diff --git a/examples/MQ-4/MQ-4.ino b/examples/MQ-4/MQ-4.ino
index de75854..d8aa02d 100644
--- a/examples/MQ-4/MQ-4.ino
+++ b/examples/MQ-4/MQ-4.ino
@@ -49,4 +49,5 @@ void loop() {
   //int lecture =  MQ4.readSensor("CO", true); // Return CO concentration
   //int lecture =  MQ4.readSensor("Alcohol", true); // Return Alcohol concentration
   //int lecture =  MQ4.readSensor("smoke", true); // Return smoke concentration
+  delay(400);
 }