Catalytic Converter

[slybydesignq45t]

Ok, I think I have boiled my metal ball tin can sound down to the cats. I get more then the average amount of exhaust threw my pipes as well. So I most likely wont pass smog till I change them out. I went to Joe's website but did not see any options for new cats. I saw on Magnaflow makes universal California Cats for $100 a piece, what you guys think?

[Q45tech]

Our experience is that low cost aftermarket cats only function for about 1 year - 18 months and don't perform well in converting HC and CO2.

Designed for those who need to pass a test to sell car.

[slybydesignq45t]

I have been doing some research and will be replacing the O2 sensors as well. What do you recommend in both categories?

[bullittandy]

Our experience is that low cost aftermarket cats only function for about 1 year - 18 months and don't perform well in converting HC and CO2.

Designed for those who need to pass a test to sell car.

I had a Magnaflow x-pipe on a Mustang for 3 years before selling. I've been on several Mustang boards and can't remember anybody ever complaining that an aftermarket cat caused a emissions failure (unless it dropped the rear O2 sensors) but because of a bad cat-no.

You must be referring to the muffler shops on Moreland or Memorial drive.

[qship96]

Ok, I think I have boiled my metal ball tin can sound down to the cats. I get more then the average amount of exhaust threw my pipes as well. So I most likely wont pass smog till I change them out. I went to Joe's website but did not see any options for new cats. I saw on Magnaflow makes universal California Cats for $100 a piece, what you guys think?

Dont ASSUME it wont pass, go thru the test before wasting money on new cats. OEM {NTK} oxygen sensors are only $100 for the pair at http://www.sparkplugs.com or about $300 from Joe.

[maxnix]

I get more then the average amount of exhaust threw my pipes as well.

Could you elaborate upon that statement?

Nissan and Lexus catalytic converters have a much higher percentage of precioius metals, hence never fail unless abused. They did cost about $1,100 each before precious metals rapidly appreciated recently. I was talking to a tech the other day about how bad and short lived the big 3 made theirs.

[Q45tech]

Don't confuse the robust cats of 90-93 with the different cats of 94-95 and the OBDII 1996 cats.

[qship96]

My 96Q original Cats are functioning fine at 221,xxx miles.

[Q45tech]

Don't assume that just because OBDII doesn't throw an O2 code that the cats are performing good enough to pass an actual MEASURED dyno emission test.

Nissan and many others had serious problems zeroing in on sensitivity until about 2002 when they installed wide band O2 sensors.

So 1996-2001 were given an almost free ride as far as pollution was concerned. The cats could be 50-75% dead and still not throw a code if they were warmed up enough....................Cold start emissions failed on a dyno where the actual exhaust was totally bagged and measured.

[Rex]

I'm pretty sure qship is still having to do emissions testing in MD every 2 years ... I can't imagine they've lessened the frequency.

[slybydesignq45t]

Q45tech, I think you hit it on the nose. I researched symptoms of a failing or failed cat. When my car was on the lift everything was bolted down good, bushings looked good, hoses looked good and tight. So I could not not figure out what that metal ball tin can noise was. I did some research and found that the noise could be from a bad cat. It only happens when idling, or going in reverse. I don't think my cats are totally shot or not I wouldn't be able to drive if they where fully clogged.

As far as me saying a little more then usual exhaust threw my pipes, when I first purchased my car I had 0 visible exhaust out my pipe. Once it got cold I can see the exhaust, which most say is normal, but I assumed it should go away after car warms up with that said, I also notice it comes out slightly thicker then other cars, not so much to make me worried, but enough to make me notice it. The mechanic looked at it and said it still must be cleaning itself out from the throttle body cleaning I did a month ago or so.

This is about the same time the tin can rattle sound became more prominent. That was one of the reasons I had the throttle body cleaned. I have tried passing smog twice and both times I failed do to two different reasons two different times. This time it was my NOX reading. After working with some mechanics we all agree its going to be the EGR witch did fail a pressure test and or one or both my cats. If I replace one, I might as well do both and the O2 sensors. Plus even if it is just one of my cats about to fail I hate that rattling noise and its kinda embarrassing driving a nice car and on idle that rattle noise makes people look at you.

[Q45tech]

Sure it's not a broken rusted cat and exhaust pipe heat shield?

Most STATES don't do a dyno test on 1996 and newer vehicles they just plug emission computer into ecu......................relying on ecu [secondary O2] to test cats - not an actual measured from exhaust system.

[Rex]

Most STATES don't do a dyno test on 1996 and newer vehicles they just plug emission computer into ecu......................relying on ecu [secondary O2] to test cats - not an actual measured from exhaust system.

Great point, I never had a 96 (& up) tested in MD .... well anywhere actually. Though my co-worker had his 96 9or 97) Maxima fall off the dyno tester here in Ohio back before they did away with testing in the Greater Cincy area.

[Denver90Q]

Sure it's not a broken rusted cat and exhaust pipe heat shield?

Most STATES don't do a dyno test on 1996 and newer vehicles they just plug emission computer into ecu......................relying on ecu [secondary O2] to test cats - not an actual measured from exhaust system.

Colorado does dyno test. I just had it done on my 1998 Frontier which failed miserbly due to bad cat. Truck was well under standards after replacement with aftermarket cat. The shop that replaced it said that pieces of the cat had come loose and went into muffler and suggested I replace the muffler as well? Also stated that OBII on this model year was not set up to measure emissions?

[slybydesignq45t]

My car is a 94 so they run the test from the pipe. I think I may be able to pass if I just clean the EGR valve, but in any event I am going to want to get rid of that nasty rattling noise. I will drop the cake for the cats, but I will do aftermarket cats. I can't afford OEM cats at the moment, if the Magniflow cats will last me two years then for the price I can't beat it. Also had the car on the lift and the heat shields were fine, sturdy no loose bolts or anything. I also tugged at the pipes, they too where on solid.

[Q451990]

How about a full exhaust system from a lower mileage junkyard car? Cat failure is pretty rare...

Heath