Forum Members, Land Rover Enthusiast, and Friends,

HELP. Lean on both banks and I'm just sucking at life over here.

2006 Land Rover LR3. 4.4 engine. I’ve got 232k on it and I’ve had it since it had 29k on her. She runs just fine which is what is so annoying. I just have lean codes on both banks that won’t go away and throwing parts at it has not been a successful strategy.Thus far - I’ve replaced the EGR valve because it showed a leak during a smoke test. (was so happy. Surely this was the issue! Nope)

• replaced EGR gaskets (Cause it was still smoking, Surely this was the issue! Nope)
  
• replaced throttle body gaskets. (Cause some dude said they're super finicky - Surely this was the issue! Nope)
  
• replaced MAF sensor twice - once at the very beginning of the process and then again three or four weeks ago when my local shop said that was the issue and replaced it with a genuine part. Surely this was the issue. He was SO DAMN CONFIDENT! 10 Miles from the shop (Twice the normal range), the CEL returns for lean codes. Nope!
  
• have done fuel injector service - Cause why not?
  
• have done plugs (just cause)
  
• have replaced PCV valve.
  
• have smoke tested at every change to ensure it wasn’t something stupid like an air intake plenum lose or something (which it was. But my excitement was short lived when the lean codes returned).
  

I am attaching two links. One is to the freeze frame data. The other is to the data streams at idle. Idk what value either sets of data have - but I'm confident one of you actually understand these metrics - and hopefully you'll sniff out a cause and maybe give me THEE clue that helps me fix this.

I am 5 months late on my inspection. I got a ticket for it last month. $150.00 - My friend suggested not to worry about it and consider it part of Rover Maintenance. He had a good point......

https://imgur.com/gallery/uf2VKnw

https://imgur.com/gallery/wCluok8

 

Fuel pump? Low fuel pressure can still run vehicle. I went through this with my D2 and it was fuel pump.....it had like 20psi and would run and drive.

 

It seems that most of what you’ve done has been to look for extra air entering the system, which, fair enough, is more likely. However, along the same vein as this suggestion, have you ever changed the fuel filter? Any chance it’s clogged?

 

Have you performed a throttle body adaptation reset? To zero back to baseline with all these new parts? Then let the truck relearn the new item functions?

 

The O2 sensors will also put the MIL light on and show up as lean or rich. Even though yours look like you would expect

 

Good comments. You all came from different angles and that's good for the mind.

Few thoughts.

• Fuel Filter????? I didn't think the LR3 4.4 had a fuel filter. If it does - I am going to feel like an idiot (Unless we're talking about the in-tank "filter")
• Fuel - While we're on it... I went and got a HF fuel pressure tester. In a turn of events, and according to my research, it appears I have TOO much fuel pressure?!?!?
  • See Video link - First part is upon start up and you can see the gauge is NOT happy. Then it leveled off right around 80 PSI which seems high - I was told 65 was the number, but I'm not experienced enough to know margin of eror.
• At Douglastic - Well... not sure what you mean. I did hard re-set the thingy using the battery method (disconnect battery - jump them together, wait ten minutes, and hope your rover is new-method). How confident are you that this is a programming issue? Like - confident enough for me to Drop $500 on a tool that can actually perform this function?

 

Apologies, but you're right. No fuel filter (unless it's built into the pump). I remembered replacing ours (which was a real bugger to get the connectors off of, though easy to access), but I just realized it was on our L322 Range Rover, not the LR3. Sorry!

And by the way, if it makes you feel any better, I was in a similar situation recently. I had a "loose or missing fuel cap" error message and couldn't pass emissions. So... I replaced the fuel cap. Message went away, but came back a couple hundred miles later. Did some research online and discovered the most likely cause was the DMTL pump. Replaced that with a new one, which was a huge pain in the a$$. As you say, "surely that must be the issue!". Test drove and no error message. However, after enough drive cycles, the message did come back. Finally took it into an indy shop and asked for a smoke test. They told me that brake booster hose had become disconnected for some reason, but that they were seeing smoke from around that area. They reconnected the hose and told me that if error came back, I should replace purge valve. Test drove car and error message came back. Replaced purge valve (to the tune of $400 for the part!!!). Went out to do drive cycles. Error message didn't come back. "Surely this must be the problem!!!" Went to take care to get emissions test. While waiting in line, turned car off. When it was my turn, I turned it back on and boom; error message came back. @#$&#$@# Finally conceded and took to LR dealer. Took 6 days for them to even look at the problem, but came back and said fuel flange needed to be replaced to the tune of a small fortune. Fine. Did it, did drive cycles. No error message. Took it to emissions inspection station and the guy who tested it came out and told me it hadn't passed. I was about to cry until I saw his face and realized he was joking! Grrrrrr. Anyhow, truck is finally road legal again, 2 months after registration expired. :/

 

You were getting lean codes for this "fuel flange"?

 

No. The only error code that was stored was "small evaporative emissions leak". I can't remember what "small" equates to, but something like a hole size 0.5mm to 1mm in diameter. No lean condition, but wanted to share the misery of trying to track down a difficult and irritating problem.

 

FYI, your readings do seem to show something funky going on. Shouldn't long term fuel trims be close to zero? Having them at 22-23% shows that the car is adding fuel to try to compensate for an overly lean condition, correct? Perhaps somebody who's more knowledgeable than me could chime in here...