09-29-2021, 08:37 PM | #1 |
Drives: 2010 Camaro SS L99 Join Date: May 2019
Location: New Orleans
Posts: 119
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Misfires, spark knock and hissing sound. Related?
Hey car geniuses I got another for you..My L99 has been lacking power at low rpms when in both closed loop and open loop. It feels and sounds slightly off. I also heard a slight tapping sound that sounds to me like spark knock around the bank 2 exhaust manifold area. I'm getting about a degree or 2 of knock retard, only for a couple of seconds at a time, usually when I give it some gas. The knock also happens while I'm cruising, but it's less frequent. I also hear a pretty loud hissing sound coming from the driver side of the exhaust manifold, but I'm not sure if this hissing is normal or not. Could it be just a hissing from the evap or fuel rails or is it likely from a vacuum leak? Not getting any codes, already replaced all spark plugs and checked my exhaust for leaks/clogs. The only other strange thing is my evap test is not passing, but it's not setting a code either. The evap test conditions have been met 7 times but the test hasn't passed yet.
Is the hissing normal for the L99 on the driver side? Any other ideas? Thanks. |
09-29-2021, 08:38 PM | #2 |
Drives: 2010 Camaro SS L99 Join Date: May 2019
Location: New Orleans
Posts: 119
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Only mods are z28 air intake and high flow cats. No tune. This problem just started out of nowhere.
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09-29-2021, 09:28 PM | #3 |
Drives: 2015 zl1 m6 Join Date: Jan 2020
Location: Alaska
Posts: 702
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Can you post a vid ? Does the tapping noise get louder when accelerating?
Knock sensor listen for knock so they can pull timing . As far as the hissing sound could be a vacuum leak to exhaust leak a lot of different types of hissing noises |
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