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Old 10-27-2018, 03:04 AM   #21
Scooby Specialist
Member#: 460907
Join Date: Jan 2017
Chapter/Region: RMIC
Location: Colorado
2016 WRX



If you're running 91 octane gas and you start getting knock, then you raise your octane (via torco or xylene) to 93 and you don't get knock anymore, then it's likely the tune was too aggressive or there is a mechanical issue with your motor. Octane = measurement of a fuel's resistance to knocking. So if you add more octane and the knock goes away then that was likely the problem.

If in the same situation, you're running 91 and you start getting knock, then you raise your octane and you still get knock, then it's likely not an octane or mechanical issue but likely false knock. If it was due to aggressive tuning or a mechanical problem then raising the octane would mitigate it. If it's a problem like a heat shield rattling, then no matter how high you raise your octane rating it won't matter because it's the noise of the rattle setting off the knock correction not actual knock.That would be false knock.

Obviously this isn't 100% fool-proof, just because you add torco and the car still knocks doesn't mean it's definitely false, the tune could still be too aggressive or something. But this is an easy way to check without ripping your engine apart.
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Last edited by GlarryHoodDIT; 10-27-2018 at 03:10 AM.
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