Find peaks between peaks (from other signal)

Hello

I'm doing project on an engine. In the attachments there is an image of the signals that I'm using from the motor.

The N_signal is a signal that tells me when the engine has made one rotation. The Spark signal is an signal that tells me when the spark takes place.

The distance between the N_signals is always the same (if the engine remains at a certain speed).

The problem is that when the speed of the engine increases, my sample rate isn't high enough so I loose part of my original signal.

For example: I loose certain peaks of the spark signal or the N_signal.

My goal with this signals is to measure the peaks from spark that are between two good (not lost) N_signals.

Has anyone an idea what I can use for this.

With Regards Hans Vertongen

[CS Researcher]

Can you increase the sampling rate? If no, is it necessary to increase the speed of the engine?