Exhaust rattles, creaks, pings as it heats up. Suspecting bad cat.

Driving around normally a few days ago, I noticed an awful ping/creak/scraping sound coming from the very back of the vehicle. It is hard to hear from the outside, because it only makes noise when the exhaust is HOT. This can be from 10 mins of regular driving without stopping or a solid pull. Once the car stops for more than 60 seconds or so, the noise goes away until it heats up again. It is constant and easily reproduceable, though it comes back at varying degrees of severity and disappears quickly when you stop the vehicle. During the stopped cooldown period, shifting into P/D/R agitates the part somewhere and causes it to ping.

I've inspected my Thermal 3" and heatshields on the underside of the vehicle, and can't find anything that may be contacting the vehicle. It sounds like it's coming from the right muffler, and I am suspecting a cat is cracked or loose. The puzzling part to me is that the component is only making noise during high heat events.

Just wondering, has anyone had problems with their cats on the 22's? I'm at 8000 miles and just added a ZFG 91 tune about 1,000 miles ago. Stock downpipes, aftermarket 3" Thermal and Thermal flexpipes.

Taking this to the dealer, will update.

Edit: I wasn't able to capture the sound myself, but I found a video that is almost an exact match for the sound I'm having, though mine is much less severe:

Wow...it sounds like the video? What's going to complicate things is your aftermarket exhaust. Hope it goes well at the dealer!

Maybe 10% as bad as the video, and it very strangely goes away when the car is calm. Wondering if the cats can become loose without breaking. Gonna be expensive if they give me crap about my exhaust. Expecting they will

I'd say 99% chance the dealer is going to blame the Thermal, just so they don't have to pursue warranty work with Ford. It could be a chunk of the cells in one of the cats has broken and is bouncing around. There are two sets of cells per cat, so if it was the upper then the lower cells are preventing it from coming out. Even if it was the lower cells there are many obstructions in bends/mufflers/resonators that could prevent it from coming out.

Then again, could be something else.

Thanks for your insight about the cats, didn't know there were 2 cells. It's definitely going to be tough to convince the dealer with the exhaust on there, especially if they find out I tuned.

It better be a damn good reasoning for why your aftermarket exhaust would cause, lets say a cat cracking apart. In my state, the dealership needs to prove how an aftermarket part caused a malfunction of why you at the dealership, not just state the aftermarket part is at fault thus they don't need to cover with warranty work. Hopefully you are just another person with a cat issue on an Explorer ST.

I have rattling from my exhaust when its in drive, or reverse, and I am holding it at a stop but I believe its the mid-pipe issue I have seen on the Explorer ST. I take mine in Thursday.

May have found my problem. Exhaust seems to have backed off quite a bit. Gonna hit it tomorrow and torque the hell out of it.

Interesting. Let us know how it turns out ...

Got under it today and snugged up everything. The midpipes had moved quite a ways off the downpipes. Vibration sounds a lot better, but is still there and quite annoying. At this point I am convinced that it is not a cat, since I partially fixed it. Need to get back under there and check my connections, the new higher-pitched sound almost sounds like 2 sections of the exhaust pinging together inside the clamp.

There is very little clearance between my rear diff cover and my Thermal 3". I'm suspecting that during hard acceleration, they may me colliding and slowly bumping the exhaust back off the downpipes.

Should I leave a little space between the pipes inside the band clamp to rule out 2 pipes colliding inside the clamp during thermal expansion?

Still going to take it to Ford... Could still be a loose heatshield around the downpipes, which I'm unable to get to and inspect.

Been driving myself crazy with this. Turns out I've been attacking two separate issues the whole time. I fixed the primary annoying sound coming from the exhaust by re-snugging everything up. What sounded like a heatshield rattle persisted, and I spent more time under the truck than I care to admit. Finally found a loose panel on the liftgate... the panel was never fully assembled and there is a piece of metal or plastic floating around in it.



I was able to push those tabs in, but I'm taking it to the dealer to fish out whatever is rattling around back there.

Here's a summary, to date, of small problems I've had with my '22 ST purchased in April, new.

1) Liftgate not fully assembled; panel loose, floating plastic
2) Front dash trim not fully installed, loose plastic above USB ports
3) Driver side front ABS sensor nearly fully backed out -- I don't know how I wasn't throwing ABS lights.
4) Passenger rear fender well trim pieces not flush with body, probably missing clips or adhesives.
5) Passenger side roof rail not flush with body, protrudes from windshield.
6) Passenger side front seat - leather pops out of trim pieces. Plastic clips for trim pieces are installed on one side, but not clipped in. Outboard side is missing the clips entirely and constantly needs re-tucked.
7) Fuel tank screws loose, not fully installed.
8) Loose hose after FORD oil change, engine oil everywhere in my engine bay.
9) Ford bent 2/4 of my pinch welds during same oil change.
10) TBD... I'll find more.

I paid $63k out the door, feeling kind of upset with the QC here, even though I understand the assembly lines are a mess -- especially during the pandemic. Some of the stuff is so minor, it's hard to care much, but with loose ABS sensors and a cumulative effect, I'm becoming disenchanted. Love driving her though, just want to get all this nonsense fixed.

Wow, and some other people have reported no issues.

I sense another Poll coming ...

Haha...
Now I just need to install my AWR brace before that becomes an issue too

what hose is the dealer messing with for an oil change? I swapped out my OEM drain plug for the UPR, makes oil changes a breeze.

Well, if you're going to push 500+ hp then that's probably a good idea!

Otherwise, the poll I conducted here (along with FORD's own data) suggests you're good to go.

In the mean time, I hope you get all the small stuff sorted out.