Quote:
Originally Posted by richard s
On lower octane we call this pinking. My old car runs better on higher octane.
Bosch Super 4 spark plugs, Piper box air-filter, Splitfire HT leads really improves MPG and Power output.
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Modern cars will deal with knock providing you use at least the manufacturer's minimum recommended fuel grade. You can actually induce knock yourself based on they way you drive and it's the job of the knock sensor to report this to the ECU and make the relevant adjustment to the timing advance.
Fuel that doesn't combust properly because it's loaded with crappy additives is another matter and BP "Ultimate" is very, very bad inparticular. Basically do not use it if you have a Subaru, Evo or anything of that ilk which is tuned as the tolerances around what these cars will run efficiently on can be quite narrow.
This dodgy juice can mess up the fuel trim as it tries to maintain the magic 14.7:1 fuel/air ratio and there will be a tendency for the ECU to significantly over-fuel so you can say goodbye to whatever MPG you have and a decent amount of boost pressure when everything else including the timing gets knocked out of balance.