Troubleshooting
Most bad shots come down to a handful of causes. The trick is reading the symptom correctly, because the fix for a recipe problem is very different from the fix for a puck-prep problem. Taste first, then change only ONE variable at a time — otherwise you can't tell which change did what.
Quick diagnosis table
| Symptom | Likely cause | Fix |
|---|---|---|
| Sour, sharp, thin | Under-extraction | Grind finer, lengthen ratio, or brew hotter |
| Bitter, harsh, dry | Over-extraction | Grind coarser, shorten ratio, or brew cooler |
| Sour and bitter at once | Channeling | Fix puck prep (see below) |
| Spraying/squirting from bottomless | Channeling | Fix puck prep (see below) |
| Visible holes/craters in the puck | Channeling | Fix puck prep (see below) |
| Shot too fast (< 20s) | Grind too coarse | Grind finer |
| Shot too slow (> 35s) | Grind too fine | Grind coarser |
| Watery, weak | Grind too coarse or ratio too long | Grind finer or reduce yield |
| No crema | Stale beans or grind too coarse | Fresh beans, grind finer |
Under-extraction (sour)
Sour, sharp, and hollow means the water didn't pull enough — it usually ran too fast.
- Grind finer to slow the flow and increase extraction.
- If still sour, lengthen the ratio (pull a little more yield).
- If still sour, raise brew temperature slightly.
Change one lever, re-taste, then decide. Work through it methodically in dialing in.
Over-extraction (bitter)
Bitter, dry, and astringent means the water pulled too much.
- Grind coarser to speed the shot.
- If still bitter, shorten the ratio (pull a shorter yield).
- If still bitter, lower brew temperature slightly.
If you want to understand why these levers work, revisit espresso fundamentals.
Channeling: not a recipe problem
Here is the one that fools people. If a shot tastes sour and bitter at the same time, or you see spraying and squirting from a bottomless portafilter, or there are visible holes in the spent puck, you are not looking at an extraction that needs a grind tweak — you are looking at channeling. Water found a low-resistance path and blasted through it, over-extracting along that channel while under-extracting the rest of the bed. That is why you taste both faults together, and why chasing it with grind changes only makes things worse.
Fix the bed instead:
- Use a WDT tool to break up clumps and even out the grounds before tamping.
- Tamp level and straight down — a tilted tamp leaves a thin edge that channels.
- Don't thump or tap the portafilter after tamping; it cracks the puck.
- Consider adding a puck screen on top of the bed.
The full method is in puck prep.
Shot timing
- Too fast, under ~20 seconds: grind finer and re-pull.
- Too slow, over ~35 seconds: grind coarser and re-pull.
Watery, weak, or no crema
- A thin shot that isn't sour usually means the grind is too coarse or the ratio too long — grind finer or pull a shorter yield.
- No crema at all usually means stale beans (buy fresh, rested a few days off roast) or, again, a grind that is too coarse.
Re-taste after each single change, and lean on dialing in to keep your adjustments disciplined.