Engine noise while accelerating on gas 15-30mph?

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by Mrd9940, Oct 2, 2025 at 5:44 PM.

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  1. Mrd9940

    Mrd9940 New Member

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    I have a 2020 prius prime plug in with 52,000 miles. When driving on gas up hill between 15-30 mph there is a rattrling engine noise that appears intermittently. Takes a while to hear the nouse but only happens going up hill on gas. Toyota mechanic could not detect the problem. Does not occur on speeds above 35mph.
     
    #1 Mrd9940, Oct 2, 2025 at 5:44 PM
  2. bisco

    bisco cookie crumbler

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    is the car new to you, or did the noise start recently?

    maybe some sheet metal vibrating against the exhaust manifold/cat/tailpipe?
     
    #2 bisco, Oct 3, 2025 at 3:30 PM
  3. BiomedO1

    BiomedO1 Senior Member

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    More than likely, your engine is pinging from low octane gas. Try filling your tank with higher octane gas next time to see if your problems persist. It may also just be old gas; if you fill-up less than once a month. Stale gasoline. Someone here just paid a dishonest dealership $3K for that diagnosis after a bunch of parts swap-outs. Dealership claimed the bad gas damaged those parts.o_O:rolleyes::whistle:

    Hope this helps....

    PS, don't use octane boost - that can mess-up your CAT if it's the wrong formulation.
     
    #3 BiomedO1, Oct 3, 2025 at 6:00 PM
    Last edited: Oct 3, 2025 at 11:21 PM
  4. Mrd9940

    Mrd9940 New Member

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    Thank you tried that and had the all those metal parts tightened or added screws. Sound has been going on very intermittently since 20,000 miles or so.
     
    #4 Mrd9940, Oct 5, 2025 at 5:35 PM
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