Ranger_10X

So I've noticed for about a year this rattling noise when transitioning from idle to just above, and back down - think next to the drive up window at the local grease-burger and moving up to next in line. Just bumping the throttle, rattles as rpm moves up and again when slowing down. Last time I had it on the rack I asked my guy to look into it - I thought it sounded like a CAT shield. He couldn't find it but said it seemed to be coming from the inside of the CAT? Now, for the last six months I've had an issue with missing and exhaust popping (backfire) when under heavy acceleration when cold. Now it seems to happen almost all the time under full throttle. TODAY, It popped the P0420 code - catalytic efficiency lost on bank 1. I've been reading around and most have indicated that the catalytic converter needs replaced - but that something has caused it to fail at just 100k miles. Someone also mentioned that a cold air intake could have contributed. I've been running a cold air intake for 9 years with no problems till now. Truck also has a Corsa performance exhaust. Plugs in this truck have never been changed - nor have any of the coil packs or fuel injectors. Suggestions, thoughts, comments welcome. THANKS....
Additional info, I also seem to have the dreaded exhaust manifold leak on the DRIVER side. I had repaired this on the passenger side a year ago. Someone mentioned that this might be contributing to the problem, but since the code said Bank 1, wouldnt this be the wrong side?

chickenwire

I've had a CAT fail on a car and it rattled loudly at the 1-2 shift (manual trans in that car). The CAT was plugging up and had an internal "ring" that broke loose and would rattle until it heated up.

Most engine control modules will run the engine rich "when in doubt" in order to keep from cooking the engine by running lean. When an engine runs rich it can plug the cat.

I can't say for certain but your CAI may have caused problems over the long haul.

Hopefully other members can chime in.

650NutKase

I had mine go out during a road trip. My truck is 100% stock. The only thing I can attribute to mine is simply a factory defect. I was right around 100k give or take when it happened. The CAI can make you run lean, in which case, egt's are increased. The increase in heat can melt the internals of the cat. Usually, the recommendation is to get the truck tuned, especially after the addition of a CAI.

RLXXI

80k is the warranty on most emission components including the cats, @ 100,000 miles they are simply worn out. Replace them and keep rolling.

P.S. Not sure what year they started but all Ford trucks now come equipped with CAI from the factory.
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