"It just feels off" is a fine place to start, but a real data log turns that feeling into something a tuner can actually diagnose instead of guess at.
What A Data Log Actually Captures
A data log records live parameters — boost, EGT, fuel rail pressure, transmission temp, timing, and more — while you drive. Instead of describing a symptom secondhand, it shows exactly what the truck was doing when it happened.
What To Log If You're Not Sure
When in doubt, log broadly: boost, EGT, rail pressure, RPM, throttle position, and transmission temperature at minimum. It's easier to ignore extra data than to realize afterward you didn't capture the one parameter that mattered.
Capture The Moment It Happens
If you're chasing a specific issue — a hesitation, a hard shift, a smoke event — try to have logging running when it happens rather than logging a random errand. A five-minute log that captures the actual event beats a thirty-minute log that doesn't.
Sending It Over
Most logs export as a simple file from your tuning software or app. Send it along with your platform, current mods, and a quick description of what you were noticing, and that's usually enough to point to what's actually going on.