'08 2.7L 4cyl Taco exhaust/flange leak/rattle and no pressure at highway speed

Having difficulty diagnosing an issue with a 2008 2.7L 4-cylinder Tacoma. Started hearing a rattling noise/loud exhaust on the freeway, accompanied by not enough pressure to stay at freeway speed (50~ mph).

Got it home, started listening/looking, and found that where the pipe flange/gasket is located before the manifold was rattling. Bought a new donut/flange, installed it, and it was still rattling and had no speed. Even replaced the springs/bolts at where that flange is located, and they are still rattling, with no speed.

Next guess is - potentially something is plugged up? Should I be looking at a clogged cat?... what's the likelihood it's a clogged muffler?

Or... could this be a stuck injector system switch valve? That doesn't seem like it would cause the loss in pressure/ability to stay at highway speed...

Any thoughts out there?

 

Same engine and year truck as you. My factory Cats finally kicked the bucket around 175k miles. The mesh inside had broken apart, CEL on and no bad side effects for a while but eventually I was losing a lot of power on the highway.

Had both cats replaced by a local muffler shop, truck runs strong as ever now. You should be able to remove your heat shields and hit the cats with a rubber mallet while the truck is off and hear a rattle! Mine would rattle like crazy and make a sucking sound anytime I revved over 3500.

 

Agree, sounds like a clogged cat. This is easy to diagnose, search youtube.

 

Yep, it was the cats. Got the power back and then some. but lost $2k. haha

 

Goodnight! I feel like you got robbed! When I had mine fixed a year and a half ago it was 800 for parts and labor but that was at a local muffler shop in a small town. He cut the old ones out and welded the new ones in.

 

Bought OEM cats from the dealership and did the work myself... robbed? Probably, but fingers crossed I won't have to replace them again for another ~15 years.