Good day fellow Jag owners. After HOURS scouring through the posts and replies on these particular codes and using my judgement as well, I changed the fuel filter on the wife's 2002 X Type with 3.0 and auto transmission. I was getting a horrible stuttering on rapid acceleration and an instantaneous check engine light with the dreaded P0171 and 0174 codes. After filter change the performance is back but my code reader is still throwing "lean" codes. I see the O2 sensor and STFT go to zero when that happens, before filter change. I am thing MAP sensor, since it is showing up on both banks. Any input?
Sparky

 

*thinking MAP

 

Sparky (I'm a Twigget here), I would first say to do a visual of a few parts before diving too much further into the the car. The first hose I would check is the one on the firewall running between the top of the intake and the brake booster. If you look in the middle, you will see a small plastic bulge in the middle of the line. See if the plastic is cracked. If it is, then you need a new "brake booster line".

Next, using a small piece of tubing, put one end near your ear (not into it) and then run the other end near the IMT valve joint (the black covers on the side of the intake facing the tire). Do you hear a vacuum leak? If yes, you need to replace the IMT o-rings.

Next, if you look in the hole between the motor and the intake, you will see a hose running front to back about the diameter of your thumb. It runs from the valve cover to the intake. Remove this hose and look at the underside of it. Is this hose split? If yes, then you need a new "PCV Hose". You may want to consider a new hose if the hose is smooth. It was a noted failure item and has since been redesigned to a new ribbed hose.

The final check I would do is to inspect the flexible boot that attaches the intake to the throttlebody for any rips/tears.

I would also recommend cleaning the MAF Sensor. You remove it by undoing 2 screws on the side of the intake and then removing the sensor. Spray the sensor down with some MAF Sensor Cleaner (do not spray directly down the MAF sensor, but instead bounce the spray off the interior side of the sensor). Shake out the extra fluid and then reinstall.

That should fix your issue.

 

Hey Thermo, have checked most of the vacuum items, I'm thinking MAF sensor as well. I'm also going to tackle the dreaded transfer case oil change this weekend! Wish me luck!

 

Spark, it isn't as bad as people make it out to be. Yes, there is not a lot of room. But, I found that using a radiator drain plug with a 1/4x1/2" NPT adapter makes things pretty easy. Just have to make sure you get the valve with the collar on it else you don't have a place to attach the hose to for filling.