Demonstration of leaning at low power showing C1 and C3 are running rich
October 13, 2026 · KORS ramp, before KORS → KBLI · Recording 776
C1 and C3 EGT keeps rising as C2, C4 and C6 EGT falls during leaning. The recorded response supports C1/C3 remaining rich of peak relative to those cylinders. C5 also continues rising during the clearest interval.
Six cylinders · one leaning sweep
23:45:22 UTCLoading engine cutaway…
Drag to rotate · motion slowed for visibilityEGT, fuel flow and the small EGT traces are recorded data. ROP/LOP states are inferred from the early EGT turnovers; C1/C3/C5 have no measured peak in this leg. The engine is an illustrative cutaway; motion, glow and fuel spray do not measure combustion temperature or individual-cylinder fuel delivery.
The opposing response, measured
See the complete test traces ↓23:45:02–23:45:35 UTC (16:45:02–16:45:35 PDT). Fuel flow 7.73 → 7.06 GPH; MAP 21.09 → 21.57 inHg; RPM 1665 → 1620. Groundspeed stayed at zero.
| Cylinder | Start | End | Change | EGT response |
|---|---|---|---|---|
| C1 | 1356°F | 1406°F | +50°F | Rising |
| C2 | 1455°F | 1429°F | -26°F | Falling |
| C3 | 1319°F | 1352°F | +33°F | Rising |
| C4 | 1413°F | 1400°F | -14°F | Falling |
| C5 | 1421°F | 1454°F | +32°F | Rising |
| C6 | 1419°F | 1386°F | -33°F | Falling |
What the trace establishes
C4 and C6 turn downward near 23:44:53; C2 near 23:45:01. C1/C3 keep rising through 23:45:35. That separation supports relative richness. The recording does not show all four other cylinders falling together: C5 rises too.
The table uses five-second endpoint medians to reduce sample noise. Three- and seven-second medians preserve every cylinder’s direction. Comparison CSV.
Complete test traces
23:44:30–23:46:50 UTC · 141 native samplesShading marks the 33-second comparison. Click a point in the leaning leg to move the 3D replay to that sample. The dashed cursor follows the replay. Fuel flow reverses near 23:46; the later fluctuations are retained for review.
Interpretation and limits
This demonstrates a cylinder-to-cylinder mixture-response difference, with C1/C3 on the richer side of the early-peaking cylinders. It does not identify the faulty component. RPM falls and MAP rises during the sweep; oil temperature rises from 91°F to 101°F during the comparison. All six CHTs rise as the engine warms. Probe response and changing conditions prevent a calibrated six-cylinder peak spread or individual mixture-ratio measurement.
The 3D replay stops at 23:45:35, before the larger RPM/MAP shifts and fuel-flow reversal. No measured peak is assigned to C1, C3 or C5 in that leg. Review the flow-divider research alongside the low-power investigation for candidate causes.
Source and validation
Native file: log_261013_234201_KORS.csv.
The extracted samples exactly match the lifetime cache. No time gaps, interpolation or smoothing are used in the displayed traces.
Position is approximately 48.7042°N, 122.9100°W at KORS; the pilot identifies the event as gradual mixture leaning on the ramp.
Analysis, controls and sensitivity results · JSON.
Engine anatomy reference: Lycoming AJ1A illustrated parts catalog, cylinder, piston and fuel-nozzle assemblies. Geometry is illustrative.
SHA-256: de4154e2b743a4b2809d5b17d35cb44faac66e54bdba2a1e66fa96dbb040cfb6. The source flight and the return flight are included in the full archive, trend explorer and geographic view.