Marky Dissod
Full Access Member
If driven hard, if the engine is working or playing hard with 87, the pcm / ecm IS responding to detected knock AFTER IT HAPPENS by pulling timing back, and possibly adding (wasting?) fuel to cool the cylinders.You might not notice a difference but the computer is probably pulling timing back, especially when air temps get hot.
If you don't run the recommended fuel, drive it like your grandmother.
The pcm / ecm NEVER learns this. It never predicts or avoids knock.
It only responds to it quickly enough for y'all to deceive yourselves into saying schidt like
'My 6.2L doesn't knock on 87, regardless of how I drive it.'
Put it on a realtime scanner, learn something new.
This is another way of saying that you're wasting money on 87 instead of using 91.As been said by previous people, you probably won't hear it knocking, unless under a higher load,
but the computer IS dialing back the timing.
Yes, 91 costs more, but MpG would improve by enough to offset the price in most cases.
If not, try E85 - especially if it's at least 25% cheaper than 87.
It has pretty good knock resistance, and you'll get back much of the power lost to 87.
If you can't try E85, and you won't try 89 or 91 octane,
thanks in advance for breaking the engine I was gonna swap into my old Tahoe ...
note: this forum's software redacted something that really did not need redacting.
The redaction policy is more peurile than the thing it tried to redact.
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