Need Some Assistance With Catalytic Converters

[5523Pathfinder]

Just cleaning the Air flow meter may not cure the problem, as when i have seen it, its not a dirty situation. Usually what i do is look at the MAF sensor output with the enigne off, at idle, and at 2000 rpm. Usually the dead giveaway is it will read near or over a volt with no air moving(spec is .5v or less). I also looked at the load precentage under heavy accleration and would see the numbers skyrocket.

 

This is why i asked earlier about what information they gave you on how they came to the conclusion that both your cats were bad. They should be able to explain how they came to their diagnosis, thats what I do. This would be a perfect example of the failure not being the actual code. They need to properly diagnose it and no just break out the parts shotgun!

Edited October 16, 2014 by 5523Pathfinder

[AirChime]

Sorry I havent updated anything, but there really isnt anything to update. I have been working long, tired hours, but I did order the correct 4 O2 sensors. I figure for the $270 spent, if they solve the issue, that great. If not, they probably needed changing anyways. My neighbor, who is the son of mechanic shop owner that dealt with Nissans, Toyotas, etc is going to help me install them.

My question is if they dont solve the problems, and it is the Bank 1 and Bank 2 converters, which ones are they?


I scored a couple of locomotive ditch lights at an auction this week. Your LED lightbars will weep because of the output and throw of these.

[fixinto]

If you have both of those codes at the same time, there has to be a common failure. Its very rare to have two cats on different banks go at the same time. I have reparied many of these and I will tell you what i would do. I would inspect the air flow meter. I have seen where it reads too high in its signal range without setting a check engine light. Basically, its telling the computer it has a lot more air coming in than what actually is. This in turn is making the o2 sensors read that there is either too much or too little oxygen left over after the combustion burn. The p0420/p0430 are catalytic efficiency codes, not failure codes. My money is your cats are not bad, but your air flow meter is(or you have a vacuum/air leak).

or someone had a vacuum leak or bad air meter for a while and the cats got fried by the extra fuel the motor put out. happens all the time. on the same note, i would at least check the o2s heater voltage and V ref while its running. you can also temp check before and after the o2 aand see if there is a large difference.

If your ride is burning oil that will fry the O2s and more than likely the cats too depending on how much oil its burning. so while not probable there are several things that could cause a double cat failure. Luckily i live where they dont test so when i suspected my cats were toast. i hollowed them out with a counter sink bit. she feels like she is breathing better now.

 

pat

Edited October 27, 2014 by fixinto

[fixinto]

the bank one and bank 2 cats are directly off of your exhaust manifolds. i highly recommend testing some stuff before throwing too many parts at it, because you can get into a high dollar situation and still have the problem very quickly. so much so, that it would have been better to take it to a reputable mechanic. a little research and youtube should cover the basics on how to diagnose and replace the correct part or parts in this situation. its awesome doing your own work, and getting that sense of satisfaction when you replace parts and fix something, but that feeling goes up quite a bit and u save bundles of cash by troubleshooting it and replacing the proper parts to repair it straight away.

 

p.s. there is a link to get your FSM somewhere on this site, i recommend that too, it will break everything down to exploded views, torque specs and even some flow chart stuff. goes a long way when you can have multiple parts for the same problem.

 

hope this helps you out some

 

 

pat

Edited October 27, 2014 by fixinto

[fixinto]

I forgot to mention that I will be changing the O2 sensors out. Am I correct in assuming there are 4 of them?

 

Your thoughts on these:

 

NTK Upstream Left: http://www.rockauto.com/catalog/moreinfo.php?pk=1643118&cc=1431977

 

NTK Upstream Right: http://www.rockauto.com/catalog/moreinfo.php?pk=1644020&cc=1431977

 

NTK Downstream Left: http://www.rockauto.com/catalog/moreinfo.php?pk=1644446&cc=1431977

 

NTK Downstream Right: http://www.rockauto.com/catalog/moreinfo.php?pk=1644672&cc=1431977

 

im not sure about the 04, but the 96 there are 4, 2 pre and two post cat. the pre control your air / fuel ratio, and the post make sure the cats are doing their job.

