Lately I have heard some rattling around the CAT and have been thinking about deleting it, but am worried about throwing a code or screwing something up. I am not expecting great gains, but with my 3.9 I'm thinking anything would help. Any thoughts or ideas would be greatly appreciated.

 

Why bother? Vir-tually no gain in performance (modern cats aren't terribly restrictive.) Plus you increase the NOx & Hydrocarbon emissions of your truck.

IMHO, messing with the cat and emissions controls is pretty piggy.

 

You might throw a code for catalyst efficiency.

Around here they also do a visual inspection.

 

Don't know about MN inspections regulations, but you would fail in NY for a missing CAT and probably emissions OBD would fail also. So check your state regulations before removing it.

 

If you get rid of the cat, what would you plan to do with the oxygen sensors? If you just disconnect them, you'll get Diagnostic Trouble Codes DTCs) relating to improperly working sensors - in many places, that's enough to fail an emissions test/inspection, even without seeing that the cat was gone. To fool the computer, you'd need to design a circuit to replace the sensors that would generate the correct output - not that hard to do, but the visibly missing cat would fail the inspection. Some areas also use the exhaust "sniffer" that will test for pollutants, so even if you bypassed the sensors properly and hollowed out the cat, you'd still fail based on sniffer results.

 

If you don't have to worry about emissions then I'd do it. I did it on my truck and I love the sound/butt dyno increase. But mine was busted/rattling pretty bad so it really decreased flow.

I pulled my O2 sensor out of the pipe and just zip tied it to the frame, no CEL. But with my muffler it can be loud around town, but then again I like that!

Trucks before 2000 had a different set up, so just like my 98-your 99 wont throw a code as long as you keep the O2 sensor plugged in. But as the others have said, you will not pass inspection.

 

yep, you're lucky. pre-2000 can just zip-tie to the frame, post-2000 tests the sensors every now and then by running deliberately rich/lean and seeing if the O2's respond. (Or that's what i've been told)

 

Thanks everyone for the responses. Fortunately for me, I live in a state that does not require inspections...at least for now. I guess I am really tired of hearing the rattling and would like to do something to end it. I am on a slim budget with my truck and need to make repairs as inexpensively as possible. This forum, and all of you have been a valuable asset in that regard and have made a great difference as I have very little mechanical experience.

 

I was in the same boat...I didn't want to pay some one to weld in a new cat at about $250 so I just got two pieces of pipe with a few pipe clamps. Cut out the Cat, and replaced with pipe. Total project took around 30 minutes and about $25 total. Best of luck to yea!

 

best to replace it yourself around $140 or less in parts just clamp it in a weld is better but clamps work ok.

Brian in Tucson I agree

wow have they gone up two years ago you could get one for less than $90

The one for my 2.5 shows $170 to $200 that's a big jump in price

I have also noticed the same tires I now have from 5 years ago cost $40 more a tire that's a 70% jump in price some economic recovery thanks Obummer