D180/Jabiru RPM fluctuations

[johnd]

I've got a D180 with a Jabiru 3300 and an picking up the Tach from the alternator wire. It's working fine 99% of the time but when I throttle back often times get a wildly fluctuating RPM readout for a couple of seconds. Then it will settle back down to what appears to be a correct RPM reading.

This seems to only occur at higher RPMs and when reducing throttle (pretty sure).

I dont have any resistor on the tach pickup wire.

Any ideas as to what to check ?

Thanks in advance,
John Davis

 

[JR]

I too have this problem, fitting resistors certainly helped but it still occurs, seems to me hot weather makes it worse??
JR