:0

    Jeron guest

    Post Count: 210
    Likes Received:2
    A leak at the elbow should yield a CEL for lean mixture.

    Get in there and check the intake for leaks.

    samearle3 guest

    Post Count: 2
    Likes Received:0
    First off, I don't think a leak in the elbow would yield any kind of CEL because it is post MAF.

    Also, I had a whistle so I replaced the elbow. There was a crack in the elbow, but it didn't solve my whistle. And nobody else seemed to have a problem, but this was a pain to do! (my one tip would be to stretch the new elbow to get it to fit correctly on.)
    Good Luck
    • Member
    • Technical Service Advisor

    mooseheadm5

    Post Count: 1,880
    Likes Received:15
    Incorrect. Any air leak after the MAF can cause a CEL, but it does not care about air leaks in the airbox. Air that gets into the system past the MAF (as opposed to through it) is called unmetered air. The ECU injects enough fuel to mix with the metered air. If it looks at the exhaust gas and sees that the program is not injecting enough fuel (because air it does not know about is sneaking into the intake) then it can add more fuel to adapt, but only to a point. After that, on comes the CEL. In fact, about the only time people ever bring their E46s in lately is because the CEL is on, and when it is on for a mixture code (and possibly for poor running) we often find the intake boot(s) to be bad or the plastic connectors cracked. Sometimes we don't even have to open the hoods to "know" what is wrong (we check anyway, of course.) If we can't see it, we just smoke check the intake and find all the leaks. Sometimes the vapor separator is bad and causes the air leak/noise, and that shows up with a smoke test as well.
    • Member

    kevs330Ci

    Post Count: 22
    Likes Received:1
    it's the elbow.......mooseheadm5 knows what he's talking about....i have it come it in to my shop all the time......a must fix w/ the cost of gas.....

    samearle3 guest

    Post Count: 2
    Likes Received:0
    Let's be clear, I am not saying that what you have isn't a cracked intake boot, I am saying that you shouldn't rule it out just because you don't have CEL. My experience is that you can can have a large crack in your boot, but it might not trigger a CEL.

    Good Luck!

    Jeron guest

    Post Count: 210
    Likes Received:2
    The OP's question, was about a "slight whistle sound" with no mention of CEL or drivability problems. Like I said above, there several items that can make that noise during "normal" operation.

Share This Page