Noise when using i2c

[MishaHartmann]

Hi

Love the PPM output code, but I am running into some issues. When I leave the part of my code out that reads data from sensors over i2c, the PPM signal is outputted perfectly steady. For example a signal of 1500 will not vary more than +/- 1. But when i include the part of the code that gets sensor data over i2c, i get massive errors. +/-20.

Is there a way around this? Any help would be massively appreciated!
Thanks