Fuel/Air Profile - Electronics International UBG-16 Operating Instructions Manual

When viewing "Profile" the bar graph display shows the fuel/air distribution for your engine. This display is
intended as a technical view of how your engine is operating. Once you know the fuel/air distribution for your
engine, its easier to make logical decisions on how to run your engine (rich of peak, at peak, lean of peak, lean on
climb, etc.). Also, it can be a troubleshooting tool for those hard-to-find problems (engine runs rough, not devel-
oping power, burns too much fuel, etc.).
The Profile display is only accurate when viewed after you have leaned all of the cylinders past peak EGT in the
Lean Operating Mode. The lit box around a specific cylinder number (located at the top of the columns) indicates
the cylinder that first reached peak EGT. This is the leanest cylinder and there should only be one bar lit (if there
is more than one bar lit, the Profile display is not accurate and you will need to perform the leaning process
again). The remaining EGT and TIT columns will have one or more bars lit.
When the first (leanest) cylinder reaches peak EGT, a baseline temperature is established for each cylinder. For
every 5'F an EGT must rise in order to reach peak (above the baseline temperature), one bar will be lit. The
column with the most bars lit represents the cylinder that has the highest EGT rise before reaching peak. This is
the richest cylinder. The more bars lit in a column the richer the cylinder.
For Example: Figure 1 shows cylinder #2 reached peak EGT first. Cylinder #1's EGT rose 50'F before it
reached peak (10 bars x 5'F = 50'F). Cylinder #1 is richer than cylinder #2.
Cylinder #4 only rose 15'F before it reached peak EGT (3 bars x 5'F = 15'F). Cylinders #2, and #4 reached peak
EGT almost at the same time. Notice the right bank of cylinders (1, 3 and 5) on this engine is running much
richer than the left bank (2, 4 and 6). This is a typical Profile display for a carbureted engine or an IO-470 or IO-
520.
Figure 2 shows a typical fuel/air distribution profile for a well-balanced engine. All the cylinders reached peak
EGT nearly at the same time. A well-balanced engine runs smoother, develops more power and burns less fuel
when leaned out in cruise.
Carbureted Engine
or IO-470 or IO-520.

Fuel/Air Profile

Fuel/Air Profile Fuel/Air Profile
Fuel/Air Profile Fuel/Air Profile
Figure 1 Figure 1 Figure 1 Figure 1 Figure 1
Well Balanced Engine
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Figure 1 Figure 1 Figure 1 Figure 1 Figure 1