The Nissan Path

Right bank Cat.

This is on my 2011 Xterra.
Give that those are mechanically identical to the V6 R51s I feel free to post in here.

Might do both cats same time.
What did we land on for a decent quality mid range cat for R51s?

I know Smj swears by Bosal and I'm a fan too. I also like Eastern Catalytic and the higher-end Walkers (not the bargain stuff), and lately I've heard a lot of positive scuttlebutt about Evan Fischer.

So this is odd.

WHen I had the code checked the day of this thread it did come up right side cat.
BUT they cleared the code and it has not come back since!

Now the Xterra has been sitting half the time ( as I drive my Pathfinder the other half) but in last few days I took it for a few short trips and no return of CEL.

Today I will drive it a lot and see what happens.
I guess my hope is it wont come back.
Not so much to avoid the expense, but more so the hassle of dropping the car in a shop, getting myself driven home, the agony of decided just the "bad" side or both sides etc.

Any thoughts are welcome..

palmerwmd wrote: ↑

Mon Sep 19, 2022 5:17 am

WHen I had the code checked the day of this thread it did come up right side cat.
BUT they cleared the code and it has not come back since!

Dead cat codes never recur immediately, especially when the cat is weak but not dead. It can take multiple drive cycles to pop up again until the cat is dead-dead, at which point it will start taking one or two. The cats also need to be "lit" in order for monitoring to occur, so trips to the grocery store don't count.

VStar650CL wrote: ↑

Mon Sep 19, 2022 8:21 am

palmerwmd wrote: ↑

Mon Sep 19, 2022 5:17 am

WHen I had the code checked the day of this thread it did come up right side cat.
BUT they cleared the code and it has not come back since!

Dead cat codes never recur immediately, especially when the cat is weak but not dead. It can take multiple drive cycles to pop up again until the cat is dead-dead, at which point it will start taking one or two. The cats also need to be "lit" in order for monitoring to occur, so trips to the grocery store don't count.

So I took the Car out on a nice hard interstate drive.
pushing it to 90mph on some long hills to clean out the system, then drove a bit around town.

CEL has not come back but I consider myself on notice.
When it comes back I will stop driving the vehicle and get new cats in it.

I just loathe the hassle of it all more than the expense while I am in the middle of work travel and a move soon

It depends how much catalytic material is left. Your cat may just be dirty and have plenty of metal to pass both O2 sensor checks as well as emissions tests. Cataclean and some others work great by the way.

My right cat is very dead, the CEL comes on every two or three ignition cycles. I had two different ignition coils go out on that side and it's the only side where I've ever seen a questionable spark plug at change out though, so it is far from just "dirty." If I put cat cleaner in it, it extends the duration to some hours of driving. I have a BT dongle compatible with Nissan DataScan, so I just clear it for now.

Of course I have to fix this with a California compliant cat, which means OEM. Before next July. I am debating whether I want to spend ~$600 and one day under the truck (I have lifts on base I can use, which makes this a lot easier) breaking ~19 year old bolts that have been exposed to east coast everything, or just pay Nissan $1,600 to do it in a few hours.

ShipFixer wrote: ↑

Wed Sep 21, 2022 1:34 pm

It depends how much catalytic material is left. Your cat may just be dirty and have plenty of metal to pass both O2 sensor checks as well as emissions tests. Cataclean and some others work great by the way.

My right cat is very dead, the CEL comes on every two or three ignition cycles. I had two different ignition coils go out on that side and it's the only side where I've ever seen a questionable spark plug at change out though, so it is far from just "dirty." If I put cat cleaner in it, it extends the duration to some hours of driving. I have a BT dongle compatible with Nissan DataScan, so I just clear it for now.

Of course I have to fix this with a California compliant cat, which means OEM. Before next July. I am debating whether I want to spend ~$600 and one day under the truck (I have lifts on base I can use, which makes this a lot easier) breaking ~19 year old bolts that have been exposed to east coast everything, or just pay Nissan $1,600 to do it in a few hours.

