Troubleshooting Guide
Inconsistent Shot Times
Diagnose why identical prep produces different extraction times. Systematic troubleshooting flowchart.
Diagnose why identical prep produces different extraction times. Systematic troubleshooting flowchart.
Inconsistent shot times indicate something is changing between shots. Same grind, dose, and tamp should produce similar extraction times. When they don't, something is wrong.
This guide helps you systematically identify the cause and fix it.
✓ Common Causes:
Follow this flowchart to identify the cause of inconsistent shot times.
Pull 5 consecutive shots with identical prep (same grind setting, dose, tamp). Time each shot from pump start to finish.
Record Times:
Shot 1: ___ seconds
Shot 2: ___ seconds
Shot 3: ___ seconds
Shot 4: ___ seconds
Shot 5: ___ seconds
Proceed to Step 2
Calculate the difference between fastest and slowest shot.
Variance = Slowest - Fastest
Example: 28 sec - 22 sec = 6 second variance
🟢 Acceptable Variance: 0-2 seconds
Normal variation. Likely humidity or minor grinder drift. No action needed.
🟡 Concerning Variance: 2-5 seconds
Indicates a problem. Proceed to Step 3.
🔴 Severe Variance: 5+ seconds
Major problem. Proceed to Step 3 urgently.
Buy a cheap hygrometer ($10). Measure room humidity.
Humidity Check:
If humidity changed since yesterday, that's likely the cause. Humidity affects coffee moisture content, which affects grind consistency.
Action:
If humidity is high (>60%), use WDT. If humidity is low (<30%), use RDT. This compensates for humidity effects.
If humidity is stable, proceed to Step 4
Grinder drift means the grind setting shifts slightly between shots.
Test for Drift:
If Drift Detected:
Tighten the burr carrier or grinder adjustment mechanism. Check manufacturer instructions. Some grinders have loose adjustment mechanisms.
If no drift, proceed to Step 5
Burr wobble means the burrs aren't perfectly aligned, causing uneven grinding.
Test for Wobble:
If Wobble Detected:
Tighten the burr carrier mounting bolts. Check for worn bearings. May need professional service or burr replacement.
If no wobble, proceed to Step 6
If grinder is fine, the problem is likely the machine.
Check For:
Action:
Descale the machine. Replace gasket if worn. Clean shower screen. These should resolve most inconsistency issues.
Symptom: Grind setting moves between shots. Shot times vary widely.
Cause: Loose adjustment mechanism or worn threads.
Solution: Tighten adjustment mechanism. Check for worn parts. May need replacement.
Difficulty: Easy to moderate. Check manufacturer instructions.
Symptom: Burr carrier moves when you try to wiggle it. Inconsistent grind.
Cause: Loose mounting bolts or worn bearings.
Solution: Tighten mounting bolts. If wobble persists, burrs may be worn and need replacement.
Difficulty: Moderate. May need professional service.
Symptom: Shot times vary day-to-day but are consistent within a day.
Cause: Room humidity affects coffee moisture content, which affects grind consistency.
Solution: Use WDT (high humidity) or RDT (low humidity) to compensate. Store beans in airtight containers.
Difficulty: Easy. Just adjust technique.
Symptom: Shot times gradually get slower. Water flow seems uneven.
Cause: Mineral deposits in group head cause uneven water distribution.
Solution: Descale the machine. Use filtered water to prevent recurrence.
Difficulty: Easy. Follow descaling procedure.
Symptom: Water leaks around portafilter. Shot times vary. Extraction is inconsistent.
Cause: Gasket is worn or damaged, allowing water to escape.
Solution: Replace gasket. Cost: $5-15. DIY friendly for most machines.
Difficulty: Easy. 5-10 minutes.
Symptom: Water flows unevenly through group head. Channeling visible in puck.
Cause: Scale or debris clogs shower screen holes.
Solution: Clean or replace shower screen. Cost: $3-8. Takes 2 minutes.
Difficulty: Very easy.
Variance 0-2 seconds: Normal. No action needed.
Variance 2-5 seconds: Check humidity first. Then check grinder drift.
Variance 5+ seconds: Check machine (scale, gasket, screen). Then check grinder.
Variance getting worse over time: Likely scale buildup. Descale immediately.
Inconsistent shot times are fixable. Follow this flowchart to identify the cause and take action.
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