This is probably an odd ball question as 7747 $42 has been extensively hacked and documented.

My question is regarding Spark Bias - Cold Constant and Coolant Comp Spark table. In the past I always set my Spark Bias - Hot to 0. Then my main SA table reflects uncompensated spark advance actual values. From this value Spark Bias -Cold is subtracted and Coolant comp spark (a two dimensional lookup based on temp and vacuum) is added. There are other modifiers, but they are not relevant to this discussion.

Typical calibrations use Spark Bias - cold = 20.04 which is the base value used in Coolant comp spark at normal operating conditions. What reasonable values can be used Spark Bias - cold i.e. so as long as Coolant comp spark are not negative??? My warm bias is set to 0 and Main SA reflects actual commanded SA.

//RF

 

I prefer to use 10* for the cold bias. This makes it easy to mentally subtract from the compensation table values. And it is rare that more then a -10* SA value is required.

Although, if you have no values in the compensation table that is lower then the bias, then a bias of 0 can be used.

RBob.