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I've got a '01 F250SD with a 5.4L. Since about Jan. 06 the enging light started to come on some times when I plow snow. The code has something to do with the bank one and bank two are lean. The last time it came on is when I was driving down the road. I have replaced both O2 sensors with ford parts and the also replaced the fuel filter. My mech. said it might not be getting enough air and I should buy a K&N Injection Kit, and also a super chip of some type. If anybody had any info or has heard of this type of thing that would be great. Thanks
Aaron
I personally wouldn't want to chip my vehicle or put an intake on it before it is running in top condition. Last I knew, if the truck was running lean, then it is not getting enough fuel, not enough air, and I don't think that had changed. I would have recommended the fuel filter since that helped my car but seeing you already changed that, I would say check your fuel pressure. Could maybe be your pump going bad.
Check all your intake hoses and especially your PCV hose and elbow at the intake manifold near the TB. They are notorious for breaking or coming loose which will make the vehicle run lean and set off the lean codes. Remember, when the ECU says your vehicle is lean, it is currently adding more to your fuel trim (Because it thinks its lean) so your vehicle will be running rich out the tailpipe.
The TB = Throttle-body, which is in the intake. It would be attached to the upper plenum on one side and the flexible elbow going to the intake tube on the other side.
It's basically step by step pictures of how to replace it if that's the problem. I've worked on several Expedition (5.4-liters) that have the lean code(s) both banks and everytime I always find the PCV elbow at fault. I hope this is your problem too because it's a super easy and very cheap fix as oppose to replacing everything. Although, I'm not sure if the PCV setup is the same on the F250 as it is in the Expedition/F150s. I've never worked on a 5.4 superduty, only V10s and PSDs.
I had one customer with an Expedition come in with the lean codes and he basically replaced all four oxygen sensors, mass air flow sensor, fuel filter, air filter and all at his previous mechanic's "suggestions." Nothing cured it. All it was was a simple PCV hose to fix it.