User Manual

Operating Information
6
EGT's
engines tend to operate smoother at 25F on the rich side of peak EGT. Fuel-injected engines will provide a
more precise peak. Most engines normally operate within an EGT range of 1300F to 1600F at cruise
power.
Some engine manufacturers allow leaning to peak EGT at 75% power and below on their direct drive nor-
mally aspirated engines. For your engine, check the engine manufacturers recommended procedures. It
is not recommended to lean to peak EGT above 75% power settings. The richer mixture is needed to cool
the combustion temperatures and keep the anti-knock capability of the fuel high enough to prevent detonation
from occurring at the higher power settings.
2. EGT Diagnostics:
Since the EGT is directly related to the combustion temperature, it is an indication of the engines ability to
produce power. If the engine is not producing the correct amount of power, the EGT instrument can be a
very valuable troubleshooting tool as well an early warning system before engine failure occurs. With 1F
resolution, our digital EGT instruments will react to the slightest changes in the combustion process. To
detect a problem, become familiar with your engines normal EGT readings during run-up, climb, cruise and
descent. Any difference from the norm can be a sign of trouble.
During normal operation the EGT will stabilize to 1F for a given throttle and mixture setting. If it does not
stabilize, this can also be the first sign of trouble. With rate and trend information being displayed instanta-
neously and with temperatures being read to 1F, few problems can escape the pilot flying one of Electronics
Internationals analyzer systems. The following is a list of EGT/CHT symptoms and possible problems:
Symptom
Possible Problem
One EGT reads abnormally high. The correspond-
ing CHT reads lower than normal.
Burned valve or broken ring, defective plug, plug
wire or mag.
One EGT reads abnormally high. The correspond-
ing CHT reads higher than normal.
Plugged injector, intake leak.
One EGT reads abnormally low.
Over-sized injector, restricted exhaust, broken or
leaky exhaust header.
High CHTs and/or high EGTs on all cylinders.
Excessive leaning with power settings over 75%.
Detonation due to bad fuel. Closed or restricted
cowl flaps. Missing or loose baffling.
Timing problem or defective mag.
Jumpy readings on one channel.
High EGTs and/or low CHTs on all channels.
This is not an engine problem. Check all connec-
tions and the probe for proper operation. See
Troubleshooting Section of this manual.