Try resetting engine adaptations using Service/Test options in the IID tool as well, particularly after the MAF replacement . The engine control module tends to remember the lean codes for a couple hundred miles before averaging fuel delivery back to normal. If you reset adaptation then clear the faut codes it will only take a few miles to see if an attempted fix actually worked.

Lastly, the misfire codes look like a coil issue. How old are your coils? Amazon has the Delphi coils for $33 each right now. That's as cheap as rock auto but with prime shipping. OEM are Denso, but they stopped manufacturing them and Delphi seem to be the closest option.

 

Analysis of fuel trims helps confirm a vacuum leak. Essentially, if the short and long term trim values get closer together (converge) when revved to 2k or so RPM vs. values when idle, you know it's a real vacuum leak. This is because a small leak will not affect the system as much at higher vacuum pressure created at higher RPM (when revved). Like trying to suck more air through a small straw; you'll make more vacuum pressure of you try harder. Same concept. If the trims stay gapped about the same, it's most likely a sensor malfunction. I've had a brand new MAF sensor give faulty readings, particularly when I used a non-Denso/Toyota part on these trucks.

It looks like your pictures are from a GAP IID tool live values. This is exactly what you need, but you gotta read live values for short term trim, long term, left bank, right bank at the same time while revenge the RPM to compare. The IID tool has a graph function that helps... Start the graph with these values selected and go for a drive. If the short and long term trim lines converge (improve) with more RPM, it's definitely a vacuum leak somewhere. It's also possible to have more than one leak, so check these trims after every attempted fix to see if your hard work made any improvement on closing the gap between trims to an acceptable level. Optimal is when the trims track pretty close with the short-term moving first and the long-term catching up after about a second. Sorry, I don't remember LR's threshold for trims, but I remember finding them so they are published.

Check the entire vacuum system, starting with the PCV valve and plastic PCV tube. Inspect the o rings on the inlet of the PCV valve and inside the pipe connections on each side of the the plastic tubes. Check the EGR valve for vacuum lines including the metal EGR return pipe I mentioned before. Check the o ring on the oil fill cap, the brake booster lines, and any other vacuum lines you can trace down. You've got left and right bank lean codes, so it's probably a line on the intake after the MAF that is feeding both sides. A smoke test sometimes don't catch these small leaks and rovers are finicky. But o rings are cheap and parts stores sell them individually if you ask. I try to swap them out any time I can. No need to replace any of these parts unless you see a crack. Replace any o rings that are hard, brittle or flattened like a pancake because these indicate shrinking as the rubber ages. The o ring color indicates the material it's made of, so try and replace each with a matching color (black, orange, grey) so it can hold up to whatever the engineers designed the part to withstand.

Then retest trims and repeat. Good luck

 

Excellent info, thanks!

Today I reset the adaptations after yesterdays smoke test showed me nothing. It was probably my homemade smoke machine that wasn't great at showing a leak so I'll get a real one.

After resetting the adaptations, I took it on a 180 mile ride up to 8,000 feet off-road, and all over hell and yon. Did great, didn't miss a beat and hasnt thrown the codes yet. I'll check all these things you recommended, thank you again.

 

Has there been any resolution to this issue? I’ve been having the same codes for a while now. I even went to the dealer and they updated the ECU. That fixed this issue for a few weeks. Then the light came back on.

The light has also shown “System Too Rich bank 1&2”.

The rich codes have disappeared for now and I’m just getting the 171 code for bank 1.

I’ve replaced the MAF twice. PCV twice. Air intake that connects to throttle body. Cleaned throttle body. Replaced all four O2 sensors. I’ve smoke tested with a home made smoker. I’m getting ready to pull all the fuel injectors and give them a clean. I have a gap tool but am very ignorant to how to read the live values.

Any help would be greatly appreciated.

 

[QUOTE=Coldwater;842410]

The rich codes have disappeared for now and I’m just getting the 171 code for bank 1.

I’ve replaced the MAF twice. PCV twice. /QUOTE]

IF your codes went from both banks to bank 1, it sounds like you had multiple leaks/issues. Intake and EGR usually affect both banks. Hopefully that is resolved, so focus on Bank 1 (I believe this is passenger side on a US vehicle) unless you get other codes.

Personally, I'd check the black plastic PCV tube that connects to the PCV valve. It's the one you pinch to remove. Inspect the entire tube including the o rings inside inside BOTH end of that tube just below where you pinch it. Those o rings keep the vacuum seal and are subject to lots of heat and oil. If the tube is not cracked, just replace the o rings. Use a bit of soapy water to get em off, get em back on, and to re-seat the tube.

You should check the trims using the tips I already posted before and after this. Then reset engine adaptations and check them a third time to measure any improvement. This is the only way to tell if you made a difference.

Read the GAP IID tool manual for live values, Google "short long trim vacuum leak" and watch some videos until you get an idea about what the readings mean. It doesn't have to be Rover specific. Lots of info, you just have to be willing to learn. LR publishes their tolerances for short and long term trim values somewhere. When readings are outside those tolerances, you get the code. If you find them, please do us all a favor and add em to this thread as it seems to be useful to others.

If these steps don't work, hunt down all the vacuum lines connecting to bank 1 and repeat the process above.

 

I have not read everyone's reply yet. Good list you created. I did a video (a bad one) a while back on this. I had gone one step further did smoke tested it. I found leaks, but they weren't the primary culprit.

Here are three other spots that commonly have air leaks. I have my money on your resonator. It has a hairline crack or the rubber connections on them are toast. A smoke test won't generally Identify this because you generally hook your smoke machine up to the hose before the resonator (and that happens to be the spot where they fail). Good luck! You got this....

To save time -
3:00 Minute Mark
5:00 Minute Mark
5:25 Minute Mark





Godspeed. You'll find it.

 

What he said!

 

Thanks all for the quick responses. The resonator has been replaced with a brand new factory unit. I had some cracks and the gaskets were broken. I think I’ll take a look at the hose for the PCV and inspect this and the O-rings further. Can someone confirm if bank 1 is the passenger side of a North American LR3? I’ll try and get some fuel trim recordings soon as well. I did this a few months ago but didn’t really know what I was looking at. I saved the values. I’ll record the next round and see how things look… if someone can help interpret the readings.

 

Watch this video. It is really worthwhile. It helps you understand fuel trim and using it to help troubleshoot. It is really worth the 27 minutes it takes to watch it.

 

Excellent teacher! I first started learning about fuel trim/O2 data about 5 years ago. This teacher really puts it together in a highly useful and instructive way!