My setup is Ardupilot 2.6, IMU, Ublox, Xbee pro 900 mhz, kyosho calmato 60 sport trainer (aprox 8 lb) 4 stroke saito 100 and 24 oz fuel tank. previosly I been flying with IR sensors (ardupilot 2.4) everything were ok, since I've changed to IMU things get messy, basicaly the IMU is affected by engine vibrations, I 've tried different shock absorbers but they didnt help, any attempt to run the engine above 5000rpm will cause IMU health drop to 0. in the IMU manual I find the gyro adjustments, can I reduce the shock sensibility through Gyro_gains ?
Also is your prop balanced? Are you mounting your engine with shock absorbers as well?
"The new quad-sensor design rejects the influence of linear acceleration, enabling the ADXRS450 to operate in exceedingly harsh environments where shock and vibration are present and can cause measurement errors in less capable gyros. The ADXRS450 is the most stable, vibration-immune MEMS gyro available, with sensitivity to linear acceleration specified at only 0.03 °/sec/g, acceleration rectification of only 0.003 °/sec/g2, a noise-rate density specification of 0.020°/sec/√Hz, and power consumption of only 6 milliamps under typical conditions. Other features include internal temperature compensation over an extended industrial temperature range and an optional ceramic vertical-mount package that uniquely enables three-axis sensing on a single PCB without daughterboards."