Problem with reading RPM (pulses) from car ECU

Hi, i looking for code to reading/counting rpm pulses from car ecu, i want build lunch control device but in first place i need read rpms, next cut spark when reach set limit and the last place make menu in arduino lcd shield with options. I have some code but when i run arduino it show 9000rpm and drop to 300 rpm ±20 when it’s only connected to usb when i connect to car ecu it show 305rpm and don’t change ???

PablosVXZ: Hi, i looking for code to reading/counting rpm pulses from car ecu, i want build lunch control device but in first place i need read rpms, next cut spark when reach set limit and the last place make menu in arduino lcd shield with options. I have some code but when i run arduino it show 9000rpm and drop to 300 rpm +-20 when it's only connected to usb when i connect to car ecu it show 305rpm and don't change ???

This is not an appropriate post in the section of the forum for THE Arduino project.

Click on Report to Moderator in your post, and ask that it be moved to Project Guidance.

I have some code but

you are not going to share it.

it show 305rpm and don't change ???

Is that a question? The answer is no, that is not what the code you didn't post does. That's what my crystal call says.