- Mon Mar 22, 2010 7:08 pm
#182906
Turning your distributor sets the BASE ignition timing. The ECU trusts you to set the base timing to the spec that is on the emissions sticker under your hood. From there it adjusts the ignition timing to whatever it wants. For instance, it fluctuates the ignition timing to keep the idle smooth, advancing it if the RPMs drop from the rad fan, PS sensor input, ELD input etc. Dropping it if the idle is too high. Above idle the ECU refers to a predetermined ignition map to add or subtract timing from the base timing.
Messing with the base timing does nothing for performance. There is no blanket adjustment you can make to the entire calibration to increase power. If you advance the entire ignition timing, you MAY gain power in some RPM / load cells (referring to the calibration fuel and ignition tables) but you will lose power in others. It's the same thing as an adjustable FPR. Foolhardy.
In some cells, reducing timing increases power, and in others, increasing it increases power. If you ignite the fuel mixture too soon, the flame front will fight the piston on it's way up. If you start it too late, the piston will already be on it's way down and the flame front will chase after it. The best example is to push someone on a swing. Advancing the timing too far is the same as pushing the person when the swing is still coming backward. You will drastically slow them down. If they knock you on your ass that is analogous to pushing your piston out the side of your block. Which CAN and DOES happen. You need to push them at the perfect moment, but with an engine a dyno is the only reliable and effective way to find just when that is.
Blindly advancing your base timing will increase the risk of detonation, increase your emissions output, you could lose fuel economy, decrease power, and reduce the life on the engine. You need a load-bearing dyno and a competent tuner to go into groups of connected cells and adjust the timing up or down to find the best torque that doesn't put your engine at risk.