exhaust *solved (plugged cat)

ejc · Post by **ejc** » Mon Jun 14, 2004 5:37 pm

Hey everyone! I'm new to the site and love the pictures. I have a 2004 crew cab. I think the truck is awsome. Question for anyone out there. Is there any noticable power difference when dual exhaust is put on the truck after replacing the stock exhaust. I haven't done it yet but wanted
to know if its any better with performance and sound.

2bunik · Post by **2bunik** » Mon Jun 14, 2004 6:07 pm

brules truck sounds really nice just to second his opinion.. I cant remember his setup but it sounds deep for a v6er. as for power you might have to ask him..

Post by **HenryJ** » Mon Jun 14, 2004 6:27 pm

Mine is a single 3" catback.
It is pretty deep as sixes go, and a little louder with out the pre-cat, although the plugged pre-cat had probably quieted it without my noticing.

It is not loud, just where you can hear it a little.

AZS10Crew · Post by **AZS10Crew** » Mon Jun 14, 2004 7:46 pm

A high flow intake will help deepen your exhaust tone also. Free-flowing exhaust and high flow intake are two mods that should go hand-in-hand.

blakeboys · Post by **blakeboys** » Sun Sep 20, 2009 10:41 pm

Bring an old thread back to life because i didn't feel the need of creating a new thread

. Well tomorrow I plan on using my new auto darkening welding mask so what better to use it on then my 2002 CC exhaust since im also installing a flowmaster super 44. SO I've been reading alot on folks removing there precat and cats but I really don't want to stare at a check engine light everyday

. The last time i was underneath my truck I believe i saw an O2 sensor going into the precat, if i remove the precat and replace it with a straight pipe going to the cat could i drill a hole and install the o2 sensor into the pipe? or will that trip an SES light? or would gutting the precat and and re installing it prevent the SES light from appearing? I have OBDII scantool computer software so i could clear the code if one should arrive but cant prevent it from reappearing and i dont want to buy one of those O2 sensor simulators on ebay. Hopefully someone could shed some light on the situation since im pretty much trying to do everything i can do without seeing the little annoying light. http://cgi.ebay.com/Universal-O2-Sensor ... 286.c0.m14

04crewvt · Post by **04crewvt** » Mon Sep 21, 2009 5:06 am

Our trucks downstream O2 sensor is located past the end of the cat, there is no sensor for the precat so you can remove it without any need to cheat the OBDII system. No light will light and no code will be set. I do not recommend removing the cat, we have a high flow unit from the factory and you will get little gain from removing it (and possibly a lot of legal hassle if caught).
You can either add a straight pipe where the precat was or pull it, hollow it out and re-install and you should be good to go.

blakeboys · Post by **blakeboys** » Mon Sep 21, 2009 5:13 am

Sweet

Ill remove it all together then and straight pipe it. But either way I never really intended removing the main cat since i seen too many posts where HJ said " it's a high flow cat". Another question: Would the exhaust sound better with a cat back straight pipe, no muffler or better with the flowmaster?

04crewvt · Post by **04crewvt** » Mon Sep 21, 2009 5:30 am

I personally would go with the muffler, it sort of tunes the exhaust note and I really find straight pipes are just too loud/obnoxious. Heck I still can't justify modding my factory setup it sounds fine to me and if I wanted big sound I would have a V8 (like in my Tahoe). I really do not see the big deal about loud exhaust unless it's on a muscle car or hot rod which are supposed to sound like they have some _alls (same goes with stereo systems that you can hear from a mile away). I prefer to keep my hearing as long as possible where a lot of 20somethings are going to be needing hearing aids by the time they are 40.

blakeboys · Post by **blakeboys** » Tue Sep 22, 2009 8:59 pm

Well I had my brother go buy the 2 1/2" piping for me but when he came back the pipe he had was 2" so instead of driving back up town i decided to just cut a hole in the bottom of the precat and bang all the junk out and weld the piece back in

well all went well and after driving it for a day we got a problem! My truck will not go over 55mph and will just wind up to 4k rpms n make a vibrating clicking noise sounding like its coming from up front.... i tried WOT and twice i had the SES light appear then disappear. SO I checked the fluids real quickly and all was good then i plugged my computer into the truck and got a pending DTC "P0101 -- Mass or Volume Air Flow CIrcuit Range/Performance Problem" so I searched around but couldnt really find a solution since my precat was now gutted... could a piece have lodged itself into the main cat? or could there be water in the distributor cap? HELP PLEASE!!!!!!!

UPDATE: I removed the MAFs and carefully cleaned it with rubbing alcohol and q-tips. The truck still runs the same and i notice that when im cruising at about 45mph then WOT it goes to exactly 3000 rpms and the speed slowly goes down.

04crewvt · Post by **04crewvt** » Wed Sep 23, 2009 4:41 am

Sounds like you may have plugged the Cat and you are now getting too much back pressure. It would at least be where I started to look. With luck you can remove the obstruction and be good to go without having to pony up for a new cat.

F9K9 · Post by **F9K9** » Wed Sep 23, 2009 5:02 am

04crewvt wrote:Sounds like you may have plugged the Cat and you are now getting too much back pressure. It would at least be where I started to look. With luck you can remove the obstruction and be good to go without having to pony up for a new cat.

X1! The honey comb in the precat is pretty tough to get out. Since you can weld, why not remove the cat and see if the entrance is blocked, shake it out and replace?

blakeboys · Post by **blakeboys** » Wed Sep 23, 2009 10:12 am

04crewvt wrote:Sounds like you may have plugged the Cat and you are now getting too much back pressure...

Ok I guess ill pull it out and check but wouldn't i get a different dtc instead of P0101?

04crewvt · Post by **04crewvt** » Wed Sep 23, 2009 10:36 am

Possibly but 1st things first, since you did something to the exhaust that has a probability of causing a problem with air flow I would check that before I guess at a totally different reason for the issue.

I had a cat plug completly on another car and the symptoms you have at higher speeds/RPM is what I had for symptoms.

s10 again · Post by **s10 again** » Thu Sep 24, 2009 9:29 pm

Watch the temp gauge a plugged or partly plugged cat can cause a rapid overheating problem. It is possible for dust from the busted out pre cat to clog up the main and you may not find a big piece blocking the main cat. If it looks ok then you might test pipe it and see if it needs replacing.

Chris.

blakeboys · Post by **blakeboys** » Sat Oct 10, 2009 1:16 pm

It'd probably work however, from wat I've read the o2 sensor near the air intake does much more random and precise signals to the ecu I think if u did hook this up I'd really effect ur performance

Post by **HenryJ** » Sat Oct 10, 2009 1:16 pm

blakeboys wrote:Sorry it took so long for a response, just got time today to put everything into action. After suspecting the catalytic converter and hearing everyone's suggestion to check the cat i decided to do away with it. I cut a a small section away on the bottom of the the cat with an angle grinder then chiseled all that junk out and blew it out with a blower then welded it up with a welder. I started the truck and all i can say is OMFG!! my truck actually sounds like a truck, nice rich deep grumble sound, thanks to the flowmaster super 44. After the test drive my truck appears to have better acceleration, torque, and hopefully mpg...but we'll see. Thank you everyone for your suggestions and expertise.