[xXManwhoreXx]

Fuel is the most important. For the tuning of the fuel, the ignition timing should be set at the factory setting (16 degrees before TODC). There is a ratio of what we call Air/Fuel mixture. This is the ratio of how many parts of air there are vs how many parts of fuel there are or as a lambda value. The lambda value is derived from the stoichiometric air/fuel ratio, which is the chemically correct ratio of air to fuel for complete combustion to take place. The stoichiometric ratio is 14.7:1 when expressed as an air/fuel ratio, or 1 when expressed as a lambda value. A richer mixture will have a lower air/fuel ratio and lower lambda value. e.g. an air/fuel ratio of 13:1 equals a lambda value of 0.88, and is a typical value for a naturally aspirated engine under full load. Boosted engines need to run a little more rich that NA ones. When tuning you should set it to run rich first then lean the mixture out till you start gaining power. Once you stop gaining power, increase the mixture a little bit to the rich side to give yourself a margin for error. Then, look at the dyno chart and adjust the mixture at the rpm where you have dips in power.

Tuning of the ignition timing is the second major thing that should be adjusted. Like mixture, at first it is best to adjust the whole of the ignition table. There are many strategies when tuning ignition timing, but one which works on nearly all engines is to simply advance or retard the whole ignition table 2 degrees and perform a dyno run. The tuner should keep a close watch on the Knock sensor output to insure that detonation is not setting in when the ignition timing is advanced. If the torque curve moves upwards, keep adding ignition timing until there are no power gains. If the torque curve moves downwards, then apply the opposite change to the ignition table. When retarding the timing the tuner should keep a close watch on the Exhaust gas tempature. You should find a point where adding or subtracting 1-2 degrees timing will make very little difference to the torque curve. Once this is completed the tuner should look for dips in power again and adjust the timing at that rpm.

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