Idle flutter
 

I noticed that my oil pressure flutters between 25-30 when the engine is idling. The tach is almost perfectly steady, but I can hear a tiny change in the pitch of the motor that seems to sync with the fluttering gauge. Any idea what causes this? I'm thinking that the ECU is adjusting fueling to maintain idle, but it seems a bit sloppy.

it's just the idle control valve..which is controlled by the ECU..from all the sensors that are feeding it info...DME temp II, ox sensor, intake manifiold flap postion

some idle control valves are lazy and are more irritating than anything...

the engine rpm which is controlled by the idle control valve will cause the oil prssure indicator to fluctuate up and down with the rpm of the engine...normal