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Old 12-14-2011, 07:43 PM   #12 (permalink)
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Most cars in the last couple of decades have automatic idle stabilization with more than enough control authority to keep the idle RPM steady with a small advance in ignition timing like that.

Generally cars are built with safety margins in just about everything important. Spark advance is such a thing--if a car does not have a knock sensor, the timing is almost always set such that even going uphill in Death Valley on a 110 degree day the car will not knock. Advancing the timing can cut into that margin, but under most driving conditions it won't matter.

If a car does have a knock sensor, chances are that it is set up to run much closer to the "ragged edge" where knock occurs. In that case adding static timing will mostly cause the knock sensor to retard the timing more than if it were in the stock position. Which basically gives you no effect from the mod.

I doubt that two degrees' advance will hurt anything in this case.

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