I keep getting code bank 1 is lean. I checked vacuum lines all looks good , ran long fuel trim bank 1 is 19.56 bank 2 is 4.6 at idel. Ive cleaned maf sensor. Checked air box no leaks. I dont know what else to do. It acts likes0 its running great then all of a sudden goes into restricted preformance and runs like crap. I reset and runs great again. Any ideas would help

 

It could be an intake manifold gasket or a bad O2 sensor on bank 1 that could cause inaccurate readings and throw a lean code.

 

That was my thought im doing that in the morning, 1st see if any intake bolts are loose than spray at base of intake to see if trims change. I guess if nothing there check brake booster.

 

Welcome to the forum.

Are you getting code P0171? I ask because some scanners and code readers have generic fault descriptions that are not always accurate. For best results, use the 5 digit code and look up the official Jaguar description here:

JagRepair.com - Jaguar Repair Information Resource

Scroll down to your code (P0171?) and note the list of possible causes:

Engine misfire
Air intake leak between MAF Sensor and cylinder head
Fuel filter / system restriction
Fuel injector restriction
IP Sensor fault (low fuel pressure)
Low fuel pump output
HO2 Sensor(s) (1/1, 1/2) harness wiring condition fault
EFT Sensor fault (low fuel temperature)
MAF Sensor fault (low intake air flow)
Exhaust leak (before catalyst)
ECM receiving incorrect signal from one or more of the following components:
ECT Sensor, MAF Sensor, IAT Sensor, IP Sensor, EFT Sensor, TP Sensor


Here's a good primer on using fuel trims when searching for vacuum leaks. For comparison, what is the other bank reporting?:

JagRepair.com - Jaguar Repair Information Resource


2003+ V6 models are prone to damage on the bottom of the resonator on the intake duct. This typically causes a lean condition on both banks, but it is very quick to inspect once you know where to look. See post #32 here:

https://www.jaguarforums.com/forum/s...2/#post1934812