Restricted Performance - Fault Codes resulting in read out Banks 1 and 2 running lean. Specialists have re-tightened EGR valve and further specialist now suggesting Oxygen Sensor. Any suggestions ?

 

Smoke test. Do a smoke test and find out all the air leaks. Locate the fuel pressure regulator and inject smoke through the vacuum line directly in the throttle body. This allows you to test with all the main culprits in place. There are so many places where air can leak in that is it not generally worth looking one by one. And yes, all these leaks are cumulative, these lean codes can definitely have more than one cause. Once you fix the leaks and the codes go away, you need to monitor your fuel trims with a cheap OBDII adapter. Codes trip at 25% fuel adjustment, but you really need to be around 5% or less to restore proper jaguarness in the feel of the engine. O2 sensors are heavily monitored by the ECU, so unless you have specific codes pointing to them, let these sensors be for now. FWIW, some years use a very common air flow meter that might be worth changing just because. And you can clean it with a dedicated spray, but it rarely "fixes" it.

PS: Be sure to update your settings to show your car model and year so folks can help you better.
PPS: If you are dying to check stuff out, start by taking the intake tube off and double check it for cracks, especially around the accordion part, top AND bottom.
PPPS: If the specialist was already suspicious towards the EGR, the EGR pipe is known for cracks, you guessed it, around the accordion part again.

Best of luck, keep us posted.

 

If both banks are running lean, it’s unlikely both O2 sensors went bad at the same time.

So +1 to Fmertz, probably a gross air leak after the MAF, ie the accordion section of the air tunnel, or maybe a bad MAF sensor. Worth DIY check on both of these before going down the O2 sensor replacement route.

 

The smoke test was done and resulted in the EGR bolts being tightened where there was a leak but fault returned as soon as the SC used. I think from all posts that it’s definitely not the O2 but another leak or combination of leaks. The search will commence! Thanks all David and Fmertz.

 

There are seals on the superchargers that are known for leaks. There is an original part, and a later design. The seal is apparently sandwiched somehow, and can slip out of place. XKR folks are well aware of this. Other option is that the torque of the engine under load opens live cracks that do not show with a smoke test. Take the intake elbow out and double check it, including the resonators.

Other cheap option is to clean the air flow meter in case it is giving out bad readings at higher air flow.

You'd be well served with being able to read live OBDII data, especially the fuel trims. A cheap ELM327 with a phone app does just fine. Focus on the 2 banks long term trims and see how they evolve with rpm and load. They should ideally be zero everywhere (the base fuel map is perfect), but anything below, say, 5% is great. Codes come up at 25%.