First, check for any intake leaks or possible faulty sensors. Tuning should ONLY be done on mechanically healthy motorcycles.
Sensor data is largely dependent on the sensor environment. For example, in some earlier model stock exhausts, the rear sensor is positioned poorly. This ends up causing the cylinder to be leaned out when “tuned”. The standard Harley motorcycle oxygen sensors are also limited by design. The sensor is designed to monitor AFR (lambda) to allow small real time adjustments in high MPG conditions, outside of those conditions, the sensor is unreliable and inaccurate. This is why Direct Links AFR mode using the motorcycles sensors creates a temporary lean condition and target while calibrating steps are taken.
If the motorcycle is connected, click Get ECU Details, then select the restore function under ‘File’. Direct Link should be able to locate the most recent Backup (.ori) file for you. If this doesn’t work, review below for some possible solutions.
Direct Link creates a robust image of the ECUs programming. While it is exceedingly rare that such a thing is actually needed or used, it is very handy to diagnose and isolate possible emerging mechanical issues or just to evaluate the before and after. For a few minutes of patience, you ensure the reversibility of any programming going forward.
This suggests that the engine is getting far too much air. This air could be entering through the throttle plate, IAC, or a rather large intake manifold leak. If it’s not a leak, it might be an indication of a failing IAC (Idle Air Controller). See if the valve needs to be cleaned and make sure the IAC is properly installed.
Could be a result of lean idle conditions. Try increasing VE numbers in the lower RPM area by 10-15 points on either the front or rear VE tables (or both). Program these changes to the ECU and see if the condition has improved.
The Spark@Idle table may be too far off of the MAP based Spark table. Open all 3 spark tables and compare the values. For example, when the throttle is moved on/off its closed position, 30 degrees on the Spark@Idle table may not transition well to or from 12 degrees on the MAP Spark table.
The spark might need to be retarded at idle ranges. Lower the spark table 3-4 degrees in the low rpm 750-1250 – low map 20-30 area. Program these changes to the ECU and see if the condition has improved.