2005-Ford-E350/RPMLimitPowerIssue/progress.md

RPMLimitPowerIssue - Progress Tracker

Current Status

✅ DIAGNOSIS COMPLETE - Clogged catalytic converters confirmed

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Catalytic Converter Removal Instructions

Tools Needed

• Floor jack and jack stands (or drive-on ramps)
• Penetrating oil (PB Blaster, Liquid Wrench, or similar)
• 10mm socket/ratchet (for O2 sensor connectors)
• O2 sensor socket (22mm or 7/8" typically)
• 15mm or 17mm wrench/socket (for converter mounting bolts)
• Air impact wrench (helpful but not required)
• Pry bar
• Safety glasses
• Gloves
• Wire brush
• Anti-seize compound (for reassembly)

Safety First

• Allow exhaust system to cool completely - Hot exhaust can cause severe burns
• Securely jack up the van - Use jack stands, never rely solely on a floor jack
• Work in a well-ventilated area - Exhaust fumes are dangerous

Removal Steps

1. Position the van

• Drive onto ramps OR jack up the front and place on jack stands
• Ensure the van is stable and secure

2. Apply penetrating oil

• Spray penetrating oil on all exhaust mounting bolts
• Wait 15-30 minutes for the oil to penetrate
• Reapply if bolts are very rusted

3. Disconnect O2 sensors

• Locate the forward O2 sensors (before the catalytic converters)
• Disconnect the electrical connectors (10mm socket)
• Use O2 sensor socket to remove the sensors from the exhaust pipes
• Set sensors aside - you'll reinstall them after the new cats are installed

4. Remove the catalytic converters

• The 2005 Ford E350 5.4L has TWO catalytic converters (one on each bank of cylinders)
• Find the mounting bolts that connect each converter to the exhaust manifold
• Remove the bolts (15mm or 17mm typically)
• Use a pry bar to gently separate the converter from the manifold
• Remove the converter

5. Repeat for the second converter

• There are two converters - one on each side of the V8 engine
• Repeat steps 3-4 for the second converter

6. Clean up

• Clean the exhaust manifold mating surfaces
• Inspect the O2 sensors - replace if damaged or very old

Temporary Setup (if needed)

• If you removed the O2 sensors and want to run temporarily, you can leave them out
• However, this will trigger check engine lights
• Use O2 sensor simulators/spoofers if you want to avoid CEL

Reinstallation

1. Apply anti-seize to the exhaust manifold threads
2. Install new catalytic converters
3. Torque bolts to specification (typically 25-35 ft-lbs for exhaust manifolds)
4. Reinstall O2 sensors (do not overtighten - hand tight plus quarter turn)
5. Reconnect O2 sensor electrical connectors
6. Lower the van
7. Start engine and check for exhaust leaks
8. Clear any diagnostic codes

Estimated Time

• Experienced mechanic: 1-2 hours
• DIY first-timer: 2-4 hours

Notes

• If bolts are severely rusted, you may need to cut them off
• Consider heat shields - they can be removed for easier access
• Some converters are bolted to the exhaust pipe rather than the manifold - check your specific configuration
• The 2005 E350 may have underbody converters in addition to manifold converters
• Verify your exact configuration by looking at the exhaust system before starting

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Completed

• Initial project setup
• Created project documentation structure
• Documented symptoms and known work
• Identified 7 potential causes
• Confirmed diagnosis: Removed forward O2 sensors → full power returned immediately

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Next Steps

1. Remove both catalytic converters - See instructions below
2. Order replacement catalytic converters (primary fix)
3. Reinstall new cats and O2 sensors
4. Test drive to verify full power restored
5. Consider O2 sensor replacements if old/damaged

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Diagnosis Details

Test performed: Removed forward O2 sensors (located upstream of catalytic converters) Result: Power immediately returned, RPMs no longer limited at 3000 Conclusion: The catalytic converters are severely restricted/clogged. When the O2 sensors were removed, they created enough clearance for exhaust to flow freely, bypassing the restriction.

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Notes

• TPS already replaced with no improvement
• Spark plugs already replaced with no improvement
• This was NOT a fuel, air, or ignition issue - purely exhaust restriction
• The forward O2 sensors are embedded in the exhaust stream and were blocking the flow when clogged cats were present

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Last Updated: 2026-03-29 18:48 EDT