Cars engine rpm

Projects General Guidance
6

brunokc:
Hallo

im looking for a way to pull a Cars engine rpm in to the arduino the simplest and fastest way.

any one know what that is?

What is your goal of the system? Do you want the arduino to determine RPM and display that data to the driver or are you trying to drive fuel injectors and need to know crank position? Does the arduino need to do more things computationally?

If I were tackling this problem and assuming that I do not need to know crank position I would do one of the following with my sensors:

  1. Use a hall sensor. Not an option in your case.
  2. Make a little bracket that holds an IR led and IR sensor and place a piece of reflective duct tape on the harmonic balancer or crank.
  3. Gut a timing inductive light and measure the spark. This would not be consistent when the engine changes state as you increase your spark advance. With proper post processing, this could be made to work. You will have to factor in that sparks would only occur every 720 degrees unless you are using wasted spark.

I have used #2 when I had an encoder break. I know there are some OBDII solutions. Again, I would like to know your goals? Fun? or Data? What are you doing with the data?

Software:

  1. Use some type of box filter that averages several samples and updates the display about every second.