This is an 03 with 150k miles. I picked it up cheap needing a heater core, but it is also running poorly. It starts great, and when driving is very powerful and smooth, but it idles like a drag racer on a cold day. I pulled the codes and it has a ton. It allegedly just had all the o2 sensors and plugs and wires done. I just put in a new MAF sensor, the appropriate bosch.
Where do I go first? Try a new set of 02 sensors? I cleared all the codes and this is what came back. It flashes the CEL at idle.

 

I'm running just about the same codes. All my 02 sensors, plugs, plug wires, coils, and MAF are less then a year old. Mine are most likely due to my new exhaust leaks so I would check there but if it hasn't had the coils done I wouldn't rule that out either.

 

Oh it apparently had the coils done too. But again, off idle, it runs perfect and amazing as far as I can tell. It has loads more power than my 01, as it should. The guy who did the work was shady at best, so I'm sure he could have gotten the wrong o2 sensors or something.
I know it has an exhaust leak, but it is after the cat, so it shouldn't matter.
It initially runs fine for about 30-60 seconds, then starts getting terrible idle, so I assume it's open loop for a minute, then closes the loop and actually starts measuring, and due to a lack of good 02 signal, it runs bad. That's my theory, now I have to figure out why, or I can't register it and pass emissions! It would drive fine right now if I didn't have to worry about that.

 

Well if you have one of them obd2 scanners that would definitely help verify that the 02's aren't picking up a good signal. They're cheap like 10 bucks, get a wifi one if you want to use an iPhone with it. I used OBD Fusion on my iphone, works perfect. As for the exhaust leaks, shove a shop vac up the tailpipe and set it to blow and feel around the manifolds. Free check for small leaks like between the ypipe and manifold. If it's cheap and can rule something out then why not!

 

That's how I got those codes. What else can I do with it on torque? Be specific please.

 

Sorry about that, I'm doing 100 things at once. I am not familiar with torque but you should be able to see live data in regards to the 02 sensors. Not 100% sure about what the readings should be exactly but if it is stuck at .45 or .00 Volts then there is something wrong with the 02 sensor, anything else it is picking up something.

On a side note you should also be able to monitor your coolant temperature with that app so thats a +1 for avoiding head gaskets.

 

With all those trouble codes it could be anything. Got Secondary Air Injection (SAI)? Could be a bad purge valve.
Also, check fuse the 15A F2 in the engine bay to see it is blown.

 

Start up

After about one minute bank 2 s1 drops to zero and bank 2 fuel trim goes way up.

If I hold the throttle open a little bit bank 2 sensor 1 responds and the fuel trim response as well. None of the other three sensors move much at all. They just seem to sit in the middle

Codes right after these graphs

 

I know the sketchy previous owner removed and capped off one side of the secondary air injection. The driver side. He plugged the holes with some bolts. My understanding is that that should not really affect the I really so much and that it is only for the emissions when cold?

 

Well that will toss a bunch of codes
When I monitor my O2 sensors, the 1x1 and 2x1 are constantly changing they other 2 peak and stay steady.

I would say you have a bunch of stuff to sort out, start with secondary and O2 sensors

Then start going over your entire Disco front to back, I think you are going to find a ton of unpleasant surprises.

• Plug wires look ancient
• I would get an inspection camera with light and pull spark plugs and examine your pistons -look for coolant or steam cleaning
• If the pistons are good then you will need to replace the plug wires at the very least as well as the stuff below
• You may need coil packs as well
• Drain and replace the oil in the Diffs and Transfer case
• I would suggest a transmission service
• Engine oil change

If you have water in the cylinders or steam cleaning - you need head gaskets at the minimum. it is not hard to do but given that photo you need to ask yourself what else is messed up.