What it does
When engine speed falls to a set RPM, Stall Saver turns on an output. That output typically drives a solenoid valve or a throttle kicker that lets more air in, lifting RPM enough to keep the engine running. Think of a lightweight flywheel car dropping off a clutch, or a race engine with a big cam that dips hard on decel.
These days most setups use proper idle control, which now includes stall saving itself. Stall Saver as a separate function is mainly for older builds or engines with only an on/off air valve.
Setting it up in ESP
Wiring tab
- Stall Saver Output: choose a free output for the valve or kicker, usually a DPO (Digital Pulsed Output) or a stepper output.
- Active State: Low (the default) grounds the output wire when Stall Saver is on. High flips that: the wire is grounded when the function is off and released when it's on. Use High only if your valve works the inverted way.
Stall Saver tab
- On Value: the RPM at which the output turns on.
Choosing the On Value
Set it below your normal idle so it never fights the idle speed, but high enough that the extra air arrives before the engine dies. We start a little below target idle and then test by blipping and releasing the throttle, and by stalling on purpose with the clutch. Watch RPM in the log: if it still dies, raise the On Value; if the valve clicks on during normal idle, lower it.
Outputs switch to ground, so the valve's other terminal needs switched 12 V. Keep valve current within the output's rating, and use a relay for anything heavier.
Common questions
Do I need Stall Saver if I have idle control?
Usually not. Idle control already covers it, and running both can make them fight over RPM.
My valve works backwards. What do I change?
Set Active State to High.
Related: decel fuel cut, torque model and the Nexus version of Stall Saver.
