P0420 with surging often indicates exhaust leak affecting O2 readings. You replaced one manifold gasket - check the other side. V10s commonly have issues with both manifolds.
Essential guide for Ford E-Series Class C motorhome chassis covering suspension, maintenance, and common issues.
The Onan 5500 can be tuned up with quality aftermarket parts when OEM parts are unavailable. Use NGK 3432 spark plugs, Wix 57358 oil filter (not 57398), and zinc-containing oils like Rotella T6 for optimal performance.
V10 surging with air/fuel codes often has cheap fix - vacuum leak, intake gasket, or exhaust leak. Do smoke test or spray test before replacing more expensive parts.
Yes, you're absolutely on the right track - your testing clearly points to a PCM failure in the ground switching circuit for the drivers side coil bank. The fact that you have +12v but no ground pulse during cranking confirms the PCM isn't completing the circuit.
A check engine light on your 2022 Ford E450 after recent service likely indicates an emissions system issue. Get an OBD2 scanner to read the exact code first, then check for loose connections, damaged vacuum lines, or a loose gas cap before returning to the dealer.
The Walker 21470 big truck muffler can provide modest performance gains and deeper sound on a 2003 Ford F53 chassis. Installation is straightforward but requires proper exhaust system modifications and professional welding for best results.
Cummins in RVs are diesel engines or Onan generators. Gas chassis use Ford or GM. Cummins diesel and Onan generators need regular maintenance.
Multiple engine failures on a 2016 Winnebago Vista suggest deeper issues that need investigation. Consider independent diesel shops, remanufactured engines, and thorough diagnosis before committing to a third expensive replacement.
Your story is a perfect cautionary tale about how ignoring gradual performance decline can lead to catastrophic engine failure. The combination of blocked exhaust flow and oil starvation from running 500 miles with severe backpressure absolutely justified your decision to replace rather than rebuild the engine.
For your 2000 E450 V10's uphill struggles in the Rockies while towing, rear end gear change will provide the most significant improvement. An SCT programmer offers moderate gains, while K&N filters and cat removal provide minimal power increases.
Lean on both banks indicates system issue not O2 sensor failure. Check for vacuum leaks, MAF sensor, and fuel pressure. Minor transmission leak in reverse is likely front pump seal weeping - monitor but not critical unless worsens.
2021 F53 uses 7.3L V8 with factory exhaust. Aftermarket options limited. Custom work possible but minimal power gains expected.