A little history. Engine has about 450 hours, always ran quite well,
replaced upper ignition module about two years ago.
On recent full boost takeoff, got to about 900 feet leveled off, pulled
throttle back and engine ran severe rough, pulled back to idle and engine
ran ok, didn't stop! Landed. Checked fuel filter, ok, looked for anything
around carbs, nothing. Tried several full run ups, ok. Tried second take off
everything fine, pulled back and again engine ran severe rough, pulled back
to idle, ran rough, landed. Parked plane, got tools, next day removed carbs
looked for issues. Found one of the four screws that holds down the rubber
diaphragm loose, very strange because I have never removed this before.
Anyway figured this was my problem. Fixed took off all ok. Got home. Next
day tried full boost, same issue again, didn't take off. Got carburetor
repair kit and went through both carbs. Reinstalled carbs double checked.
Started right up, as I move the throttle past 2300 rpm the yellow caution
light starts blinking, engine runs rough, reduce rpm the light goes off,
increase the light comes back on. Seems the engine runs off the idle jet ok
but not on the main jet.
I have also checked the waste gate for proper function, fuel pressure ok,
turbo lights come on and go off as they should when master is tuned on, I
have looked at the vent lines. The yellow blinking light can indicate a
sensor failure, seems like it would continue blinking if there was a
failure. Seems odd that it stops at low rpm. Seems I have some kind of a
vacuum or pressure issue, but am running out of ideas. I am about to go and
recheck again! Could a faulty sensor cause this?
Hope someone out there has some wise thoughts on this frustrating problem.
Worse yet, we have beautiful spring flying weather!
Thanks for help.
Jerry
914 Mono XS
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