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[quote=Anonymous][quote=Anonymous]We have 2010 Honda Odyssey V6 engine with around 60,000 miles, during acceleration, especially with the engine speed is less than 2500 RPM, you can hear rings clanging sound. We've replaced the spark plugs which did not help, but then moved from using 87 octane to 93 octane fuel, plus using a fuel cleaner every 3-6 months, that seemed to have helped (75%) but not entirely. Any idea what is causing this, perhaps its the (lose) piston rings or engine pre-detonating a milliseconds to early, and if so, what can be done to remedy it, if at all?[/quote]

A couple thoughts:  it might not be knocking/pinging/predetonation. It could be lifter or valve noise from a stuck lifter or low oil pressure. But the fact that it cleared up partially with increased octane also might mean you’ve got two different things going on, knocking AND lifter chatter. The higher octane cleared the knocking, allowing you to hear the lifter chatter isolated by itself now.

Low rpm knock under throttle happens because you’re dumping maximum fuel air mixture volume into a cylinder that is still undergoing a relatively slow compression and firing cycle, compared to higher rpm. The slower compression stroke at low rpm gives the mixture more time to predetonate. Higher rpm means the compression stroke happens faster, and before predetonation can occur, the spark plug fires

If it’s lifter noise, ultimately that will likely mean a cyclinder head rebuild. It’s not the piston rings, although in much higher mileage engines, the skirts of the pistons can wear and create piston slap against the cylinder liner. But that’s not what this is. [/quote]

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