docs: Add catalytic converter removal instructions

Added comprehensive step-by-step instructions for removing both catalytic converters:
- Tool list with specific sizes
- Safety precautions
- Detailed removal steps
- Reinstallation guidance
- Estimated time (1-4 hours depending on experience)

RPMLimitPowerIssue/progress.md

@@ -5,6 +5,86 @@
 
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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
+
+---
+
 ## Completed
 - [x] Initial project setup
 - [x] Created project documentation structure
@@ -15,10 +95,11 @@
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 ## Next Steps
-1. [ ] **Order replacement catalytic converters** (primary fix)
-2. [ ] Reinstall O2 sensors after cat replacement
-3. [ ] Test drive to verify full power restored
-4. [ ] Consider O2 sensor replacements if old/damaged
+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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