Hi
05 XJR
New fuel injectors, new coils, new spark plugs, new oxygen sensors, new PCV, new fuel rail pressure sensor, two used water temperature sensors and two used MAF from normal working XJ8.

What else could causing p0172, P0175?

The symptoms is it would be bank2 rich first and then bank1 going rich, too. And then the Check Engine Light on.
Cold start is perfect but hard to start when the engine was warm up.
Few days ago, I found out all of the bank2 spark plugs are better than bank1 after 23000km, it seems my bank2 has problem.
Any ideas?

 

I my self would look for a air leak as its getting irregular readings

 

The xj8 and xjr maf is not the same. So I`m guessing that this is your problem

 

Not likely an air leak - you'd expect LEAN codes.

Could be the wrong MAF.

Maybe blocked cat(s).

 

wrong maf

you need denso 197-6040

 

Thanks guys,
now I contact the local shop to test is there any air leaking and order a brand new MAF.
Hope it will solve my problem, felt bad when I see the Check Engine Light every day.
But if the wrong Maf would cause only bank2 running rich first?

 

Is cat mean catalyst?
I had check the technical manuals, it seems the SC catalysts are the same as V6, but I’m not sure.

 

can you points out which one is correct for supercharged engine?

This is from another 4.2NA

This one is on my XJR now. The original one is gone since I replaced few weeks ago.

 

both wrong.

order 197-6040

sometimes sold as a subaru maf

 

thanks
I ordered the correct MAF and solved the system too rich, but I still got hard to start problem when the engine is warm up.
sometimes get unstable idle.
I did test air leaking, it seems fine.

 

check fuel pressure

 

yes the fuel pressure sensor is new but I will check it again.