How do you find a stable idle on a cammed LS?

HP Academy's order of operations (HP Tuners, GM computers):

1. Set a realistic idle target for the cam. HPA suggests 550–600 rpm stock and about 800–850 rpm for an aggressive cam (around 240° at 0.050"), with up to about 950 rpm cold on modified engines. LSX Magazine gives similar figures: 525–550 stock, 750–850 for a performance cam.
2. Get fuel and spark right first. Idle tables can't fix a wrong air-fuel ratio. A big cam lowers volumetric efficiency at low rpm, so the stock idle-region VE values are wrong after a cam swap.
3. Let the computer open the throttle enough. The idle "percentage max" setting is about 2% stock; HPA raises it to 4% or more for aggressive cams.
4. Fill in base running airflow from logs. Log actual airflow at idle across coolant temperatures (the VCM Scanner histogram), then add 1–2 g/s so rpm doesn't dip. For big cams the minimum airflow in the 600–1,000 rpm range can need up to about 50% more.
5. Calm the adaptive spark. The overspeed/underspeed spark tables add or pull timing to hold idle; HPA halves the factory values on modified engines.

HPA's caveat: don't drill holes in the throttle plate — fix it in the software.

See cam tuning.

Want to do it yourself? See who tunes it, and how to learn.