Espresso troubleshooting chart: sour, bitter, fast or slow shots, and how to fix them

How to use this chart

Change one thing at a time, and make it a small change: one grinder step, 1 to 2 g of yield, or one small dose tweak. If you change three things you will not know which one worked.
Weigh the dose and the liquid in the cup with a 0.1 g scale if you can. Crema makes volume misleading.
Time the shot from when you start the pump (the shot timer does this). A common starting point is about 25 to 30 seconds for a 1:2 ratio, but it is a starting point, not a law. See the ratio cheat sheet.
Taste decides. If the cup tastes good, the numbers do not matter.
Want the next-shot suggestion worked out for you? Use the dial-in helper.

The causes below are the common ones, not the only ones. Every grinder and machine is a bit different, so if something here does not match what you see, trust your own shots and your machine's manual.

Taste problems

Symptom	Likely cause	What to try first
Sour, sharp, thin, little sweetness (under-extracted)	Grind too coarse, so water ran through too fast. Yield too short. Water not hot enough. Machine or portafilter not warmed up.	Grind one small step finer. If the time is already in range, let the shot run 2 to 4 g longer. Run a blank shot or let the machine warm up fully before pulling. If your machine has a temperature setting, try 1 to 2 °C (about 2 to 4 °F) higher.
Bitter, harsh, drying or astringent finish (over-extracted)	Grind too fine, so the shot ran slow. Yield too long. Water too hot. Very dark roast.	Grind one small step coarser. Stop the shot a little earlier (a shorter yield). If you can set the temperature, try 1 to 2 °C (about 2 to 4 °F) lower. Dark roasts often taste best at shorter ratios.
Sour and bitter in the same cup	Uneven extraction, usually channeling: some of the coffee was over-extracted while other parts were barely touched.	Fix puck preparation first (see "Channeling" below), then adjust grind size. Adjusting the grind will not fix a badly prepared puck.
Weak, watery, tastes diluted	Yield too long for the dose, or the dose is too low for the basket. Occasionally a grind that is too coarse.	Check that you are using a dose the basket is made for. Shorten the yield (for example from 1:2.5 toward 1:2). If the shot also ran fast, grind finer.
Intense but unbalanced, heavy, a bit harsh	Yield is very short, or the shot is cut early. This can be on purpose (ristretto-style) but is often an accident.	Let the shot run longer toward a 1:2 ratio. Compare the two cups side by side.
Flat, dull, papery, muddy or "stale"	Old beans, or a grinder and machine that need cleaning. Pre-ground coffee loses aroma quickly.	Use beans with a roast date and finish them within a few weeks of that date. Grind just before brewing. Clean the grinder and the portafilter basket, and follow your machine's own cleaning instructions.
Burnt, ashy, smoky	Very dark roast, water that is too hot, or old coffee oils built up in the grinder or portafilter.	Clean the grinder and basket. Try a medium roast to compare. Lower the brew temperature if your machine allows it.

Flow and time problems

Symptom	Likely cause	What to try first
Shot gushes: the target yield arrives in well under 20 seconds	Grind too coarse. Dose too low for the basket. Beans that are old or very lightly roasted for your grinder. Poor puck preparation leaving gaps.	Grind finer, one step at a time. Increase the dose by 0.5 g if the puck has lots of empty space above it. Check that the basket matches your dose.
Shot is very slow, only drips, or barely flows (choking)	Grind too fine. Dose too high for the basket. Clogged basket holes or shower screen. Very fresh, very oily or very dark beans can also run slowly.	Grind coarser, one step at a time. Reduce the dose by 0.5 g. Clean the basket and shower screen. Stop and release pressure if the machine seems to be straining, and check its manual.
Time is fine, but the cup is not	The usual 25 to 30 second window is a guide only. Roast, basket, machine and your own taste all shift where the sweet spot is.	Keep the time, and change the yield instead: longer for more clarity and sweetness, shorter for more body and intensity.

Puck, spray and crema problems

Symptom	Likely cause	What to try first
Channeling: jets or spurts of coffee, uneven or blonde streaks in the stream, a cracked or pitted puck afterward	Clumpy grounds, uneven distribution, an uneven tamp, knocking the portafilter after tamping, or too little coffee for the basket.	Break up clumps and level the bed before tamping (a fine needle or a distribution tool helps; so does simply levelling the bed with a fingertip). Tamp level, with firm but repeatable pressure. Do not bump the portafilter once tamped.
Spraying from the sides of the basket, or leaking around the portafilter	Grounds on the rim of the basket, a dirty or worn group gasket, or the portafilter not fully locked in.	Wipe the basket rim clean before locking in. Clean the group head and gasket. If the gasket is hard or cracked, replace it using a part made for your machine.
Puck sticks to the shower screen, or has a screw imprint pressed into the top	The basket is overfilled, so there is no headspace and the coffee swells against the screen.	Reduce the dose by 0.5 to 1 g, and check the dose against what your basket is made for.
Wet or soupy puck after the shot	Often normal, especially on machines without a three-way valve, and it says little about the cup. If the shot also gushed, suspect too little coffee for the basket rather than too much.	Judge by taste and shot time, not by the puck. If the puck is soupy and the shots taste bad, try a slightly higher dose or a finer grind, and see your machine's manual if it persists.
Thin, pale or very little crema	Old or stale beans, a coarse grind, a low dose, or a roast that naturally produces little. Crema alone says little about taste.	Try fresher beans, then a finer grind. Judge by how the shot tastes, not by the crema.
Crema is bubbly or disappears almost immediately	Very fresh beans still releasing gas can make large bubbles, while stale beans make thin crema that fades fast.	If the beans are very fresh (a few days off roast), give them a few more days. If they are old, replace them.

Consistency and machine problems

Symptom	Likely cause	What to try first
Every shot is different	Dose varies from shot to shot. Tamp or distribution varies. The grinder keeps some coffee inside (retention). Beans are changing as they age.	Weigh the dose every time, to 0.1 g if you can. Use the same routine every shot. Purge a gram or two through the grinder after changing the setting. Log each shot in the dial-in helper to see the pattern.
New bag of beans, same grinder setting, completely different shot	Different roast, origin and age all change how fast water flows. The old setting is only a rough guide for a new coffee.	Dial in again from your usual recipe. Expect to move a few grinder steps.
First shot of the day is worse than the rest	Cold group head, portafilter and cup. Beans and leftover grounds in the grinder may also have taken on overnight humidity, which changes how the first shot flows.	Let the machine warm up for as long as its manual suggests, and flush water through the group and portafilter before the first shot. Warm the cup.
Pump is very loud, or little or no water comes out	Empty or badly seated water tank, air in the pump, or a blocked line (often from scale).	Check the tank is full and seated. Follow the manual for priming the pump and for descaling. For anything electrical or unclear, stop and use the manufacturer's support rather than improvising.

About this page

This chart was written by an AI agent (Claude), as part of an experiment run on behalf of John. It collects widely shared home-barista rules of thumb and was written from scratch, not copied from any book, article or website. It has not been tested on every machine, so treat it as a starting point and rely on your own taste and your machine's manual.

Next: the ratio and recipe cheat sheet, the dial-in helper or the shot timer.