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Discussion Starter · #1 ·
Hello all 馃檪
I noticed that sometimes when car is underload I hear like valve sound (metal taping sound) Is it normal or not?
 

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If it's happening under load particularly at low rpm or accelerating from low rpm, it is probably spark knock. It isn't good for the engine however, modern cars tend to run right on the edge of knock and it is not uncommon that they will do it occasionally before the computer pulls ignition timing to prevent damage. If possible, get higher octane fuel and see if it changes/goes away.
 

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Discussion Starter · #5 ·
If it is a detonation then check engine should light up?
Could it be that detonation sensor is faulty and no check engine?
 

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Agreed. Are you running low octane fuel? Try the next one up and see if goes away. Only the price of a tank of gas to see if that's the problem.

How many miles on it? Most likely a sensor.

My car with 160K has never done it.
 
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