2005 Expedition 5.4 3V cat knock
 

Hello from Oregon! New member here, but definitely not new to Ford! Been wrenching on Explorers and expeditions and f150s for years and do all my own work.

Been chasing down a weird issue on a new to me 2005 EXP EB with the 5.4 3v. with about 135k on it. I bought it from a dude for 6 grand and the car is pristine but had some weird sounds in the motor. Long story short i tracked one of the knock sounds down to the #2 plug on the passenger side being loose (common problem I am aware of). Tightened that up before it popped out and that went away...sweet!!! (also checked all other 7 plugs to be sure they were tight) The other noise I'm still hearing sounds like rod knock or lower engine bearings going bad near the oil pan. Got my trusty rubber hose out and started stethoscoping out under the car and low and behold this loud metallic knocking sound is coming from the passenger side CAT back next to the oil pan/tranny! i place the hose on it and its deafening. placing my hose on the transmission housing and oil pan there is no knocking sound present. The noise only starts to happen once the car is warmed up and in park or drive at idle. Once I'm up to speed its not really audible. Heres the million dollar question for the brain trust...ECU is not throwing any codes at all...but the car does run rich and I'm thinking ive got the known injector problem on this motor as well which i need to fix. Could the excess fuel be killing the cat w/out it throwing codes on the ECU for o2? Truck runs decently around town and seems to have plenty of power. I have a 1997 F150 with almost 310k on it (original motor, trans, cats, etc) and it purrs like a kitten and have had no issues with cats, or injectors, or anything. To me it sounds like theres something rattling around inside the middle of the cat...like the innards are coming apart or something metal got by it...

If i end up having to replace the cat, is there any known good recommendations for replacements? I've seen some pre-built cats with pipes that are direct bolt in for 2-300 bucks off ebay, etc but have no idea on quality.

I think you have it pinned exactly. Rich running will kill cats.

Replace both cats and all the injectors.

http://www.rockauto.com/en/catalog/f...converter,5808

I would go with the Walker. Additional parts needed:

http://www.rockauto.com/en/parts/wal...337,clamp,5816

I would go with the new Motorcraft injectors.

http://www.rockauto.com/en/catalog/f...+injector,6224

Thanks!! I appreciate the advice. I was absolutely terrified that it was something in the bottom end of the motor. do you think it would be absolutely necessary to replace both cats since the knocking is only coming from the passenger side? Or would it be ok to just let things sit until the other one starts knocking? If I can save some money on this truck I'd absolutely like to. Also do you feel it wise to replace the plugs while Im at it? guy said they were done around 30k ago and with all that extra fuel im wondering if they could be fouled already. Also, should i replace the O2 sensors while I'm at it? or let those fail and replace when needed. I've never had to do any of this on my other fords which makes me question the quality of the 2005+ trucks. All my other fords have been 04 or less and have been rock solid.

I think it all stems from the bad injectors. Running rich will kill cats on any vehicle.

It may look pristine, but how do you know how well it was mechanically maintained? The 3 valve 5.4 has its share of issues to begin with. The VCT system can be a nightmare, especially if the recommended oil and filter (Motorcraft 5W20 and Motorcraft filter) isn't changed frequently, and the goofy 2 piece plugs stick and break when you try to remove them.

If it were mine and planning on keeping it for a while, I'd do everything - both cats, injectors, plugs, oil and filter change.

Yeah I did change the oil right after I got it. and the VCT's are cheap to change. I have no idea what the oil/filter situation was before I bought it but from here on out its the recommended things. Ill get all of the things change out and see how she runs.

I did want to update this thread...sorry it's a bit of a necro-post.

I finally got around to updating the injectors with the latest updated part number from motorcraft. WOW what a difference. No more excessive raw fuel smell at start up and idle, no more rough idle, and i'm pretty sure I can feel a pick up in power. Next thing to do is give it another oil change because it smells of gas (also a sign of excessive fuel injection) and get the cats changed...Its taken a bit of doing, but she's running pretty strong now.