XC90 Lean Bank 1&2 Issues

[chitownV]

You have to slow down and take a step back. Please listen to sound advice because it seems like you listen, but do something else.

First, you are supposed to give it more time for the LTFT and don’t clear the codes as that will clear the LTFT, except clear the codes for each time you switch the MAF or remove it. One of the things to tell if it’s ready is if you are emissions ready after clearing the codes. The cat should be one of the last components to be ready, and then you know you have enough drive time for the LTFT.

Why do you think it takes time and drive cycles to get the cat ready?…it’s not because the O2 sensors or catalytic are not ready or functioning. One main reason is to ensure the engine has enough time to adjust the LTFT so the O2 sensor readings are accurately representing the condition of the engine and catalytic converters. Getting it emissions ready is how long you should spend. All that work you reported unfortunately is not accurate. That’s not marketing A/B testing.

When you disconnect the MAF sensor, you are setting a default mode, hopefully for the MAP sensor to be used instead, and it should happen quickly. It is one method that might yield a result. This is not the same as disconnecting the VVT or Camshaft Profile Switching (CPS) solenoids, or disconnecting the intake runner flaps. Those don’t have other sensors to cover…these are active. Not sure what you were trying to get there.

Instead of jumping into more random parts attempts, could you enlighten us of what you did before and the history?
- Did you ever clean the MAF?
- Why did you change the MAF when you had trouble starting…how did you come to that decision?
- Did you ever unscrew the MAF and ensure it is not leaking air?
- Did you ever have the intake, manifold, or any other parts disassembled?
- Did you have any other history of codes, or other running issues?
- Did you clean/rebuild your injectors yourself?

What are you doing about the PCV? You do know that a bad or failing PCV does not have to cause a whistle in the 3.2 and one way to know is to look at the oil being dumped onto the spark plugs, particularly bank 2 and/or cyl #6, the bank of cylinders you originally had the misfire codes.

Look at this thread about the no-whistle PCV issue dumping oil. See how the #6 plug looks like all of yours: https://www.swedespeed.com/threads/need ... rs.612237/

This is one of the 3.2 resource links I added in this 3.2 post. The recommendations in that thread are there for a reason and the brand of parts are there for a reason: https://www.swedespeed.com/threads/the- ... st-7332383

You have to also remember that a smoke machine might not reveal a leak as there is more vacuum when the engine is on. Parts can flex. We see this a lot with turbo cars when tracking down a boost leak. A smoke machine has its limits.

Again, instead of buying more different things, spending more time trying random things, buying more unknown parts, you need to slow down and have a sound baseline. Get the good main parts that are known to work correctly. Then reassess. You could have installed new bad parts and it’s affecting a correct diagnosis.

[Hofstad]

I understand your concerns and comments.

I my defense, the car was hot (drove to a further Shell gas station to get good fuel based on your recommendation) while I was doing this. Even drove the car around after swapping to the old MAF.
- Reset all DTC and engine adaptations before looking at LTFT. All STFT and LTFT values go to 0% after resetting.
- After a few seconds of idle I get a lean code on both banks and a check engine light. I can’t image from the factory it is that way as well where there is a check engine light until the cat’s are warm.

All that is valid unless the LTFT is still memorized even though it says 0% after resetting.

Again, I will buy new spark plugs, but would a bad spark cause a lean engine?

I changed MAF previously because I took it out and it looked dirty. Did not clean it and went for a new one. Removing the intake is a bit difficult and requires more parts (seals etc.) Was hoping to proof it is fine with the smoke test.

I agree with quality parts, especially with sensors but I am unsure about PCV unit. I had a better look at it yesterday evening and it’s really nothing more than a spring and membrane. Maybe there is another way to test it than the glove test? Want to avoid spending another $200 on a part that was fine in the beginning already.

In your first linked thread the issue was not resolved and the PCV valve was fine, right?

[chitownV]

One trap people get into is “justifying” this or that. You have to get a proper diagnosis, even after the code pops up. That means, to know what is working first, then look at what is not working. There is no defense when it comes to this because you are only hurting yourself if you want to justify why not to do proper diagnosing and don’t know how/why these systems operate.

Everyone knows there is a process and requirements to meet the emissions readiness, which includes highway driving for certain amount of time, etc. Sometimes it can take a couple days of normal driving because there needs to be a number of cold starts as well.

What we covered
We went over very well known parts to cause issues, including where cheaper parts still caused problems. Went over the air/vacuum management, fuel, and spark. Unfortunately, hiding info doesn’t help, even if that means you are on a budget and can’t afford a PCV right now, so what to do until you can…which is fine. Perhaps we can help as we understand people have their own lives & reasons.

