2003 Discovery 2

I had been getting a code for a Bank 1 Sensor 1 faulty O2 sensor for awhile (and ignoring it). Recently, the CEL began flashing and the exhaust started smelling extremely rich and the truck felt like it may be misfiring.
I immediately replaced all O2 sensors and plugs.
I skimped on the O2 sensors, and the front two were reading 0v, so I purchased Bosch and replaced the front. Nothing has changed and I am getting the following codes and live data readings:

P0150
P0305
P0304
P0306
P1300
P0300
P1171
P0171
P0332
P0130

O2 Sensors
1/1 0v and shrtft 0 (but it did jump up to 25 multiple times and back to 0)
1/2 .895v and shrtft 99.21%

2/1 0v and shrtft 0 (also jumped to 25 and back to 0)
2/2 .855v and shrtft 99.21

TPS 0%
MAF 7.91 g/s
spark advance 19 OBTDC

STFT B1 0%
LTFT B1 25%
STFT B2 0%
LTFT B2 25%

Ideas? Thanks!

 

You have catalyst destroying misfires on cylinders 4, 5, and 6 and nonspecific misfires. Among others. Those are the ones I recognize. You'll have to fix your misfires, probably replace your cats.

 

I agree with that. Cats are done. But why? Are you losing coolant or were you having misfires all of these codes happened? I had cats go bad on another vehicle and learned I had a bad spark plug so gas was essentially going into the exhaust. On my rover I had that issue but it was head gaskets (coolant steam into the cats). If you don't figure out the issue, the new cats will go bad too.

 

I was not having any misfires until this happened. The only code I was getting was for the faulty O2 sensor (Bank 1, Upstream). About a mile into my drove home, CEL began blinking. I pulled over, and got the O2 codes and a misfire on Cylinder 5. At this point I noticed the exhaust was extremely rich.
I gently finished my drove home (about 2 miles), ordered 4 new O2 sensors and all new spark plugs. After installing, I cleared the codes and went for a drive. The CEL was immediately flashing, and it took a few minutes for the above codes to begin to pop up.

 

Definitely following this thread because I have been having the same issues.

 

When my Titan had the same problem I'd been told by the dealership that I needed a new engine. I said screw that and had it towed home. I put it in time out (on the street) for two weeks then limped it up to the garage, dropped the Y pipe and started the engine. It ran fine (I didn't drive it. Super loud and would probably catch on fire after burning the valves, so it was a short test). So I stuck a long screwdriver... oh forget that part. Anyway that's how you could easily diagnose the major problem. After clearing the obstruction (first cat disintegrated into second and clogged it) I hooked it all back up and it ran great. So then I checked the codes and found a single cylinder misfire, which led to the bad spark plug. Five years later it still runs like a scalded dog and gets better gas mileage to boot.

If you aren't losing coolant I'd drop the Y pipe, run it very briefly at a stop and see if the engine will go, then work your way from spark plugs to wires to coils to harness to computer.

You'll almost surely need a new y pipe with cats unless you can weld and find cheapo cats. FWIW I have the cheapo Davico Y pipe from eBay and it works great.

 

I'll do drop them tomorrow evening and thank you, sir. As for the plugs, wires, and ignition coils-all new.

 

Welders? Got em. TIG, ARC, MIG, Plasma. As well as stainless steel pipe and hydraulic benders. Not a pro by trade but definitely handy at all of it. Yeah, the Cats and muffler has the "Land Rover" Stamp on them. So, definitely time for a new install. I bought this disco 4 months ago and the owners before did little to nothing to maintain it. it has 87k miles on it now and it was cheap. So, I bought it. Looks like the one in your picture.

 

If you can bend and fit your own exhaust you might want to search for a thread on headers. Summit has some super cheap, about 215 dollars, for Disco II (verified to work in thread) and you might be able to substantially upgrade your exhaust for the price of a premade Y pipe.

 

Instead of a Y pipe, perhaps dual exhaust is the better option (increased flow of the exhaust)?