XC90 Lean Bank 1&2 Issues

[Hofstad]

Hi guys

I need your help on my '08 XC90 with the 3.2 engine. Since a few weeks I have the Check Engine light with the following codes:
ECM - P017100 System Too Lean (Bank1)
ECM - P017400 System Too Lean (Bank2)
ECM - P030000 Random Misfire Detected
ECM - P030400 Cyl4 Misfire Detected
ECM - P030500 Cyl5 Misfire Detected
ECM - P030600 Cyk6 Misfire Detected

I used to have some starting problems, these were solved after changing the MAF sensor
Looking at the forum and previous posts I was convinced I had the PVC issue that is common for these engines. Unfortunately, after replacing it still the same issue . I smoke tested the intake before and after the throttle body, all good except a small bit of smoke around the intake hose but fixed that with a new hose clamp . No exhaust leaks it sounds fine. Starting cold it sounds a bit rough and lacks a bit of torque in the low RPM. Smells like fuel after starting it.


To summarize, I tried out / swapped the following things:
- MAF
- Camshaft positioning sensor
- PCV
- Fuel Filter
- Fuel Pressure Sensor
- Injectors
- Air filter
- O2 Sensor

After replacing parts and borrowing sensors from my buddy his car, I purchased a VIDA to get some more information.
In general, the LFT trims are at 24% on both banks (very identical). The SFT trim is around 20% and hoover around 10% when I rev at 2000rpm.

All to say, I am clueless at this point. The injectors, pressure sensor and filter proved it's not the fuel delivery. The smoke test (I pressurized well) did not show me a huge leak. I tried another 02 Sensor to see if one of the banks will get better, but no result.. The only thing I don't know if the ECM-Camshaft is to far off with 72 CA ? (sounds high looking at it) which could indicate some chain issues? 02 Sensors have a 1 AFR with the adapted fuel trim.

Obviously I reset the adaptions and DTC's to make sure it's not a ghost error message.

Please help me out here, maybe I am missing something.

[chitownV]

What is the history of the vehicle? How many miles? Etc. etc.

It sounds like the engine is trying to richen up with your LTFT. So, it’s not okay, yet you are still getting a lean code. Mine runs at about +/- 1%.

A couple things, see the live behavior, not just a snapshot. What happens to the fuel pressure as you accelerate with load? How is the duty cycle of the fuel pump? When you click on the lean codes, VIDA should give you the conditions when it triggered.

What do you mean you tried or replaced the fuel injectors? What did you actually do? You can purchase on Amazon a cheap injector cleaning kit with electronic activator to clean and inspect the spray of each injector. Don’t just swap or do something without confirmation of something working well. You could have some bad injectors. If you remove the injectors, get new o-rings and they are cheap.

See what the primary O2 sensors are doing, that there isn’t a wiring harness issue.

What do the spark plugs look like? Are they dark, like it is actually running rich, but the O2 sensors are incorrectly reading, or is it looking whitish like it is accurately reading lean?

[Hofstad]

The car has 178k miles on it, air/oil filter and plugs replaced on a yearly basis. I think the lean code and LTFT are correct, from the 02 sensor it reads a lean combustion and therefore it keeps adding fuel to compensate for that.

However 25% is a lot and indicates something big or obvious right ? Like a huge vacuum leak or faulty fuel delivery.

Over the weekend I will make some videos at warm idle and acceleration. What data should I capture? I'll take some pictures from all spark plugs as well.

Duty cycle of the pump is around 55% at 2000rpm with 380kpa (warm).

Yes I replaced the original injectors and o rings with remanufactured Denso injectors- same Error code and LTFT before and after.

[chitownV]

Please be complete if you are going to give information so questions don’t need to be repeated over and over again. Good info like, what brands you used for parts as some parts are brand specific for working without issue.

***What is the history, again? Did you own it for the past 10 yrs or are you assuming oil/filter was changed each year. What was done when and what was replaced and what brands were used.

What oil have you been using and do you have any oil consumption? Is your oil filler cap sealing well?

Did you replace the entire PCV or just the diaphragm/cap kit? I ask because the misfires were at cyl 4, 5, 6, where a failing PCV can start to dump oil in cyl 6 even without whistling.

Did you open the listed code in VIDA and see what the other info was at the time the lean code triggered? Then try to figure out what is wrong with the given info? In VIDA you can trigger the intake manifold flaps to check they are working.

Fuel delivery is based on load as well, not just rpm. What happens on load as your rpm’s climb higher than 2k rpm? Also, see the fuel pressure as you are on load.

