- Cylinder misfire
- Low temperature from the cylinder exhaust ports
- Faulty thermocouple
- Ignition problem
- Low cylinder compression
Operation with a low load can result in low exhaust temperatures. Operate the engine at low idle or near low idle in order to identify a misfire problem.
Troubleshoot the cause of the misfire. Refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable".
Low Temperature from the Cylinder Exhaust Ports
Observe the temperatures for the exhaust ports of the cylinders in the suspect bank.
If any of the temperatures for the exhaust ports are significantly different, determine the reason for the difference in the exhaust port temperatures. Make repairs, as needed.
Observe the temperatures from the thermocouples after the engine is shut off.
When the engine is operating properly, the temperatures from similar locations are reduced at a similar rate. Also, the temperatures from similar locations are comparable.
If any discrepancies are found, switch the suspect thermocouple for another thermocouple. If the temperature problem follows the thermocouple, replace the thermocouple.
If the temperature problem stays at the original location of the suspect thermocouple, investigate the cause for the low temperature.
Use Caterpillar Electronic Technician (ET) to check for diagnostic codes that relate to the ignition system. Troubleshoot any codes that are active or logged.
Inspect the components of the ignition system for the suspect cylinder bank. Refer to Troubleshooting, "Ignition Transformers Secondary Circuit and Spark Plugs".
Perform any necessary repairs.
Check the Cylinder Compression
Measure the cylinder pressures of the suspect bank in order to check for problems that are related to compression.
If low compression is found, investigate the cause of the low compression. Perform any necessary repairs.