hey guys new to the forum and looking for some assistence.

after hours of countless searching on google and every land rover forum i could find landed me to ask for some help from this forum as i see the knowledge pool here is fairly large . Im working on an 05 LR3 with a 4.4l v8, it has intermittent codes p0171&p0174 for system to lean.

heres the scenerio: after performing a tune up the codes came about, cleaning the throttle body and smoke testing the intake came up with nothing and fuel pressure is 60-65 psi. when driving on the interstate the long term fuel trim runs 0.78-3.17%, if my knowledge is correct it should run no greater then 2-3%, well upon deceleration the fuel trim will skyrocket to 10-13% and the check engine light will illuminate and the codes will be there.

the spark plugs have been changed, the battery was replaced and the MAF sensor has been replaced as well.

the other symptom related or not dont really kno is that when the MAF was replaced the engine idled around 1100 rpm instead of 750-815 rpm.

like i said ive been pulling my hair out with searching and any help is greatly appreciated.

thankss

 

Here is a link where you can put in your fault codes and get a result.

Diesel performance tuning and economy remap chip tuning for Landrover Defender Discovery TD5 Puma TDV6 TDV8

p0171 System to lean bank 1
p0174 System to lean bank 2

You will have to wait for someone who knows more than me. There are several LR mechanics on lrrforums as well.

 

I am having the same intermittent codes. I have completed most of the same repairs as you. Did you ever find a fix for yours?

 

these codes, on this truck, can be many different things. Fuel pressure, intake leaks, incomplete ignition, MAFS, exhaust leak, and also engine calibration file.
In order to know where to start, and not just throw parts at it, you need to know what the adaptive fuel trims are, which most scanners, even autologic, can't tell you.
That said, it is usually MAFS or just in need of a major tune up.

 

Thank you Dave for your reply. I have 72,000 miles on it. I bought it with 69,000 and no service records. I have cleaned the throttle body and MAF, Cleaned and re oiled the K&N, Changed Front and Rear diff fluids, Changed Tcase fluid, Drain and refill on the tranny, Coolant flush and refill. I am fairly comfortable working on it but just didn't know where to go. I was going to try spark plugs next. I guess I may need to take it to the stealer for proper diagnosis. Have you seen damage from prolonged running with these codes? Have no idea how long they were on before I bought it.

 

I have seen anecdotal posts of over oiled K&N filters upsetting the MAF sensor. Personally I don't see that they give you any benefit for performance on a 6000lb truck so I'm happy with the regular old paper....

 

worst case is bad (worse) gas mileage... do the spark plugs, along with a new PCV valve, i always recommend replacing the ignition capacitor at the same time, they dont fail that often, but good assurance for the price(~$25)
If you end up going to the dealer for diag, ask them to print you a copy of the "Adaptive Fuel Trims" before they do any repairs, or reset anything.
I run a K&N on my car, not for performance gains, only due to it being an oiled filter, which is better at keeping moisture out then a paper filter. But if they're over oiled, it can deffinitly mess with the MAFS.

---Might want to get the adaptive before you do the tune up, or drive it for a good 100 miles(use the whole rev band along with normal driving) before you have them print it, if the light returns.

 

I cleared my codes drove the vehicle till the light came back one and kept driving it took about two weeks the light went off the engine ran great, I'm thinking the computer couldn't read that new MAF correctly and had to relearn it not sure but that's all I did

 

If you need anymore info ill be more than happy to help

 

It does take time for it to relearn the adaptions after a repair if theyre not reset, and can turn the light back on just for them not being fully adjusted back. Hopefully you're ok now.