diff --git a/java_console/models/src/com/rusefi/TimeBasedBuffer.java b/java_console/models/src/com/rusefi/TimeBasedBuffer.java
index 081c2f5b03..2ebccbab42 100644
--- a/java_console/models/src/com/rusefi/TimeBasedBuffer.java
+++ b/java_console/models/src/com/rusefi/TimeBasedBuffer.java
@@ -1,4 +1,47 @@
 package com.rusefi;
 
-public class TimeBasedBuffer {
+import java.util.TreeMap;
+
+/**
+ * Last X seconds of values.
+ * <p>
+ * This data structure holds only one value for each millisecond timestamp but that should be totally fine
+ * for our purposes
+ *
+ * @see EtbTestSequence
+ */
+public class TimeBasedBuffer implements DataBuffer {
+    private final TreeMap<Long, Double> values = new TreeMap<>();
+    private final long duration;
+
+    public TimeBasedBuffer(long duration) {
+        this.duration = duration;
+    }
+
+    private synchronized void truncate() {
+        long now = currentTimeMillis();
+        values.headMap(now - duration).clear();
+    }
+
+    protected long currentTimeMillis() {
+        return System.currentTimeMillis();
+    }
+
+    public synchronized void add(double value) {
+        values.put(currentTimeMillis(), value);
+    }
+
+    public synchronized int getSize() {
+        truncate();
+        return values.size();
+    }
+
+    public synchronized double[] getValues() {
+        truncate();
+        double[] result = new double[values.size()];
+        int i = 0;
+        for (Double v : values.values())
+            result[i++] = v;
+        return result;
+    }
 }
diff --git a/java_console/models/src/com/rusefi/test/TimeBasedBufferTest.java b/java_console/models/src/com/rusefi/test/TimeBasedBufferTest.java
index 926a7fefd2..03661daca2 100644
--- a/java_console/models/src/com/rusefi/test/TimeBasedBufferTest.java
+++ b/java_console/models/src/com/rusefi/test/TimeBasedBufferTest.java
@@ -1,4 +1,51 @@
 package com.rusefi.test;
 
+import com.rusefi.DataBuffer;
+import com.rusefi.TimeBasedBuffer;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 public class TimeBasedBufferTest {
+    @Test
+    public void testRealTruncate() throws InterruptedException {
+        TimeBasedBuffer b = new TimeBasedBuffer(100);
+        b.add(1);
+        System.out.println(b.getSize()); // cannot really test size here since who know how time flies
+        b.add(2);
+        b.add(1);
+        System.out.println(b.getSize()); // cannot really test size here since who know how time flies
+        Thread.sleep(200);
+        assertEquals(0, b.getSize());
+    }
+
+    @Test
+    public void testTruncate() {
+        AtomicLong time = new AtomicLong();
+        TimeBasedBuffer b = new TimeBasedBuffer(100) {
+            @Override
+            protected long currentTimeMillis() {
+                return time.get();
+            }
+        };
+
+        b.add(1);
+        assertEquals(1, b.getSize());
+        b.add(2);
+        assertEquals(1, b.getSize()); // value for same timestamp is overriden
+        time.set(3);
+        b.add(3);
+        assertEquals(2, b.getSize()); // value for same timestamp is overriden
+        double[] v = b.getValues();
+        assertTrue(Arrays.equals(new double[]{2, 3}, v));
+
+        assertEquals(0.707106, DataBuffer.getStandardDeviation(b.getValues()), 0.001);
+
+        time.set(150);
+        assertEquals(0, b.getSize());
+    }
 }
diff --git a/java_console/ui/src/com/rusefi/ui/widgets/EtbTestSequence.java b/java_console/ui/src/com/rusefi/ui/widgets/EtbTestSequence.java
index 40a1964dbb..a735b14eeb 100644
--- a/java_console/ui/src/com/rusefi/ui/widgets/EtbTestSequence.java
+++ b/java_console/ui/src/com/rusefi/ui/widgets/EtbTestSequence.java
@@ -2,6 +2,7 @@ package com.rusefi.ui.widgets;
 
 import com.rusefi.FileLog;
 import com.rusefi.SensorSnifferCentral;
+import com.rusefi.TimeBasedBuffer;
 import com.rusefi.core.Sensor;
 import com.rusefi.core.SensorCentral;
 import com.rusefi.io.CommandQueue;
@@ -19,6 +20,8 @@ import java.util.concurrent.TimeUnit;
  * <p>
  * 11/16/2017
  * (c) Andrey Belomutskiy
+ *
+ * @see TimeBasedBuffer
  */
 public class EtbTestSequence {
     private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();