2000 XJR 65K miles
Checked as a result of check engine light and performance restricted message.
here are the codes that showed up

P0171
P0174
P1111

I cleared them all,
then under acceleration the P0171 came back. The scanner shows it as bank 1 lean.
I do feel under mild acceleration, it slightly stumbling a tiny bit........

Ideas?
Thank you all for your help.

 

right side bank (1) may have avacuum leakat air intake after mass air flow sensor..you can smoke test the intake or here for a leakor it may simplyneed a MAF sensor

 

Thank you JG.
I will check it out.

 

JG I just checked the air intake from MAS to throttle body, smoke and noise indicate no
obvious leakes. But I did notice a bit of oil in the air intake tube, no doubt from the PCV fitting......is the oil in the air intake normal?
Also the air intake tube does not seem to be real tight where it goes on top of the throttle body....is there supposed to be a clamp on it there?

Could that be the culpret?

 

That could cause lean codes. I have also seen several intake tubes cracked at bottom cause it.
I would look at fuel trims while accelerating. If -20% put a mass air flow in it.

 

Will do,
I pulled the tube and checked it very well, no apperent cracks anywhere.
I am leaning towards the MAS.
Thanks!

 

Would that also explain the stumbling at around 3000 RPS....but clears out when I get on the throttle hard and pass 3000 rpms?

 

It can, hard to say without being there. Look at fuel trims though.

 

Fuel trims while running are all in the +0 to +25 Unless I am off the throttle completely when coasting up to a light.
Then SOMETIMES they drop to as much as -30 but very rarly......what is the correct procedure for checking the Fuel Trim on the scanner?

MAF also seems good on the scanner. It goes way up and down directly realted to the engine speed.
Whats the next step? Throttle body clean or change out completely?
I really want to get this car running puuuuurfectly.

 

Are you talking %?
Sit at idle and see what the trims are.
Then put handbrake on, put car in drive and keeping foot on brake, bring RPM up to about 1200 or so. Dont let car move. See what they are. Then drive under light acceleration and see initially what it reads.

 

Yes sir, that is in %
I will do that tomorrow and post the results.
I truly appreciate all of your help!

 

Problem fixed! A new MAF sensor did the trick!!
Thank you all for your help!!

 

quite common fault
congrats on the fix

 

good job!!