What causes boost to cycle
 

Sometimes my boost will not hold on full, it keeps cycling up and down, only by about 0.3 bar.
Most of the time it will be steady, but every now and then this happens.

Any ideas?

MY01WRX JDM with full decat and ECU-TEC
Thanks, Rob.

Have the same prblem with mine (MY00). I got a TEK2 second-hand, and when I spoke to Power Engineering a couple of days ago they said I need to open out the restrictor in the vacuum pipe to around 1.25mm otherwise if the ecu sees a boost above target it cuts the boost then goes into the cycling mode you describe. Not sure if MY01 is the same setup. PE recommended opening up the restrictor then doing a reset.

Graham

do you need the restrictor when using a gems ecu, or can I just remove the restrictor and run the pipes direct.

cheers