Taildrgr
Well Known Member
I have searched and found threads dealing with rpm surging at full power settings, but my surging issue is at idle speeds.
I have a new Lyc IO-360-M1B, Hartzell CS C2YR-1BFP/F74972 prop, and MT P-860-4 Rev G governor from Van's, all with 32 hours time.
I set my prop pitch screw for max static rpm of 2690 rpm. I have not touched the governor.
The rpm is rock solid while flying.
At about 5 hours into phase I testing, my idle/taxi rpm started surging about 200 rpm after I stopped at the fuel pump after a flight. When I restarted up and taxied to my hangar, the engine was surging. I thought it was vapor lock (I only use 100LL). 90 degr day in Texas.
Days later, on the next flight, the engine was still surging on initial startup (cold) and did not stop when the engine warmed up or taxiing to the runup area. The prop cycled normally at 1700 rpm, so I took off and stayed over the airport, landed, and the surging was gone. It did not surge again for 27 hours so I thought it was just an initial break in issue.
Yesterday, at 32 hours total time, after a 2 hour flight, I landed, got fuel, and again, on startup it was surging. It was a cool day at 54 degr OAT but the engine was hot. Still 100LL. I have not restarted the engine since yesterday so I don't know if it will continue to surge when cold.
On the ground, changing rpm from 650 to 1200, changing the mixture from full rich to lean, and turning on the boost pump, all have no effect. I have not tried to move the prop control because I thought the governor has no effect at idle speeds. I also checked my prop governor control linkage and it is solid. The lever is on the stop screw with the prop control out 1/8 inch from the panel.
So, why would a fuel injected engine surge at idle? Hot or cold. Is it the prop or a fuel flow issue?
Any suggestions on what to investigate would be appreciated.
I have a new Lyc IO-360-M1B, Hartzell CS C2YR-1BFP/F74972 prop, and MT P-860-4 Rev G governor from Van's, all with 32 hours time.
I set my prop pitch screw for max static rpm of 2690 rpm. I have not touched the governor.
The rpm is rock solid while flying.
At about 5 hours into phase I testing, my idle/taxi rpm started surging about 200 rpm after I stopped at the fuel pump after a flight. When I restarted up and taxied to my hangar, the engine was surging. I thought it was vapor lock (I only use 100LL). 90 degr day in Texas.
Days later, on the next flight, the engine was still surging on initial startup (cold) and did not stop when the engine warmed up or taxiing to the runup area. The prop cycled normally at 1700 rpm, so I took off and stayed over the airport, landed, and the surging was gone. It did not surge again for 27 hours so I thought it was just an initial break in issue.
Yesterday, at 32 hours total time, after a 2 hour flight, I landed, got fuel, and again, on startup it was surging. It was a cool day at 54 degr OAT but the engine was hot. Still 100LL. I have not restarted the engine since yesterday so I don't know if it will continue to surge when cold.
On the ground, changing rpm from 650 to 1200, changing the mixture from full rich to lean, and turning on the boost pump, all have no effect. I have not tried to move the prop control because I thought the governor has no effect at idle speeds. I also checked my prop governor control linkage and it is solid. The lever is on the stop screw with the prop control out 1/8 inch from the panel.
So, why would a fuel injected engine surge at idle? Hot or cold. Is it the prop or a fuel flow issue?
Any suggestions on what to investigate would be appreciated.
