I have a 2001 Toyota Corolla, and under acceleration I get a sound that sounds like loose bolts under the hood. If I accelerate slower, then the sound goes away. I can't get it to do it in park, and I have heard this sound on an older toyota truck I used to have. I heard that it could be pinging, but am not sure. Any ideas?
Thanks,
CP
When you say noise only under acceleration - as in WOT or just more than 50% throttle? When you say accelerate slower - how much throttle are you using? Can you describe the sound in more detail - metallic sound, low/high pitch, frequency?
Since you cannot reproduce the sound in park - this sounds like it is related to engine load. Could be anything from a worn belt tensioner - those can make a good amount of noise when they weaken over time, to an issue with the VVTi system, in particular the oil control valve and OCV filter, to a bad tank of gasoline, worn plugs (misfire), leak or obstruction in intake or exhaust system, etc.
friendly_jacek
Sounds like he is describing pinging. However, Fish you are correct as I had similar noise with bad belt tensioner.
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