Hondata

When I try to datalog and record to the flashpro unit while cranking it stops datalogging as I crank. If I record to the laptop it is fine.
Is there a solution?

Your battery voltage is to low when cranking more than likely.

Possibly. My car was standing for 4 weeks but I have done a lot of driving the last few days so it should be charged well.

I have also relocated it to the trunk but the cable thickness is enough.

I noticed the power led on the flashpro flashes off/on once when I crank.

The problem is that you have relocated the battery. This causes a decrease in voltage.