So I just started driving my truck again after 11 days in the hospital with a bad case of appendicitis. I was reminded again of my truck's lack of power and bad fuel mileage when I began driving it again this past week.

Today, out of nowhere, my truck started bogging. I blocked all sorts of traffic on the highway getting home, doing 20mph, since my truck was shifting funny and I couldn't get up to speed. That was a fun drive. I get home and immediately notice my truck lost its rumble. I tried hammering on the cat, but no go. Since I can't be doing anything too strenuous, my dad crawled underneath it and pulled the O2. Fired the truck up and it was like a whole new truck. It was loud, but damn did it run better. Gonna gut it tomorrow. Hopefully my mpgs go up from the 10-12 I'm getting now and maybe I'll get some power back. Glad to be back on the forum. Any tips?

 

cut it off and weld a Y pipe in, drill a hole in the Y pipe and weld in a nut large enough for the precat O2 sensor to fit on.

Or just take the cat off and take a lead pipe or a piece of Rebar and stab the **** out of the endside and break up the honeycombs and dump out whats left of it.

Have you done your plenum fix yet, if you havent it might be the reason why it got clogged up in the first place.

 

heres how i took care of my cat....... gutted cat is fine tho, but will cause some funky turbulence in there thats prob not good for flow

 

your MPGs are actually pretty good if your getting up to 12...most get 8-10.....Do the plenum, tune-up, and timing chain.....i have 201K on my 5.9 and im currently getting a consistant 14 mpg city. I dont beat on it though. and i have 4.10 gears

But do the plenum, thats the best thing you can d to try to get more mpgs (aside from the cat)

 

Ditto on the plenum. I did mine and as 95RAM360 said I was getting about 10 or 11 mpg. now im gettin close to 14. usually it's about 12 around town. But a lot better than the 9 before. Sounds to me like I need to check my cat too. I lost my mojo....... I mean rumble. I also have a hole somewhere but I'll figure that out this week.

 

Well the thing is, I put in an M1 manifold that my dad and I snagged with a 408 that needed work. My plenum was shot, so I went head and installed it before we fix the 408 up.
I figured the cat wasn't perfect for a while, since even with the new manifold, my performance and mileage wasn't great. I suppose it was only partially clogged at the time and since has only gotten worse. When I checked the exhaust flow from the tailpipes, all I could feel was heat and a very, very slight flow of exhaust if any.

 

mine was gutted before I got the truck, they cut the side of the cat open, ripped the junk out, and welded er back up.... might be easier than takin it off to do it....

it has a bit of a hollow, 'tinny' sound under load but not that noticeable

 

Does anybody know or has anybody ever heard of thermally cleaning the Cat? What I mean is adding some sort of additive to the fuel and driving for a couple hundred miles straight, like on a long trip. Long enough to get the cat hot and burn out all the crud that's gunking it up? Maybe an additive with oxygenates and something like Diesel fuel to get the exhaust gases nice and hot.
I'm not recommending this, just wondering if anybody has heard of or tried it.

 

I think its "snake oil". The cat gets plenty hot when it clogs up, sometimes glowing red, and if that doesn't burn up the "crud", then I wouldn't know what would, short of melting the sucker.

Hollow it or get a high-flow. Thats my two cents.

 

Well the deed is done. My truck runs 100% better. Its got a bit of a louder exhaust note, but nothing to complain about so far. No CEL yet, but we shall see.