I asked about the spark plugs because the O2 sensors could read lean, but it truly isn’t in the engine. An example would be a rust hole or leak from the exhaust manifold/cats or down pipes/flex pipes affecting the readings. You might not hear a leak. You have to get dirty and look in there. Take pics so you can zoom in.

I go through a lot of the 3.2 maintenance and issues, plus most a lot of links to get more info,
In this post,
https://www.swedespeed.com/threads/the- ... st-7332383

[Hofstad]

Thanks for your reply, you have a lot of impressive posts and history with this engine! In the last few days I tried to gather some information. I’ve had the vehicle for over 3 years and did not change much except the air, fuel & oil filter + oil.

No oil or coolant usage at all, I did replace the complete PCV unit and not only the membrane.

Some brand info on the parts I used after I started to have some issues.
- MAF - Delphi
- Camshaft positioning sensor – FCPEuro Genuine Volvo
- PCV - https://www.carparts.com/Valve-Cover/Re ... RV32040001
- Fuel Filter – FCPEuro Mahle
- Fuel Pressure Sensor – FCPEuro Bosh
- Injectors – Reconditioned Denso
- Air filter – FPCEuro Genuine Volvo
- O2 Sensor – Denso but no replacement - swapped it back to back with one from a friend of mine. Came out grey colored (no picture)

About a year ago I did the spark plugs as well, used NGK-6481 plugs. Please see below for the pictures how they came out today.
I did make a video like you recommended, hopefully you can see it in the attachments.
General notes
- LTFT goes to 0% at WOT
- STFT goes to 20-30% at WOT
- Fuel pressure stays around 370Kpa and 66%

Recording 2023-07-04 151938.mp4

(731.56 KiB) Downloaded 310 times

Looking at this I feel like it still could be a vacuum related issue, or the intake flaps like you mentioned. Can I activate the flaps while the engine is running? What result do we expect ?

I did a proper intake smoke test both before and after the throttle body
- Removed the intake after the MAF and attached the smoke machine. There was a tiny bit of smoke coming out between the plastic hose and throttle body. Retorqued the hose clamp and that problems was solved.
- Attached after the throttle body where the EVAP system is, no smoke.

During both some tests there was pressure in the crankcase and no smoke coming out of the engine. Smoke was visible when removing both the dip stick or the oil filler cap.

Clicking on the VIDA error message’s both of them capture lean during idle

[chitownV]

Good info. Did you clear the codes recently because in the video the LTFT seems like it needs more time to get enough driving info. The STFT is where it should be. The VIDA screenshots look like what it would be for the codes, nothing additional pops out.

My first suspect would be the cheap PCV. Since that has caused lean/rich issues with the 3.2 and most engines. That would be something I ensured was one of the good ones.

The pics of your spark plugs are oily. Why do you have oily threads? Is it leaking oil from up top?

Is your oil cap leaking from its o-ring/gasket? A new filler cap gasket is a few bucks at FCP.

Oily plugs could indicate the PCV. If the plugs are only about a year or so old, they look worse and the ceramic looks like it overheated or ran hot, like you are running lean. I would have assumed those plugs were 30k-50k miles old. Those need to be replaced. If you were running lean and hot, the plug tips should be more whitish, but I’m guessing a bad PCV was dumping oil into the cylinders.

My second suspect would be to look at the MAF. Original Volvo is Denso and just like how sometimes different brand O2 sensors don’t play nice, the brand of MAF can be more sensitive. A new Delphi MAF may have helped the starting issue, but it might not be reading accurately or accurately in sync with Denso units. FCP doesn’t have it listed for the ‘08 XC90 3.2, but this Denso and part number is correct: https://www.fcpeuro.com/products/volvo- ... o-197-6020
Here is the part & number from Volvo. It fits all the 3.0T/3.2/4.4 years: https://www.volvopartswebstore.com/prod ... 58471.html

I would start with your work again and the parts I mentioned. Then see how the baseline numbers look.

[Hofstad]

Thanks!

No leaky oil cap, don't know why the plugs look a bit oily. No oil around the spark plug area, maybe leftover fuel from running it cold (only ran it cold for 1 minute from my driveway to my garage).

Two notes:
- Would there be a way to verify the PVC before replacing it with another one? If not, what would be a good PVC you could recommend?
- I still have the original MAF sensor, I can replace it and see what happens.

[chitownV]

Lol, just an FYI, PVC is the plastic pipe.
PCV is Positive Crankcase Ventilation.

