Quote Originally Posted by 1project2many View Post
OBDI Saturns used MAF but agan, where to find a definition file?

The $58 code (it's really the same code, I4 or V6) has a few cool things built in. For example, if knock doesn't stop when timing is retarded, the ecm is programmed to add fuel then to reduce boost. And the ecm will control the boost control valve. I don't know of a MAF ecm for four cylinder that will do that.

The values to change are max advance, max retard, and reference angle. It's simple but not... Many definition files out there have the wrong conversions. And you want to know whether or not you're using a crank with the notches 10 degrees advanced, which would change the reference angle from 60 deg to 70 deg. If you have the correct stock calibration for your car I could likely pull the limits out of the file.
I have gone the less DIY route and use Tunercat. He does not list a definition file for Saturns but he may have one. I'll check

Tunercat has a $58 defintion file for 6 cylinders and a $58A definition file for 4 cylinder so there has to be a difference in where the data is located or how it is scaled

The $58A AKDB calibration for a Sunbird has the following:
-spark reference angle = 6
-max advance relative to reference = 54.14
-max retard relative to reference = -5.98

The $A8 AXRM for a 2.3L W41 Quad 4 has the following:
-spark reference angle = 74.9
-max advance relative to TDC = 60.1
-max retard relative to TDC = -9.8

Curious that different references points are used. I guess that the 6 degree spark reference angle on the Sunbird is the spec for setting base timing with the distributor. The ECM needs to know this to compare the total timing to limits. So the max total timing limit for the Sunbird is 6 + 54.14 = 60.14 degrees BTDC and the minimum total timing is 6 -5.98 = 0.02 BTDC as compared to 60.1 and -9.8 for the Quad 4. Now if the spark reference angle is changed to 74.9 degrees to account for the reluctor notch location then the max advance and retard need to be adjusted by 74.9 - 6 = 68.6 degrees and the value for the Quad 4 max advance become 60.1 - 68.6 = -8.5 and the max retard becomes -9.8 - 68.6 = -78.4. Have I got this right?

Next step is to look at wiring diagrams and see how the ignitions are wired to the ECM's for a distributor vs a DIS system