We used to have to start car engines by key and listen for when the engine would “catch”. How does it know now automatically?

Question

This is probably already revealing how old some of us are, but we remember that we had to start our cars by turning the key and waiting to hear the engine “catch”. At that point you knew the engine was ok to proceed, and if you stopped turning the key it wouldn’t die.

How does the starter today (push button) know all this, and it never seems to get it wrong? I have never heard a push button starter fail to get it right unless some other issue like dead battery, etc. (and btw, today’s engines seem to have so far fewer issues like we used to have)

In: Engineering

Answer 1

Tach signal.

I left this simple but accurate answer but apparently it lacked enough words to be accepted.

There’s a signal from the engine called tach signal. Remote starters use it to know when to stop cranking. Push button starters will use the same signal. There’s lots of different data streams in a modern engine but tach signal will be the one used for the scenario in your question.