IOF-360 Engine Rough Running
I have a problem with a rough running engine that is having everyone here tearing their hair out with frustration.
I have an RV7 fitted with an IOF-360 A1B6 200p Angle Valve engine (Aerosance FADEC controlled), The engine was built around 4 years ago and we are in the initial test flying phase, and have flow around 3 hours so far.
The symptoms are:
? Cruising at 25 square ? smooth as silk and pulling like a train.
? Prop at 2500 rpm, pull back manifold pressure, continually smooth until manifold pressure drops below around 19-20 inches and then engine starts running rough and cylinder 2 and 3 EGTs drop to nothing. Cylinders 1 and 4 appear to be running perfectly.
? Continue to pull back the manifold pressure and engine starts running very smoothly again below around 14 inches.
? Increase throttle and again above approx 19 inches engine runs very very smoothly.
After consulting several licensed engineers in this country we checked the compressions and dry valve clearances; all of which were spot on. We pulled the rockers off cylinders 3 and 4 and ?tapped? the exhaust valve stems to try and clear the valve seats to see if that would make any difference. The symptoms stayed the same.
I am putting feelers out everywhere (including Lycoming who now own the FADEC system), but wondered if anyone on this wonderful forum had any ideas.
Thanks in desperation!
Mark
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