 

pat

[AirChime]

OK, today I got two of the o2 sensors, and they were a bit of a pain in the arse. It turns out the two I replaced the two downstream sensors. I dont know much about O2 sensors, but these were coated black with baked on gunk. I'll take a pic later, if you care.

I tried changing the two upstream sensors, with absolutely no joy. I even rented an O2 sensor wrench from Autozone. I can get the wrench on it, but I cant turn it. I noticed the box for said O2 sensor says its for Fords, so that may play a role. I will stop by Autozone tomorrow to make sure they dont have a Nissan specific wrench. I would appreciate any other suggestions or techniques.

[AirChime]

Oh, one other question. After I get the two upstream O2 sensors changed, and if that is the problem, what do I do afterwards? Do I disconnect the battery and reset the computer, or do I just drive it to Autozone and have the codes read again? With my Ford I had to reset the computer by disconnect the battery and after reconnecting, I had to drive it for 75 miles. Given the current transmission issues, I am leery about driving it at all.

[AirChime]

Man! After a week of messing with them, I still cant seem to get the upstream O2 sensors out. I can slip the socket onto the upstream right O2 sensor, hook up some extensions, but I cant get the damned thing off. I dont know if the socket isnt on the sensor all the way on the sensor or what, but I am frustrated.

So I ask again, does anyone have a technique to get these things out?

[fixinto]

Are you using an O2 socket? helps a lot, and be sure you have enough leverage to get a decent bite on it to break it loose. dw40, pb blaster or some kind of penetrating oil to help you along. spray it around the base where it threads into the manifold. If something is in your way, take a few phone pics to see how everything looked before you jacked with it, then remove whatever is keeping you from getting where you need to go. "most times it is easier to give yourself room than to try to work around things"

if the angle is wrong and you cant get a good bite, get an extension that swivels so you can get a better angle. Thats about all i have for you bud. FSM, and think it through, take your time.

 

 

pat

[AirChime]

Yes, I am using an O2 sensor socket.

There are all kinds of hoses, both metal and rubber, in the way. Even if I remove some of the hoses, there still isnt much room down there. I wonder if I remove the heater hose, or whatever its called, if that will introduce air into the line (thus causing bubbles) and lead to a whole new set of problems.

[fixinto]

ya, DL the FSM, it will show u step by step how things come apart and such. I would say ur Power steering fluid tank, is in the way, your PCV, hose on the side of your intake, the coolant line on the side of your intake, your evap charcoal canister, and the metal pipe running from your exhaust manifold to the EGR valve is in the way. Only reason i know is because i replaced mine last year. ;P take all of that off, or loose, relocate it, slide it down or move it over or w/e you need to do to get in there. There isn't really a whole lot i can tell you other than, extensions and take your time. think it through. Sorry i cant be of more help.

 

Pat

[R3DN1CK]

Those cats do go bad... we sell them. The front ones self destruct and plug up the back ones. The front ones are "cats" the rear are considered "resonators" but both have cats...

[AirChime]

Problem solved. Problem staying solved!

 

 

I hit both O2 sensors with PB Blast every few days, and waited for warmer weather. Today I tried, and they came right off. No fuss. THey are in terrible shape. There's no two ways about it, they were destroyed. I will get some pics up later tonight after the Cowboys lose and I am done screaming at them through them TV.

 

R3DNICK, what are yall getting on the cats? Got any deals?

[fixinto]

nice, happy to hear it worked out for you man.

 

 

 

Pat

[AirChime]

 

Downstream are on the left

Upstream on the right

[AirChime]

Cats changed, turns out it was the upstream cats on both sides. Transmission shop changed them for free when they serviced the transmission. I also got a good warranty with all the repairs.