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Thread: Has anyone ever listened to their injectors?

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  1. #1
    Senior Member Josh S's Avatar
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    Has anyone ever listened to their injectors?

    While troubleshooting my engine yesterday I decided to listen to my injectors with a stethoscope and a couple sound like they are screeching... like an old 300 baud modem. I'm pretty certain that's not right. The majority of them sound like a nice oiled sewing-machine hum and click.

    Actually.. they all were fairly noisy at first, but most of them smoothed out while I was monkeying around. I did put a can of gas treatment in the tank earlier that evening. But perhaps that could be coincidence. However, the miss I was experiencing seemed to go away as well... and no noticeable stumbling on revving. I didn't have the time to take it for a road test last night, but I will today.

    Can anyone confirm what the injectors should be doing / sounding like? I don't imagine the sound of them should change much during operation. And I also assume they should all at the very least sound the same.


    Thanks!
    Josh
    "If you're going to spend your inheritance on a car, why not do it with some style!"

  2. #2
    Delorean Guru
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    A low screech. You may also be hearing air leaks past old, hard injector seals. The screech will get louder as the revs increase and they squirt more fuel. The frequency valve makes a buzzing sound that varies in frequency. The motor will hunt and you can hear the revs go up and down. A cacophony that you can hear as you walk up to a running PRV.
    David Teitelbaum

  3. #3
    Senior Member Bitsyncmaster's Avatar
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    When you do a flow test (put injectors in jars and press the air plate) you do get a screeching sound.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  4. #4
    Senior Member
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    Quote Originally Posted by David T View Post
    A low screech. You may also be hearing air leaks past old, hard injector seals. The screech will get louder as the revs increase and they squirt more fuel. The frequency valve makes a buzzing sound that varies in frequency. The motor will hunt and you can hear the revs go up and down. A cacophony that you can hear as you walk up to a running PRV.
    +10 points for excellent word choice.

  5. #5
    Member
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    Yes! I thought the same: just beautiful!!

    Quote Originally Posted by iflights View Post
    +10 points for excellent word choice.

  6. #6
    Senior Member Josh S's Avatar
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    Quote Originally Posted by iflights View Post
    +10 points for excellent word choice.
    Quote Originally Posted by dmcnc View Post
    Yes! I thought the same: just beautiful!!

    Totally thought the same. Just my post was getting too long.
    And you know, this morning it dawned on me.... instead of having 2 bad squealing injectors.... I have FOUR bad silent ones! That stinks.
    "If you're going to spend your inheritance on a car, why not do it with some style!"

  7. #7
    Guy with a DeLorean Mark D's Avatar
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    Quote Originally Posted by Lwanmtr View Post
    the squeal is caused by the hamsters inside the injectors being squeezed
    Quote Originally Posted by Josh S View Post
    Totally thought the same. Just my post was getting too long.
    And you know, this morning it dawned on me.... instead of having 2 bad squealing injectors.... I have FOUR bad silent ones! That stinks.
    So four deceased hamsters then?

  8. #8
    Senior Member Josh S's Avatar
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    Quote Originally Posted by Mark D View Post
    So four deceased hamsters then?
    Apparently so.

    The STP injector cleaner must have helped. Car ran great all weekend for DMA spring social.
    Got a few tips on cleaning them, and an offer of a tester/cleaner loan too.

    Thanks for the help everyone.
    "If you're going to spend your inheritance on a car, why not do it with some style!"

  9. #9
    Member
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    It's easy to jump the rpm relay and put the injectors in clear cups and watch their spray pattern. Look up the process.

    Sent from my SM-G920R4 using Tapatalk

  10. #10
    Member
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    Also I would say everything is ok. They do make a solid screeching sound. They flow constantly

    Sent from my SM-G920R4 using Tapatalk

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