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Hi everyone,
I own a 2006 4wd Xterra with 108,000 miles with an original exhaust and cats. As you may have noticed, there have been a numerous threads lately about exploded and broken cats, some even leading to engine destruction.
At this point I am staring to get nervous about this issue. I currently do not have any CEL's or any odd noises or power loss. The only issue that I have is seemingly poor gas mileage, but I have not calculated it to see where it actually sits.
So what is everyone with higher mileage Xterra's doing/going to do about this issue? Is it prudent to simply change ALL 4 cats now with new aftermarket units? I hate to spend upwards of $800.00 or more on this job when it may not be necessary, is it possible to check the condition of the cats?
I would also be interested in utilizing the cat delete B pipes, and only running the front cats. What advantages would I gain with the delete pipes? Will I see a power increase? Will the Xterra run well with the delete pipes? Will it throw a CEL with the delete pipes?

Thanks,
Zack
 

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I don't know specifics about the X's cats, but with exhaust systems in general the thing that kills them is short trips - they never heat up enough, and never dry out and never burn the contaminants off the inside of the cats. If the catalyst gets coated with something like crappy fuel additives or such, and doesn't get hot enough to burn them off, then you can have an issue over time.

If most of your driving is short trips, then its good once a week to take it on decent road trip and make sure the exhaust gets fully heated up and can burn off the crap coating the inside of the cats. Or at least so I have been told.
 

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My opinion is having a scan gauge to monitor mpg ....if you see a change then your running rich....you can also purchase a memory saver
Module.....I keep it pluged in at the cargo area 12v socket.....
I feel that sometimes the ecu does a re set when gauge needles dip witj key in ignition....
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I'm in the same boat at Zack. 120,000 miles but no codes and getting excellent mileage. Reading these horror stories about old cats ruining the engine.

Sounds like preventive maintenance for cats is not necessary if all is well? We should ignore until we see codes, correct?


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I'm in the same boat at Zack. 120,000 miles but no codes and getting excellent mileage. Reading these horror stories about old cats ruining the engine.

Sounds like preventive maintenance for cats is not necessary if all is well? We should ignore until we see codes, correct?


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I have 116k miles on my truck and have been using the bully dog gas gt for about 4years on regular tune and I have always gotten the same gas mileage as I am getting now. 15-16 around town and about 19 on the highway going 65-70. I do have larger/heavier tires since 2009 . Before then I got 21-22 on highway. I think the gas nowadays has gotten more ethanol rich so that affects mileage too. As far as cats I have no codes and am running a good air fuel ration afaik. I amnisually in the 14s somewhere. I really think all we can do is monitor air fuel ratios and mileage.
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Unless you are using a wideband air-fuel gauge, there is no way to really tell what the AFR is. Narrowbands just dont have the capacity to accurately tell you what your AFR is. Narrowbands basically read the average and give you a guestimate.

One good way to tell if your car has been running rich or lean is to look at the STFT and LTFT tables on a scanner (Short Term Fuel Trims and Long Term Fuel Trims). Negative numbers tells you it has been pulling fuel from the fuel map and positive numbers tells you it has been adding fuel.
 

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Aha. You live in Belize. Didn't think of checking your location
You got me.

To Add to the OP, I've been getting CAT codes, but testing my 02 sensors, show that they may not be reading well and this is making run a lean mixture, I doubt that maybe my cats are bad, just too much O2 going through the CATS.. :scratch: ?

Since I don't need cats, for me it would be a better choice to get the long tubes and remove troublesome cats all together. (Cheaper than OEM Cats as well.)
 

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*Raise from the Dead*

Thinking about replacing the 2 front cats for preventive measures. After that I'll be done with every shady parts like Rad, FSU, etc.

I bought a really good X at $5k and if the engine goes because of the cats I wont put a $6k engine in it.

Anyone else has done that preventive ''maintenance''?

yeah I know I might be paranoid but I do love that thing and I wanna keep it for years.

2005 S 75K miles

Cheers
 

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If the truck has been running rich= death of the cats. I removed the cats around 110k to visually inpect them, they look brand new.
Replaced front cats around 210k+
 

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If the truck has been running rich= death of the cats. I removed the cats around 110k to visually inpect them, they look brand new.
Replaced front cats around 210k+
Cool thx for the input. Anyway of telling if it runs rich? Dark/diesel like smoke and ''bad smell''?
 

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Anyone else has done that preventive ''maintenance''?



Cheers
No. My 06 S is at 129k but cats aren't a maintenance item and I've cars with far higher mileage with the original cats so I don't worry about it.

That said if you are really that worried about it I'd say replace them, there's nothing anyone here can say that is going to remove that concern from your mind.
 

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The thing that has been killing the cats in early Xterras is the IPDM ignition relay failure. When this relay fails, it causes the engine to start, but stumble along at no more than idle while running very rich. Nissan has a new IPDM or replacement relays to solve the problem. If you encounter the above symptoms, shut down the engine and don't attempt to start it until the IPDM or relay is replaced:

http://www.thenewx.org/forum/15-how-tos/29652-how-ipdm-er-replacement-now-temporary-relay-swap.html
 

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I replaced all of mine a few weeks ago, But I did the whole system, ims, spark plugs, headers, primary cats, b-pipes and new muffler and grade 10 bolts/hardware and 4 new o2 sensors. Figured if I am going to do this all myself I'd rather not mess with rusted bolts or the possibility of needing to do the job again in a few months when the other cat fails, or the secondaries. I was quoted $1100.00 for just the two primary cats. When it was all said and done I think I came out somewhere around 1400.00-1500.00, But everything was brand new, and really easy to install in hindsight. Especially if you have a sawzall or cutoff wheel you can just cut the old exhaust off since you don't have to worry about pb blasting anything weeks before. I even hit it with a wire brush and a lot of the bolts broke off. So I just said "f it" and cut everything out.

If you didn't want to do the headers you would come in right around the $1100.00 mark, take off another 250.00 if you dont want the IMS spacer. IMO, for the price, do it yourself and you get all new hardware and a performance upgrade for the same price. All in all I think it took me around 12 hours to do all of that work. And one busted knuckle. Buy some sort of impact glove for sure.
 
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