All,

You guys are AMAZING. I just got caught up on the thread after working 10 of the last 14 days.

To someone's previous question - no, there's been no resolution yet. After that long trip with the adaptations rest the light came back on.

Today I replaced the TB gasket. The one I took out was basically flattened after being in there so long. I also go the only bolt I could reach at the back of the engine to the ERG to tighten a bit. That was enlightening indeed!!!

Going to reset adaptations and run some live values again and then post them and reread the thread and watch the video above to learn more. Never stop learning.

I was also thinking about getting a new RRS pipe to remove the resonator like someone did. Maybe it's worth a try.

Off to reset values and go for a drive. I'll letcha know.

 

That was an exceptional video! I'm amped to apply the knowledge now.

 

Here are some more IID Tool logs. After watching the fuel trim video, I think I get it. It was most pronounced this morning when it was cold. 29 degrees outside. Started cold in the garage and then about a block from home I remembered to plug it in and record. Also had a rough idle at the stop light and stop sign then it went away when it got hot.

I included the following logs:

1. Reset Adaptive Values: replaced the TB gasket then went for a drive
2. 2nd Drive after Values Reset
3. 5-min idle after driving around all day
4. This mornings almost cold start and drive

One of them has the O2 sensor data but I don't remember which.

Today I'll try spraying around with some cleaner and looking for what gets sucked in starting on Bank 1 since that may be the side if I'm reading the logs right. Not sure if I am tho so help is appreciated!

 

If I’m understanding this video and the difference between LTFT, STFT and the O2 sensors… #1 the sensors need to be hot and at operating temp to be functional and are less important to determining the issues as compared to STFT and LTFT. #2, If LTFT rise significantly with rise of RPM there is a fuel delivery issue or MAF issue. #3, If STFT rises and LTFT stays at around zero, then you have a vacuum leak.

This all being recorded at operating temps and not starting temps. I just replaced all four of my O2 sensors thinking they are the problem. Now I’m learning I’m the guy that just buys new parts and doesn’t actually know what I’m doing.

I’ve attached a graph of my STFT, LTFT and RPM’s while city driving at operating temps. Who can tell me what’s wrong?!? Vacuum leak or fuel delivery issue????

 

I have a new GAP graph that was recorded while the Check Engine Light was triggered today. Can anyone help me read these? I’m so confused. I’ve watched the video s couple times now but I still have no idea if I have a vacuum leak or fuel issue. I also now have a 171 and 174 code so both banks are lean. I’m leaning towards an air leak.

 

It's kind of hard to tell on my mobile from that graph, but what I think I see is that your ST fuel trims go up when engine speed is at idle, right? To me, that points to an air leak, as they tend to be more of an issue at lower engine speeds.

But it doesn't rule out the possibility of there being insufficient fuel at idle either, from say, injectors that are lazy/clogged at idle but freeing up at higher speeds or compensated enough by other cylinders pushing extra fuel at speed. Did you ever get your injectors cleaned etc? Replacing my injectors with a reconditioned set is what finally fixed a persistent but intermittent lean condition on both banks that I was troubleshooting a couple years ago.

I'd check again for all possible air leak sources first. After that, I'd work on the injectors and seals.

 

I started removing and cleaning my injectors today. I also caused myself a ton more work. When removing my injectors a couple parts from them dropped into the engine. New issues now. I need some new injectors and I need to get the parts out of the engine. When the car is at idle or the RPMs drop the fuel trim looks odd to me. A couple of the injectors I have cleaned have been incredibly clogged. I think these are the original injectors with 160k on them. Hopefully when I get new injectors installed and button everything back together the codes will be gone for good. Fingers crossed but I’m not holding my breath. I’ll let you all know.

 

I am still getting those the 171 & 174 codes on my truck. I was able to get a wavier for my emissions test so I was able to register the vehicle (whew). My next steps are to replace the seals on the injectors and check the bolts on the egr pipe. The pressure is off now (with failing emissions for registration), so as time allows :-)

 

So my light turned itself off for a while and has decided to come back after replacing the MAF and resetting adaptation values. This time I only get lean bank 1 codes which is weird. I also noticed the top EGR bolt being very loose (as posted in this thread: https://landroverforums.com/forum/lr...stions-114403/) which I've now tightened. I found that after replacing the EGR to TB gasket today.

I'm going to reset values again and run it and letcha know. So far no codes.

Would the loose bolt on the top cause the lean codes?

 

I am in the proses of cleaning my intake manifold and fuel injectors. I took my injectors to a local shop to be fully cleaned and serviced. The local shop gave me an update today for the injectors. Said their spray pattern is nominal and injectors are functioning well… especially for their age and mileage. Original injectors with around 160k on them. This is not my problem causing the 171/174 code. I need to dive deeper into a vacuum leak. I’ve ordered some new vacuum hoses via Atlantic British. New gaskets for the intake and EGR. I’m definitely doing 1000 times more work to diagnose this problem because I don’t know what I’m looking for now and don’t where to find the problem anymore. I’ve taken the Rover to a LR dealership and two other mechanics. None could find or diagnose the code. I’m sick too my stomach with this stupid code. Where is the vacuum leak coming from??