engine stumble at WOT
in 912 / 914 Technical Questions
7 years ago
I have a engine stumble that I intermittently experience at WOT both on the ground and in the air.
The engine is a 912ULS in an RV12, I'm in phase I on this plane, meaning everything is brand new and I'm flight testing, I saw this issue in the first flight and every flight since bar one.
I have taken the carbs off, taken the top off them and cleaned every orifice with both carb cleaner and then compressed air. I have completely redone the carb and sync setup every single step, the carbs show good balance from idle through WOT.
One other strange issue is that when I start my rollout my RPM is 5170 and by the time I complete my climbout it is at 5050 (yes it is decreasing even though the prop should be unloading as airspeed increases), I promise my throttle setting is hard against the firewall no change. Here is that in savvy
when the stumble occurs I'm getting a spread in my EGT of about 150F higher on the left and I have confirmed that is indicating the correct sensor and side
I have captured the stumble on the ground in a video, I swap between instruments and my carb sync tool is still attached, doesn't seem to go out of sync, the EGTs separate and RPM wanders
you tube video
I did talk to Roger Lee about this, he had suggested cleaning out the carbs, which I did and re-do on the mechanical and pneumatic sync.
The engine is a 912ULS in an RV12, I'm in phase I on this plane, meaning everything is brand new and I'm flight testing, I saw this issue in the first flight and every flight since bar one.
I have taken the carbs off, taken the top off them and cleaned every orifice with both carb cleaner and then compressed air. I have completely redone the carb and sync setup every single step, the carbs show good balance from idle through WOT.
One other strange issue is that when I start my rollout my RPM is 5170 and by the time I complete my climbout it is at 5050 (yes it is decreasing even though the prop should be unloading as airspeed increases), I promise my throttle setting is hard against the firewall no change. Here is that in savvy
when the stumble occurs I'm getting a spread in my EGT of about 150F higher on the left and I have confirmed that is indicating the correct sensor and side
I have captured the stumble on the ground in a video, I swap between instruments and my carb sync tool is still attached, doesn't seem to go out of sync, the EGTs separate and RPM wanders
you tube video
I did talk to Roger Lee about this, he had suggested cleaning out the carbs, which I did and re-do on the mechanical and pneumatic sync.
