Pinpoint Test A: Loss Of Power

Exhaust System


Pinpoint Tests


Pinpoint Test A: Loss of Power

Normal Operation

The diesel exhaust system provides an exit for exhaust gases and reduces engine noise by passing exhaust gases through the catalytic converters and a muffler assembly.

NOTE: The vehicle can have a lack/loss of power, odor, a noise or a "no start" concern. These concerns may be related to the exhaust system. Carry out the following test, if no trouble codes were stored. This test is for diagnosing the source for these conditions.

This pinpoint test is intended to diagnose the following:
- Restricted or damaged pipes
- Muffler
- Catalytic converter



PINPOINT TEST A: LOSS OF POWER

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A1 EXHAUST SYSTEM INSPECTION


- Inspect the exhaust system for damage or deterioration. Look for cracks, punctures, leaks, loose connections, dents or unusual bending.
- Is the exhaust system OK?

Yes
GO to A2.

No
REPAIR or INSTALL new any damaged or deteriorated exhaust components. TEST the system for normal operation.

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A2 EXHAUST SYSTEM FROZEN


- Inspect the exhaust system for frozen condensation.
- Park the vehicle inside to thaw.
- Is the restriction gone?

Yes
Exhaust system is OK.

No
GO to A3.

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A3 BACK PRESSURE TEST


- Position the vehicle on a hoist. Refer to Maintenance/Service and Repair.
- Remove the muffler and tail pipe assembly. Refer to Muffler and Tailpipe - 6.0L Diesel Muffler and Tailpipe.
- Start the engine and gradually increase the engine speed to 2,000 rpm with the transmission in NEUTRAL.
- Is the restriction gone?

Yes
INSTALL a new muffler and tail pipe assembly.

No
GO to A4.

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A4 BACK PRESSURE TEST


- Remove the catalytic converter assembly. Refer to Catalytic Converter - 6.0L Diesel Service and Repair.
- Start the engine and gradually increase the engine speed to 2,000 rpm with the transmission in NEUTRAL.
- Is the restriction gone?

Yes
INSTALL a new catalytic converter assembly.

No
No indications of a restriction have been detected. CONDUCT a diagnosis on other suspect systems. CLEAR the DTCs.

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