This entry – very short of B38 Rough run data.
As I already mentioned in other entries in connection with other engines/DME – it is essential to clarify basic things of the Rough run menu:
a. order of cylinders (are the data displayed in placement or firing order);
b. data “polarity” – it means an increased value in Rough run data corresponds to the increased or reduced mechanical efficiency of cylinders;
c. “sensitivity” of the menu; it means how significant is the difference from the ideal, created by the value of the exact menu;
d. make sure that the data representation in Call-up menu and Expert modes is identical.
Short report: Rough run menu of ISTA for B38 engine displays the cylinders in placement order; data in Call-up menu and Expert mode are identical.

How the menu looks when the 1st cylinder is disconnected:

a. Rough run data indicate the retardation, it means a positive value means reduced mechanical efficiency of cylinders;
b. a slight data analysis with Excel allows concluding that +/-10% of mechanical efficiency corresponds to around +/-6 units.