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Well, after another flight on the weekend looks like I may be getting oil cooling to a point good enough for sustained flight. but found out engine tuning can invoke a kaleidoscope of emotions.
Tracy's .1 uF cap fix on the A MAP sensor fixed RFI on the ground, engine seemed smooth & strong so took another flight. with a really long taxi to the threshold oil temp climbed to 200, while I was rolling noticed it dropping so more power & take off. My exhaust is high on the forward cowl so easily visible during flight, I could see it moving at about 1-2 pulses/sec (no other cues & probably not noticeable if exhaust not visible), but assumed engine is missing so decided on a low level circuit to land. radioed intentions & engine stutters! no more RT. This had me stuffed so decided to sleep on it for a couple of days to try and work out why this engine is so scared of flying, and actually knows when its left the ground. Here's what I reckon, its a combination of an engine that runs so smooth even when extremely out of tune, that it gives a false sense to the operator that they know what they are doing, 60lb injectors & a variable pitch prop. I think the engine was just about flooding in flight, a little bit of RFI, injectors open for just a little bit longer and it goes over the edge, no proof but will try running really rich and keying the radio tomorrow before I try to tune the engine. Most of my previous tuning was with the prop at the lower half of its pitch range as the prop manual advised against operating the prop on the ground at coarse pitch. I think this is a big mistake as it don't fly on fine pitch. So I'm going to start from scratch and do it all again much coarser. To get some reference I decided to try and decode the engine info page on the EM2. Geez that Hex to Decimal conversion is complex. anyway If I've interpreted it right I'm stunned to find some settings way off what they should be. from EC2.A8 manual.
parameter, (row-column),hex,dec
Staging point,(4-3),15,21" SECDIF,(3-5),34,52 R1DIF,(3-3),80,128 R1DIFA,(4-6),80,128 Ignadv,(4-4),00,0 Inj Flow,(3-7),6E,110 I had adjusted Inj flow with mode 3 and really thought I'd cleared mode 6 when I installed the injectors. the others I really don't know how they ended up different from defaults. I did suspect the R1dif as both rotors have 2 egt's, 1 for EM2 & 1 for efis, strange thing is, EM2 shows R2 as way hotter than R1, efis is reverse. but anyway, as manual states to leave mode 4 alone until motor is running perfectly in every other respect, I hadn't touched it.
Tracy, when you got time, I'd really like to know what all the other numbers relate to on the engine info screen to see if any others are in error. Andrew |
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