For the price you bought that PCV, I would just jump straight to using a good known one. It’s not an all or nothing part like an electrical sensor. Who knows the material of the diaphragm, the design of the mold, or if there is good quality control. It could have issues at certain vacuum levels, rpms, be partially working, etc.
I would go with the OEM one at FCP as that has been proven to work. Looks like you are spending more money outside of the cost of this PCV, so good to just know you have a verified working part. https://www.fcpeuro.com/products/volvo- ... 0-31319642

You can try the original MAF, but I thought that had starting issues and perhaps a code. I don’t like cleaning these MAFs with high miles since it’s easy to damage them. With your 170k+ miles, it’s a good idea to get a new Denso one rather than clean. If you cleaned the MAF, well, who knows what that did.

Again, know for vital parts that can make huge swings in the A/F that you have sound footing and baseline with verified brand parts. You already smoke tested so that helped reduce possibilities.

Fuel should not have gotten on the spark plug threads like that. Some of the fuel should have also evaporated. Get new plugs with the other parts then reassess.

If I were you, I’d also change the oil filler cap gasket (o-ring). It’s a few bucks and can prevent any future oil and vacuum leaks.

I don’t know what fuel you are putting in there, but use Premium for now until you can improve the both banks lean issues and the computer has had time to adapt to the new parts, like the LTFT, ignition, etc. I also don’t know what oil you use, but if any of the oil passages or screens for the VVT or cam profile switching are partially blocked with carbon from using non-synthetic oil, I’d start using Mobil 1 0W-40. I forget where, but someone had a screen partially blocked and started using Mobil 1 0W-40 which helped. Then they changed one solenoid and it would actuate faster than the other original one. Use good oil.

I don’t know who rebuilt your fuel injectors, but I only see GMB as the reputable ones that I would use. Too many times people got counterfeit or non-working injectors from Amazon, eBay, or other sources. If you did the work, changed the screens, and even used a cheap injector cleaning kit to verify the spray was wide and good, then that’s fine. Like this one https://a.co/d/aEZjzfc

So, start with verified, sound parts that work as your baseline. Then reassess as it will remove some of the factors that could cause the lean codes. This is one reason why shops don’t like to use customer parts.

[pgill]

First: ChitownV is giving you excellent advice..........continue to follow that advice


If I was fixing this XC90 I would do the following

1) Verify that the PCV is working using the glove test and if I had any doubts then I would get an aftermarket PCV marked with FOMOCO

2) Get a set of Denso Iridium TT sparkplugs and torque them to specification

3) Disconnect the MAF and reset the code and see if the code returns when I do a test drive using the MAP sensor only instead of the MAF and MAP


The reason for item #3 is because a false air leak after the MAF can set exactly the codes that you are finding. (if the problem goes away when only using the MAP then you need to find the false air leak)

Here is a video.

Note: at 0:48 you will see the problem but remember that a loose in take tube or misaligned intake tube could cause the same problem. Anything that would allow the air to get to the engine without passing by the MAF.



Good Luck

Paul

[Hofstad]

Guys, lot of helpful comments.

Some additional work I did tonight
- Put premium Shell fuel in the tank (was almost empty), no difference
- Did the glove test and it tried to suck in the glove a bit, but it did not pull it in completely. I feel like it's working properly, no whistle or anything.
- Did an A-B comparison with the old and new MAF - LTFT still the same behavior and lean codes
- Pulled the MAF completely, instant idle problems and bunch of MAF errors- LTFT still the same.
- Pulled the timing solenoids , intake manifold actuators -again a bunch of errors but no difference in LTFT

Two weeks ago i rented a smoke machine for the intake, found a small leak on the plastic tube that goes from the MAF to the intake throttle body. Fixed it by re tightening that clamp (no significant difference on LTFT) . I connected the smoke machine before and after the throttle body. When removing the oil filler cap or dip stick there was smoke coming out so I think it went through the whole intake - please correct me if I am wrong-

I am fine with getting new spark plugs but would the engine give me a rich or lean value when there is un-ignited fuel in the exhaust?

The engine sounds fine but I will try to remove more exhaust heat shields. There is not a lot of exhaust between the cylinder head and O2 sensors so if there would be a leak it needs to be around that area. Also, both LTFT's are the same so it would be coincidence both of them leak exactly the same amount. I did not do the exhaust smoke test because it sounds fine, maybe I should've done that as well.

I also tried activating the intake manifolds actuators while the engine was running but I think I am not not allowed because it did not do anything. I activated them with the engine off and both work and sound the same.

Is there anywhere else there could be vacuum leak I missed? The vacuum pump for the brake system could not leak internally or so ?

// Edit //
Can somebody verify the throttle position idle value ? What if the throttle body is stuck or giving me incorrect values at idle ? See below for my values