Hi all. Just to introduce myself. Recently bought a 2005 rrs 4.2 supercharged. Have replaced timing chains as they were rattly. Still haven't managed to get it to run properly so will probably be asking for help very soon. can't seem to get rid of lean bank 1 code. Have fun.

Check out user Lrstaylor posts, do a search for them.....he had a similar problem to you 2006 L320 4.2 Supercharged
2009 BMW X5 M-Sport - Gone
2007 L320 2.7TDV6 SE Buckingham Blue - Gone
2011 Jaguar XFS 3.0V6 Diesel - Gone
2009 (59) L320 Facelift 3.0TDV6 HSE White Wrap - Gone
2008 BMW X5 M-Sport - Gone
2005 Audi A6 3.2V6 Quattro S-Line - Gone

had running lean on bank one and two found I had slight blow from manifold gasket and changed the lamba sensors

Thanks i will check out his thread. Have ruled out vacuum leaks and when I check on my scanner the lambda sensors on both sides read the same but feel trims are +19% on bank 1 -3% on bank 2 so something fishy going on. It failed MoT after the rebuild with high CO but have fixed vacuum leaks since then.

Hi All. Wonder if I could please pick the forums brain to decipher readings taken from my RRS 4.2. Problem as stated above. When looking at the data on the O2 sensors bank 1 states closed loop control off bank 2 closed loop control on. Sensor 2 bank 1 have a voltage of 1.78 constant and the associated fuel trim was 0 percent, then after a period of time dropped to 0.1v and pushed the asociated fuel trim into a negative number. Sensor 2 bank 2 showed between .6 and .8 dependant on revs/ throttle with an associated fuel trim in the 1 - 3 % range. Am I right in thinking this sounds like sensor 2 bank 1 has a bad connection or is busted / gummed up? Thanks in advance for your help

kevinjrob72
just a quick question has your 4.2 been fitted with LPG? as this might have something to do with your readings

Nope no lpg just good old petrol. Work completed so far (as it probably something I did:)
New timing chains, strip down and clean inlet system, supercharger snout rebuilt, injectors cleaned and new seals fitted. Smoke test for vacuum leaks shows no leaks. Leak down and compression on all cylinders passed. New spark plugs, oil and filters.

Just getting really skewed readings between banks for fuel trim. No engine light but fault codes in the background read lean bank 1.

Oh and when it failed MoT on emissions it had high co but hydrocarbons and lambda were fine. But since then I have fixed a couple of vacuum leaks.

you might of cured it like I posted I changed all 4 lamba sensor
it could even be the maf sensor as that can interfere with the air readings