Navistar MaxxForce DT Diagnostic Manual page 40

DIAGNOSTIC MANUAL
Step
7 Diesel Particulate Filter ( DPF) Snap Acceleration Test (Quick Test).
This procedure checks the DPF for cracks or internal damage
without removing the DPF from the vehicle and is used to test basic
functionality of the diesel particulate filter. This is to be done prior to
removing the DPF.
1. The transmission must be in neutral and the parking
brake applied.
2. Start and idle the engine.
3. Rapidly snap the accelerator pedal from idle to full
throttle. This can be performed multiple times.
4. During the engine accelerations, visually check for a
heavy black smoke exiting the exhaust pipe.
Is black smoke visible?
Step
8 Determine if Diesel Particulate Filter (DPF), Pre-Diesel Oxidation
Catalyst (PDOC), and Diesel Oxidation Catalyst (DOC) are
contaminated. Remove the DPF, PDOC, and DOC (see Exhaust
System Service Manual), and check for signs of lube oil and coolant
contamination.
NOTE – A black staining in the exhaust tailpipe can occur on
applications that experience high idle times. This is normal and
the DPF should NOT be replaced.
Are the DPF, PDOC, or DOC contaminated?
Step
9 Determine if DPF, DOC, and PDOC are reusable see DPF and DOC
reuse guidelines page 159.
Based on DPF and DOC Re-Use Guidelines, are the DPF, DOC,
and PDOC reusable?
36
Action
Action
Action
https://www.truck-manuals.net/
Decision
Yes: Go to Symptom 5
(Medium Duty): Black smoke
page 44.
No: Go to step 12
Decision
Yes: Go to step 9
No: Go to step 10
Decision
Yes: Go to step 11
No: Replace failed
component(s). After repairs
are complete, go to step 11.