To determine if a faulty exhaust system is causing lack of power, perform the following steps:
1. Monitor the exhaust pressure using DDDL 7.0. Connect the scan tool and check the
pressure on the DPF sensor.
2. Start and run the engine at idle with a no-load for approximately 5 minutes, allowing the
engine coolant to reach normal operating range.
3. Install the vehicle on a chassis dynamometer and run the engine speed to full load.
[a] If the exhaust back pressure at full load is less than 10.1 kPa (3.0 in.Hg), check for
high inlet air temperature; refer to section 12.9.
[b] If the exhaust back pressure at full load is 10.1 kPa (3.0 in.Hg) or greater,
refer to section 12.8.1.
Engine Exhaust System Resolution
Perform the following steps to resolve the engine exhaust system:
1. Visually inspect the engine exhaust system; refer to OEM guidelines.
2. Remove the Aftertreatment Device (ATD), refer to the Aftertreatment System Technician’s
3. Install the aftertreatment test pipes (J-48388-1) for 5 inch exhaust, or aftertreatment test
pipes (J-48388-2) for 4 inch exhaust. Deactivate the pressure and temperature sensors using DDDL 7.0.
4. Verify exhaust system resolution; refer to section 188.8.131.52.
Test the Engine with Replaced Exhaust System
Perform the following steps to determine if replaced engine exhaust system components resolved
lack of power condition:
1. Start and run the engine.
2. Test drive the vehicle to ensure lack of power has been resolved.
[a] If the lack of power has been resolved refer Aftertreatment System Technician’s Guide
(7SE63) for aftertreatment diagnostics.
[b] If lack of power occurred during the test drive, shut down the engine. Reinstall the
aftertreatmnet. Check for high inlet air temperature; refer to section 12.9.