What WGDC means (and why your tuner talks about it)
Wastegate duty cycle is the effort behind your boost target. It's the channel that tells you when the turbo has nothing left.
Boost target is a request. WGDC is how hard the turbo is working to grant it — and the gap between the two is where most boost problems announce themselves.
WGDC stands for wastegate duty cycle: the percentage of time the ECU holds the wastegate solenoid energized. It sounds like a sidebar, but it is one of the most useful channels in a log, because it tells you how hard the turbo is straining to hit the boost target you asked for.
The duty-cycle idea
A turbo is driven by exhaust gas. Left unrestricted, it would keep making boost until something gives, so the system vents some exhaust around the turbine through the wastegate to hold a pressure. The ECU controls that vent with a solenoid, and duty cycle is how long per cycle it holds it closed:
- **0% duty** — gate held open. Exhaust bypasses the turbine, and the turbo makes almost no boost.
- **100% duty** — gate held shut. All the exhaust drives the turbine, and the turbo makes everything it can.
- **In between**, the ECU modulates to hold the target. More boost needed, more duty spent.
The turbo's compressor sets the pressure; duty is the throttle on the exhaust that feeds it.
What your tuner is looking for
Low duty at target is healthy headroom — the turbo is barely trying. Duty pegged near its ceiling, or climbing while boost fails to follow, is the signature of a turbo at the end of its range, a target set too high, or a leak. A charge pipe that lets go under boost is the classic: the target keeps climbing, duty goes to 100%, and the actual pressure never arrives.
The everyday version: while you cruise, the gate modulates gently to hold steady manifold pressure. On a pull, duty climbs to spool the turbo quickly, then settles as you approach target. Where duty goes from there — headroom or ceiling — is the story the log tells after the flash.