2003 Ford Expedition 5.4L Emissions Problems: Misfires, Stalling, and EVAP Leak
My 2003 Ford Expedition 5.4L engine is experiencing persistent emissions-related issues. After replacing the fuel pump, fuel filter, and upstream O2 sensors, the truck still stalls when hot, idles roughly under load, and exhibits delayed response during warm-up. When left idle for about 30 minutes, it runs smoothly for a short period before symptoms return. Current diagnostic codes include: EVAP system leak detected, all-cylinder misfire, catalyst efficiency below threshold, and ignition distributor (crankshaft position sensor) fault. We initially replaced the fuel pump and filter, followed by the complete CADS (Crank Angle Detection System) module. The problem persists. After installing new upstream O2 sensors, the EVAP code did not clear, but new misfire and catalyst efficiency codes appeared on Bank 2. I am now planning to replace the crankshaft position sensor. I suspect that the root cause may be damaging my CADS system. Are there any other diagnostics or components I should investigate? Is the EVAP leak a separate issue? Any suggestions for troubleshooting steps or additional checks would be greatly appreciated.
The mention of 'CADS (the whole kit)' might actually refer to the catalytic converter — could that be what you're describing? For better troubleshooting, please list all current diagnostic codes in your first post. Avoid replacing parts without a clear diagnosis. Recommended test: Check fuel pressure under normal conditions, then perform a KOEO (Key Off, Engine Off) observation of fuel pressure drop to identify potential fuel delivery issues.