air temp compensation table filling

Hi,

In case your air temp compensation table has two option one for fuel and one for ign. Each table has two axes with one with volts from sensor 0 to 5 and the othe fuel from -30% to 30 % and the other table for the ignition with in one axes the sensor voltage and the other the crank degree from -10 to 10.

How you can start to fill?

First, pick the "normal condition" temperature. That's somewhere between 20C and 40C. It depends where the sensor is located too (in the air box, or in the intake manifold, or some other place). Usually the normal condition has 0 correction.

Then for spark, it's easier. You want to retard spark timing with higher temperature. So maybe 0 correction between 20C and 40C, and then -2C at 50C, -4C at 60C, or something like that. It depends how sensitive the engine is to knock.

For fuel, you still have a "0" area. Generally, you want to enrich when it is colder and lean out when it is warmer. However the compensation will depend on where the sensor is located, how fast it responds, and how hot it gets under the hood. You can try to maintain a constant AFR throughout most of the temperature range or you can try to make it go richer when it is too cold or too hot. If you have closed loop O2 control it is a little less important to get this table "perfect" because the o2 sensor (wideband o2 hopefully) will make up for inaccuracies. You have to be careful of heat soaking, where you stop the engine at 30C air temp and then 10 minutes later start up at 70C due to 35C ambient temperature outside.