You still didn’t mention if you cleaned/rebuilt the injectors and if so, how? Or if you bought a new set, and from where.

PCV issues
You popped open the cheap PCV cap and diaphragm yet don’t know what you are looking for. You have not researched that even the Dorman cap & diaphragm leaks because of poor fitment, still causing issues. I would not suggest to pop the cap on the good OEM FoMoCo PCV (that pgill mentioned) as you can bend or break the plastic cap at the very least. I linked that part from FCP earlier.

Your spark plugs look like you still have a PCV issue. The PCV can still cause running, lean, and/or rich issues, for both banks from the very start. Not sure why you went very cheap on this part that is very well known to cause issues at even 100k miles on any engine using a diaphragm PCV/CCV.

MAF issues and improper readings
You removed the MAF and said it was dirty, which means you probably cleaned it. There is no defense here, if you are asking for experienced & trained help to fix your 3.2, then let us know if you cleaned it. It’s very relevant. The fuel tables do rely on proper MAF readings. If this is off, it’s like measuring in metric versus standard, they both measure and will give you distance, but it will be off from the very start.

Even changing to a different brand, Delphi instead of factory used Denso, could be off. Not sure why you chose to use a different brand. Like I mentioned earlier, it’s understandable if there was difficulty, like how FCP doesn’t list the Denso MAF under a 2008 XC90 3.2, but searching via part number shows they have it.

Why is your MAF dirty?
My next question would be why was it so dirty? Did you use a K&N filter or other oil based filter which can be known to ruin MAFs due to the oil? I have similar mileage and replace my paper air filters regularly with FCP’s free lifetime replacement warranty and I don’t have a dirty MAF causing issues.

Just an FYI, the glove test does not work for the 3.2.

Hey, it’s your vehicle. Hopefully, you can take it from here and figure out your issues with your methods. There is a limitation to internet/desktop diagnosis.

Keep us updated if you figure it out. It may help others in the future.

Cheers and good luck.

[Hofstad]

Got it, trying my best to solve these issues. I understand we need to validate the baseline before trying to mark off issues.
- PCV
If the new one could be leaky and have bad fitment, why is there no whistle or smoke coming out during a test? Why would a glove test not work on the 3.2 ? Why am I seeing the same DTC's and LTFT after driving it for a while - I started with that replacement first.
- MAF
I did not clean it as mentioned in my previous post. I saw a dirty sensor and decided to replace it. Car is from ’08, why is dirty? Maybe the previous owner did not do a great job replacing filters.
- Fuel
I was on an empty tank, took it to Shell and got the good fuel. Took it for a spin (with the old MAF) after that.
- Intake
Maybe there is a crack somewhere or the throttle body is stuck at idle. I could take it off for a better inspection.
- Exhaust
Did not remove the heatshields because there are no noise concerns. Will do that as well.
- Spark plugs
Agreed, they look a bit oily. However, all of them look oily and not only #6. Could be from the previous PCV valve so I will buy new ones and drive a bit around.
- Injectors
Bought them from an injector cleaning shop here in LA, gave them my old ones so can’t swap it back. Drove it for a while after swapping. Same LTFT.
- Fuel pump
I think the pressure and duty cycle shows it is fine looking at the video I posted previously. I replaced the fuel filter about a year ago.

All to say, I think it is important to understand what is going on first. Can somebody share their experience with STFT and LTFT at idle or WOT?
- Is it normal that the LTFT goes to 0% and STFT to 20-30% at WOT ?
- Does the STFT take over from the LTFT on WOT ?

If yes, I have an overall lean issue. If not, I have a vacuum issue that is not there during WOT (LTFT to 0%)

Reading up on documentation about emissions, I believe that is a different system level check. Right now I have the feedback that my system is lean independently from emissions. The upstream wideband 02 sensor tells me if I am running lean/rich. The downstream 02 sensor tells me if my cats are working.

My next steps
- Buy new spark plugs and drive around for a while
- Remove heatshields and inspect exhaust
- Remove intake and inspect

Maybe I am wrong and the PCV unit is not good. I am just hesitating because I had the same DTC and errors before and after swapping it. Even after driving it some additional mileage.

[chitownV]

Anyone else with LTFT and STFT with experience? Huh?

Hey, you might want to go back and read how I tried to help you. You will know the LTFT has had enough time because the emissions will be ready. I already mentioned this.

Since you don’t have enough experience, or the right experience, let me help you one last time. I’m not your teacher so this is the last. WOT usually has a fixed fuel & ignition table...aka the engine tune. The O2 sensor readings won’t alter it. Again, what you are saying is irrelevant for the LTFT at WOT.

You have already been given enough (correct) information and resources.

Good luck with your diagnosis and learning new things.