list of problems!

[dirtyrice]

First off I have A 2002 4.0 xlt. My check engine has came and it has begin to ping under load and idle slightly rough. The code says system too lean. I have replaced the plugs and cleaned the MAF and still no change any suggestions would be very helpful. one note to add is it has 77k miles

 

[Bruce]

Possibly bad 02 sensor, plugged fuel filter, just a few.

 

[superranger4.0]

If you are getting codes p0171 p0174 lean banks 1 and 2 i would start checking for vaccum leaks and if no leaks are found replace the mass air sensor. good luck

 

[Big Jim M]

Yep! Too lean has nothing to do with the plugs.. Either a module is telling the computer to lean out the mixture too much..or you have a vac leak.. or there isn't enough fuel getting in the cylinders.
Big JIm

 

[shadetree]

I have replaced the plugs and cleaned the MAF

How did you clean the MAF? Just squirting it with some type of cleaner doesn't always clean the elements. Like any thing that heats and has oil applied, it will become "crusty" after a while. You have to gently break the crust off the element with a small brush and solvent, or equivelent. Look at the element with a magnifying glass. If it is black, its contminated, if it's nice and shiny, it is clean. I use denatured alcohol.

This symptom is sometimes cured by something a simple as changing the fuel filter. Weak pump will also give this symptom. Is it noisy? A fuel pressure check will give you an idication of the fuel system if you have the means of checking. shady

 

[dirtyrice]

I appreciate the suggestions,I am going to change the fuel filter tom. It cant hurt and a fairly inexpensive part at that