914 surging at altitude
in General Tech Discussion
11 years ago
I have a 914 with 90 hours. I have done about 15 since taking ownership. I have done very little flight at altitude due to weather, however recently did a sustained climb at 100% throttle through 7500 when the engine started to surge. Temps and pressures were all good. Boost pressure was constant, only RPM varying at about a cycle per second. The surge disappeared coming back to 80% power. I checked all the filters through to the fuel pumps, and tried again. 3500 feet and the surging came on. Switched the prop to manual to rule it out, noted constant boost pressure so turbo must be innocent, changed pumps, changed tanks. No change. Again disappears with power reduction. Full smooth 115% power available at sea level before landing. Checked turbo hoses, airbox to carby hoses, balance and boost pressure lines visually for leaks or wear points, and put clamps on the carby balance tube (none in place). Climbed to 5500 before surging. I vaguely recall QNH of 1032 for the 7500, 1003 for the 3500 and it was 1013 for the 5500.
Any ideas?
Any ideas?
