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Originally Posted by Ernest72
My thought was that since the rpm’s rarely get above 4k in a highway commute that the ECU could easily compensate for lower octane. I need this car to last as my commuter, so better to be safe or prove it works.
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You could be right. From my understanding the ECU is only looking at knock and will adjust as needed to prevent it. It could also be adjusting the fuel trims, but I'm not sure on that (running richer AFR will help prevent knock). With ECUTEK the 0%-100% factor I talked about earlier is called the "ignition advance multiplier". It would be interesting to log on lower octane. If that multiplier is consistently staying at 100% then I would think the lower octane isn't making any difference.
Quote:
Originally Posted by Ohio Enthusiast
This should throw a code and trigger a MIL (check engine light), no?
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My guess is that there's enough margin in the base ignition table to deal with the lowest octane fuel out there and this would probably never happen. Would be interesting to see some back to back testing comparing octane readings to see how much timing is getting pulled.