I have a 2001 Ram 2500 with the 5.9L V8, With about 93k mi
Recently the mpg has been dropping, and it now has a rough idle at
startup. The cap, rotor,wires were changed about 10k mi ago, plugs
were changed about 1000 mi ago. I'm going to take the TB off thurs
and clean it and check the plenum gasket. I temped the pipes before and
after the cat today and the front was anywhere between 20-50deg higher
in the rear. Temp was taken after driving to get temp up, stopping truck
and taking temp while idleing. I read on here that rear needs to be higher.
Does it sound like cat is going bad??

If it is bad how does this look for a replacement?? http://tinyurl.com/34rsaz

 

the temp is a way to test, but it isnt certain...but it is likely. take it to an exhaust shop to get a pressure test on it. explain the situation to them and they should be able to tell you.

 

p.s. if you are in cali, that might not meet emissions, I am not sure about cats all together, just letting you know my personal experience.

 

I'm in Virginia, No sniffer tests here yet. I forgot to add, when the truck is at idle
it sounds as there is something blocking the exhaust when you listen at the tailpipe.
Almost like the same hissingsound you get with a leaky exhaust. I've got a stainless flowmaster
50 series muffler with 3" out, The stock 2.5" from the cat to the mufler. I covered the
pipe and no leaks. There is no rattle in the cat or muffler.

How much does the pressure test usually run? Might be better just to get the high
flow cat and put 3" pipe all the way back.

 

i think mine was only like 30 bucks, dont remember though. the high flow cat might now be a bad idea.