Quote:
Originally posted by DaveDatsun:
Some ECU's have knock sensors and will alter the timing to prevent damage due to a low octane tank of gas. Don't know if the X has this system.


Yes it does. Unfortunately, it's in a stupid spot. It's under the intake manifold and I don't think you can get at it without removing the intake. Oh well, hopefully you never have to replace it. As far as I know, all modern engines, meaning computer controlled, have a knock sensor. Because computer controlled engines are capable of controlling fuel and spark for optimum efficiency they also have to have a way to know where optimum is. Older mechanical/vacuum controlled spark advance methods obviously didn't require one.

Great explanation of timing by the way!
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