I am getting the running rich codes (P0172, P0175) . Trying to track it down. Some background

-Around a year ago I had the throttle body rebuilt by A.S.I.
-I have replaced the air filter
-Cleaned the sensor connections
-Had a busted O2 sensor but recently replaced it

When I was cleaning the sensors I noticed a puddle of oil in the TB, could this be a clue?

 

I worked on a XJR that was running rich, could not figure it out. It was the MAFS.

 

Check the PCV. From the camcovers there's 2 breather pipes (full load - RHS into Air Tunnel /part load - LHS to throttle body). If either are "really" wet with oil, there may be a problem with the camcover's inbuilt oil filters. It's a plate with steel wool behind. See pic below.

 

Thanks, I am going to clean the MAFS see if that helps. I may purchase a new MAFS, the OEM wich is DENSO but you can get a quality Delphi for $45 (also no names are around $15). I usually like to stick with OEM but what a price difference. Anyone have experience with Delphi.

I will take the look at PCV

 

Stick with Denso. Far too many issues reported over the years with non-Denso sensors in these cars. You will find reasonably-priced Denso sensors searching amazon.com....

 

I fixed my 2001 XJ8 P0172, P0175 with a new MAFS from RockAuto after trying 3 or 4 good used from other running cars but I ended up trying the new one and it fixed it.
I bought the Walker for about $30.

bob

 

Might also check for blockage in the Partial Breather port.
https://www.jaguarforums.com/forum/a...ings600-03.pdf

 

Normal to find oil collected in the low areas of the intake ever since the epa mandated that crankcase vapors could not be vented to the atmoshere and had to be totally sealed instead of just a pcv and had to be run through the intake to be burned in the combustion chambers. Only way to stop in is to install a catch can. One of the reason people misdiagnose a lean engine since the crankcase now becomes a source of vacuum leaks from old poor sealing gaskets.

 

Following Bob's lead, I bought a Walker 245-1095 on ebay for $16. Works great. I'll carry it as a spare for my 06 XK8. LTFT bank 1 was 9+ with original, is 6+ with the Walker.