Editing S130/afmrefresh php (section)

=== Flapper Door Tension Adjustment ===

This modification can improve throttle response by reducing the force needed to open the flapper door, but it can also negatively affect performance if done without an '''air/fuel gauge'''.
The AFM’s spring tension is factory-calibrated, and changing it alters the air/fuel mixture except at wide-open throttle (WOT). At WOT, the flapper door is fully open, so spring tension no longer matters.

===== What the Adjustments Do: =====

-
'''Lightening Spring Tension:'''Richens the mixture. Less force is required to open the flapper door, so the ECU thinks more air is entering and adds extra fuel — resulting in a richer mixture. -
'''Strengthening Spring Tension:'''Leans the mixture. More force is required to open the door, so the ECU thinks less air is entering and adds less fuel — resulting in a leaner mixture. WARNING: Never lean the mixture below factory settings without an A/F gauge. Lean conditions can cause severe engine damage.

===== Tools Needed: =====

* Phillips screwdriver
* Permanent marker

First, make '''two reference marks''' with your permanent marker — one on each side of the tension spring retainer. This will allow you to return to the factory setting if needed.

https://dev.z31library.com/xenonzcar_archive/s130/images/tension_adjustment.jpg

===== Adjustment Steps: =====

* Break the retainer screw loose (may have glue from the factory), but do not fully loosen it yet.
* Secure the tension spring cog in place — never let it spin freely or the spring will unwind completely.
* Loosen the retainer screw enough so the cog can turn.
-
'''To lighten tension:'''Let the cog turn itself slowly.'''To tighten tension:'''Turn the cog against the spring force. - Tighten the retainer screw once the desired adjustment is made.
* Check air/fuel ratio at different RPMs to confirm proper tuning.
* Seal up the AFM once satisfied.

Done correctly, this adjustment can improve driveability, but proceed with caution — incorrect settings can harm performance or engine health.

[[Category:Imported from Xenonzcar]]