DHT 11 sensor I use cause my MQ3 sensor to spike. So I tried a few tests, it seems every time the arduino does the:
My MQ3 signal spikes.
So if I change the frequency these two lines happen, the spike would change to those frequencies.
If I remove these two lines from happening or simply pull out the wire for the DHT 11 sensor (return nan), the spike stop.
Don't know why it happens. I mean I could just make the MQ sensor skip those readings, but I want to know why.