3.0 cat. Inquiry

[vex3000]

I wanted to get some input from you guys in regard to a catalytic converter replacement.

let me preface by saying that I have very little automotive knowledge and probably wouldn't be doing if myself.

The car is a 3.0 usp with ~190,000. The catalytic converter code throws, and while it drives well, sometimes when fairly aggressively accelerating there is a slight hesitation. I could be mistaken here but my thought was that it may be a result of not getting enough airflow due to a clogged catalytic converter.

From what I understand on this car, I would need to get both downpipes and cats replaced, which would obviously be a pricey endeavor.

I just replaced the water pump, timing belt, radiator, thermostat, and had to get a new set of tires- so what I'm eluding to is that if I necessarily need to replace the cats I want to get it done as cheaply as humanly possible.

What route would you guys recommend? Also there's no legality issue in the state I live in.

[f0reignfeatures]

I have a 3.0 and have done some research on the downpipes/cats so I'll try to weigh in here. Just want to preface that I haven't had to mess with mine at all, fingers crossed, so this is just what I've read and heard from others.

The downpipes, unless you have ample tools and workspace, are not DIY job for the average person. You have to get underneath the entire car while it's on a lift/jack stands and drop the subframe to get them removed and the new ones installed. A friend of mine did it on his 3.0 and said it was one of the biggest pains he has ever encountered on a car, and he's been modding a very long time.

From what I've seen cheap aftermarket cats will fail within a year or so (8-10,000 miles). It seems like the point of them is just to pass inspection at that moment and then worry about replacing again later, but the labor for this car is in the $500+ range so it's better to do it right the first time.

A better (and cheaper) alternative may be going with known working used OEM ones, not the easiest to find on our cars but they're out there.

JHM makes the best aftermarket ones from what I've seen, but they're $800, and will need a $500 tune to code out the O2 sensors and run properly.

My advice is that if you don't have an emissions/smog/sniff test to worry about just leave it alone for now and save up to fix it right. Yes your check engine will stay lit but you'll know why, and you'll be working towards fixing it soon.

I know some guys do the JHM tune just to code out their O2 sensors as a way to pass inspection and deal with the cats/downpipes at a later time. Not sure how that affects performance or MPG's though because, again, I haven't done it myself. Good luck man! Let us know what happens.




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[deyrag]

First question is what codes are you getting? If you don't have a reader yourself go to Autozone or similar and have them read the codes for you. Most likely at your mileage it is a cat efficiency code. These cars have a very small threshold for triggering that code and in reality your cat is working fine (just not quite as well as the computer would like to to be). you do not say if you have an auto or manual but it is not necessary to drop the subframe with the manual trans (I have done it twice). It is not the easiest job but is possible on jack stands in the driveway.

[SJorge3442]

Plenty of people use an o2 sensor spacer to get the rear o2's out of the direct gas stream which keeps the inefficiency codes away. The 3.0 is tagged as ULEV (Ultra-Low-Emitting-Vehicle) which means the smog requriments for such a badge are hard to maintain. IMO, i've yet to see a clogged/failed cat on a 3.0 in almost 4 years of being around here. You can do 2 things. Space those o2's or get a tune and stop worrying.

[vex3000]

Thanks for the input guys. Could I get a link to a guide for installing the spacers? I'm sure there must be one around here...

[imnuts]

Unless you had a lot of time running with some sort of upset condition (lean, excessively rich, misfires), odds are that you don't have a clogged or collapsed catalyst. SJorge stated it best, the ULEVII rating is difficult for the 3.0 emissions system to maintain, so it is likely just over the trigger condition if it just started or if it is coming and going.

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[k4kwame]

After doing two treatments of BG 44k, my cat efficiency codes never came back. Worth a shot.

[vex3000]

I decided to order some 44K. Did you put it in on 1/4 tank?

[SJorge3442]

I decided to order some 44K. Did you put it in on 1/4 tank?

I usually put it a full can at 1/4 tank, drive around for a bit (~20ish miles) then I top off the tank. I'm not sure of the risks of running it at a stronger than prescribed strength, but I like running it through for a bit, then diluting properly. I usually run 44k once a year through all the cars I maintain (8 cars ranging from 2015-2001). Never had a problem, but I've almost always felt an improvement afterwards.

[G_Wagon]

Spacer for o2 sensor is the way to go...proven method

[k4kwame]

Yea, I put it in at the gas station before filling up. And then I reset the codes after finishing the treatments. I wasn't sure if it would go away on its own.

Also, don't cut any corners, your safest best is to only use premium gas from a top tier brand in your engine: http://www.toptiergas.com/licensedbrands/