I have a 2006 LR3, 4.4 V8 that started to throw check engine light, error P0171 and P0174,
Running lean on both bank 1 and 2.
I did some searching on the forum and it seems like a pretty common issue, but I have not found anyone who claims to have solved this issue.

So fare, I have replaced the
-Mass Air flow sensor. (Desno)
-Oxygen sensors, all four of them
-Crank case vent Valve
-Resealed the gasket on EGR valve and Throttle valve with gasket maker.
(I had installed a new EGR valve which was horrific. 7 out of my cylinders were misfiring, it was a Denso brand EGR valve, but I think the product was defective, I returned the EGR valve and reinstalled the old EGR valve)

The is still on, and I was wondering if any of you had fixed this issue..

One observation: if I reset the error code, check engine light will not comeback until I turn of the engine, restart the car and drive a few miles

 

Have you cleaned the throttle body? Did you very closely inspect the intake plastics? Common cause of that fault.

https://landroverforums.com/forum/lr...sonator-91604/

Also with the EGR, make sure the bolts to the tube way in the back are tight. Make sure the oil fill tube cap is sealing good and the dip stick o-ring at the top is good.

 

Yes , I did clean the throttle body while resealing it. It was rather clean to my surprise.
intake plastic looks to be crack free, though I did realize that the bolts screwing down the air box cover and mass airflow sensor was spinning loose.
I was thinking that the air-box cover would not be an issue as long as the air filter below it is seated correctly into the lower air box housing…
However, the mass air flow sensor is not secured tightly onto the intake hose due to the loose screws.

 

Any prop selling before the MAF sensor is of no worry for the engine as that air has not been metered yet. The MAF has an o-ring, so make sure its secure but I suppose with that o-ring it does not have to be highly, just has to seal.

 

Although the mass airflow sensor is not tightly secured onto the intake hose, I don’t think it will come loose due to regular engine road vibration due to the O ring,
but I will check to see if there is an air leak around the MAF sensor.

 

Yeah, you are prob okay.

You may want to consider looking at the exhaust manifolds. In theory, if they are not seated properly they can cause lean codes. I never quite understood how since they are, essentially, under output pressure from the engine. But I think its a bit of a Venturi effect. Maybe keep this in the back of your head as a possibility since the 4.4 exhaust manifolds are notorious for loosening. Mine certainly were.

 

Do you have a GAP tool to reset engine adaptations?

 

I fought the running lean CEL for about a year, doing everything you listed plus having a LR dealer do a fuel injector cleaning service. Nothing worked. I also noted that the MAF screw hole downstream of the MAF sensor was stripped. I filled that with JB Weld and assumed that would seal it. I was still getting the CELs and when I checked my JB Weld repair I found that it had popped out. I bought a used airbox on ebay, installed it and have not had a CEL since (over 2 years).

 

No, l don’t. Only thing I was able to do is to undo the negative battery terminal for few hours.

 

I did try filling in the stripped screw hole with some instant glue, but that did not do anything. I might tie down the Mass air flow sensor with duck tape to see if that changes anything before buying a new intake hose/ air box.