using tuner pro and i dont quite understand number of cyilinders being 192, is this related to timing or somthing similar? engine is a 90 3.1L V6.

 

It is because of how the ECM firmware uses that value. The value 192 is 3/4's of the value 256. With 256 being the proper value to use when it is an 8-cylinder. Although, we can't store the value 256 as a single byte of data.

In the cal, an 8-cyl is set to the value of 0, which lets the firmware know to not do the multiply/divide.

A 4-cylinder uses 128, which is 1/2 of the 8-cylinder value (half the number of cylinders).

This value is used in the conversion of SA from degrees to a time based value. So it is important to have it correct. Has to do with the amount of crank rotation between spark plug firings.

RBob.