Acenels
Active Member
I’m experiencing what I would call interesting RPM behavior on warmup, and I’m kind of curious if anyone else has seen this or similar. After about 3 minutes from engine start and holding at 1000 rpm, if I pull the throttle to idle it starts off settling at its normal (slightly high) 900 RPM, then slowly fades to about 550 rpm, idles a touch rough there for about 30 seconds, then climbs back up to about 900 and stays there (all while on the idle stop).
O-360, about 700 hours snew. Dual PMAGS. I’ve tried leaning out (little increase, about 50 rpm), flipping of the alternator, verified both mags are working independently (and that they are running on ship power at that RPM), and added the electric fuel pump. This has been 40-50 degree weather.
No other issues beyond this. And it runs like a champ after warmup. I’m just scratching my head on it. My fuel PSI has been reading at 8 during warmup, and gets flutter when the engine is running in the lower RPMs, but not sure if that is just from the added vibration. It tends to sit at about 5 in flight, and it is the original mechanical gauge, so I do suspect it is potentially due for a replacement. (Plane used to fly around at about 3, so I suspect it is reading a touch high...but tbd)
I haven’t seen much about mechanical gauges having issues, but it is about 15 years old.
Is all this somewhat normal engine behavior?
Thoughts? I don’t have any immediate concerns on the engine, but the curiosity bug has me on it for sure. And I’m not very smart on engines to begin with, so I have no baseline if this is a normal thing.
O-360, about 700 hours snew. Dual PMAGS. I’ve tried leaning out (little increase, about 50 rpm), flipping of the alternator, verified both mags are working independently (and that they are running on ship power at that RPM), and added the electric fuel pump. This has been 40-50 degree weather.
No other issues beyond this. And it runs like a champ after warmup. I’m just scratching my head on it. My fuel PSI has been reading at 8 during warmup, and gets flutter when the engine is running in the lower RPMs, but not sure if that is just from the added vibration. It tends to sit at about 5 in flight, and it is the original mechanical gauge, so I do suspect it is potentially due for a replacement. (Plane used to fly around at about 3, so I suspect it is reading a touch high...but tbd)
I haven’t seen much about mechanical gauges having issues, but it is about 15 years old.
Is all this somewhat normal engine behavior?
Thoughts? I don’t have any immediate concerns on the engine, but the curiosity bug has me on it for sure. And I’m not very smart on engines to begin with, so I have no baseline if this is a normal thing.