I have some affordable independents near me.
I would just let it go but am worried about the engine ingesting cat particles via backpressure and so getting ruined.

FL has no emissions.
The light came back today...

V-6 doesn't carry that risk. Don't know about the V-8...

ShipFixer wrote: ↑

Wed Sep 21, 2022 2:31 pm

V-6 doesn't carry that risk. Don't know about the V-8...

Are you sure?
I thought the VQ40de runs a miller cycle with extra backpressure too to avoid the use of a EGR

palmerwmd wrote: ↑

Wed Sep 21, 2022 2:52 pm

ShipFixer wrote: ↑

Wed Sep 21, 2022 2:31 pm

V-6 doesn't carry that risk. Don't know about the V-8...

Are you sure?
I thought the VQ40de runs a miller cycle with extra backpressure too to avoid the use of a EGR

VQ's carry that risk just like anything else that Miller-cycles, but they don't do it as frequently or infamously as VK's and QR's.

I think you guys mean Atkinson cycle It's possible that VVT shifts on the intake side equate to something like the Atkinson cycle, but Nissan doesn't advertise the VQ as an Atkinson cycle engine where they are advertising some of their current offerings as Miller or Atkinson engines. Neither Atkinson or Miller specifically rely on "back pressure," a really bad term, to work, it just happens to be that they meet emissions requirements without an EGR or similar things. There is no device or design feature that intentionally reverses pressure gradients in the exhaust, it's just fluid drag and resistance to flow.

There's a risk management rubric in aviation safety called the "swiss cheese effect" where if the slices of cheese have enough holes in them, it raises the odds that something could pass through a deck of randomly sorted slices. It's true that with enough things lined up, like a plugged cat or a banana in the tail pipe, a mechanically failing cat, and an exhaust routing such that whatever reverse pressure gradient exists will fling cat particles up above the exhaust valve train at just the same time valve overlap allows ingest.

Anyway, I don't have a plugged cat and when I tap on it, there's nothing rattling around in it. And the VQs just don't have a lot of reported cat to engine failures (that I'm aware of). I am pretty sure my other issues on that side just poisoned the remaining cat material just enough. Not going to wait forever, just needed tires and some other things more.

ShipFixer wrote: ↑

Mon Sep 26, 2022 12:13 pm

I think you guys mean Atkinson cycle

Point taken, but the trade pretty much calls it Miller whether it's Miller, Atkinson, or Jackie Gleason. Most people can identify one of the three, including most technicians.

ShipFixer wrote: ↑

Mon Sep 26, 2022 12:13 pm

It's possible that VVT shifts on the intake side equate to something like the Atkinson cycle, but Nissan doesn't advertise the VQ as an Atkinson cycle engine where they are advertising some of their current offerings as Miller or Atkinson engines. Neither Atkinson or Miller specifically rely on "back pressure," a really bad term, to work, it just happens to be that they meet emissions requirements without an EGR or similar things. There is no device or design feature that intentionally reverses pressure gradients in the exhaust, it's just fluid drag and resistance to flow.

No, it's a busted air pump, and it doesn't require a chain of events. What most folks don't get is that all it takes is one molten particle preventing the exhaust valve from closing. Then the cylinder sucks in the whole molten mess in no time flat. The "Miller" overlap doesn't directly cause it, but cat inhalation can't happen without it.

ShipFixer wrote: ↑

Mon Sep 26, 2022 12:13 pm

VQs just don't have a lot of reported cat to engine failures (that I'm aware of).

They don't, I've only ever seen a couple. I can't count all the VK's and QR's. Some engines are simply much more susceptible than others. This is the aftermath. No physics required, this is the real life result in a hapless QR:

I been driving the Xterra (aka little R51) very little.
ordered a pair of Walkers, the "daily Driver" level not the "economy" Walkers.
Also while I was at it, ordered a new Koyorad and a new Nissan OEM Thermostat (no problems with these systems just yet, but it IS a 11+ year old vehicle with 165,000 miles on it)

here is the order.
I threw some extra flanges in there. 2 times two plus one extra