[frisbeeguy]

Hello everyone,
I have a 2007 BMW X3 (same N52 Engine), and randomly today the car struggled to shift properly (the 4x4 light flashed, and often in stop and go traffic, it would stall before shifting properly....on the highway it shifted alright, however, I did still notice that transmission needle "bump struggle, kept going up and down a little" I pulled the following codes with ISTA:

DME 0029E1: Fuel-air mixture too lean, Fault can activate a warning light (emission warning light or engine warning symbol)
Environment conditions:
Frequency: 1
Logistics counter: 40
SAE diagnostic trouble code: P0174
Engine Temperature: 99.75 Degrees Centigrade
Air Mass calculated: 92.24 mg/Hub
Engine Speed: 704.1/min
Adjustment Inlet Valve Model (factor): 0.87

DME 0029E0: Fuel-air mixture too lean. Fault can activate a warning light (emission warning light or engine warning symbol)
Environment conditions:
Frequency: 1
Logistics counter: 40
SAE diagnostic trouble code: P0171
Engine Temperature: 99.75 Degrees Centigrade
Air Mass calculated: 92.24 mg/Hub
Engine Speed: 672.1/min
Adjustment Inlet Valve Model (factor): 0.87

Also checked for transfer case codes with INPA since the 4x4 light is also used by that as well as DTC/DSC...no fault codes for transfer case or the DTC/DSC system....according to INPA no transmission fault codes, and ISTA only gave the 2 codes I posted above once I went through the whole identification process..which is like a minute to 2.

To Add: The sparkplugs were all replaced only 2,000 miles ago, all coilpacks were replaced around 20K miles ago. This week the valve cover gasket was replaced along with the eccentric shaft sensor.
So far I'm thinking that it could be a fuel injector issue (which means I'd have to clean them)? Or it could be MAF (but that's the last item to check), or it could be the VANOS Solenoids? I'm not really sure where to start for diagnosis.

[GoRomeo]

Originally Posted by frisbeeguy

Hello everyone,
I have a 2007 BMW X3 (same N52 Engine), and randomly today the car struggled to shift properly (the 4x4 light flashed, and often in stop and go traffic, it would stall before shifting properly....on the highway it shifted alright, however, I did still notice that transmission needle "bump struggle, kept going up and down a little" I pulled the following codes with ISTA:

DME 0029E1: Fuel-air mixture too lean, Fault can activate a warning light (emission warning light or engine warning symbol)
Environment conditions:
Frequency: 1
Logistics counter: 40
SAE diagnostic trouble code: P0174
Engine Temperature: 99.75 Degrees Centigrade
Air Mass calculated: 92.24 mg/Hub
Engine Speed: 704.1/min
Adjustment Inlet Valve Model (factor): 0.87

DME 0029E0: Fuel-air mixture too lean. Fault can activate a warning light (emission warning light or engine warning symbol)
Environment conditions:
Frequency: 1
Logistics counter: 40
SAE diagnostic trouble code: P0171
Engine Temperature: 99.75 Degrees Centigrade
Air Mass calculated: 92.24 mg/Hub
Engine Speed: 672.1/min
Adjustment Inlet Valve Model (factor): 0.87

Also checked for transfer case codes with INPA since the 4x4 light is also used by that as well as DTC/DSC...no fault codes for transfer case or the DTC/DSC system.

To Add: The sparkplugs were all replaced only 2,000 miles ago, all coilpacks were replaced around 20K miles ago. This week the valve cover gasket was replaced along with the eccentric shaft sensor.
So far I'm thinking that it could be a fuel injector issue (which means I'd have to clean them)? Or it could be MAF (but that's the last item to check), or it could be the VANOS Solenoids? I'm not really sure where to start for diagnosis.

Since you recently replaced your VCG, check for loose or cracked vacuum hoses. Make sure all its back in place correctly... Pretty much a good visual inspection.

[frisbeeguy]

Checked all vacuum hose connections plus went over the job I did for the valve cover gaskets. I don't see anything wrong, and there's no oil leaks....to add: even before the VCG job, upon a cold start, the car shakes a bit side to side like its trying to adjust itself, then the engine sounds like normal....I'm not sure if this is normal or not since some posts say it is and some don't...I thought that the eccentric shaft sensor would fix that. What I do know is a lean condition means that there is more air and less fuel...so either the hoses can be damaged (but they look normal and fine to me...and that PCV hose (near the firewall) also clipped into the VCG fine...no broken tabs), the actual PCV in the VCG is bad, one of the fuel injectors is clogged causing less fuel to go into the combustion chamber, the fuel pump is not delivering enough fuel, but really these are all "possibilities." I don't want to just start replacing a lot of stuff, and discover that the issue is something else...so as of now I am stumped.
Edit: So I removed the oil cap with the engine on, and there is very mild resistance, feels easy to remove, so I guess that means that there is no vacuum leak....I'll post videos on engine noise soon. I also checked the engine air filter, and it is clean.

[frisbeeguy]

First video is engine after startup when it's warm:

Second is on a semi-cold start, slightly can hear the engine "adjust" itself:

Third is the Engine Idling sound, after 30 seconds:

[GoRomeo]

Originally Posted by frisbeeguy

First video is engine after startup when it's warm:

Second is on a semi-cold start, slightly can hear the engine "adjust" itself:

Third is the Engine Idling sound, after 30 seconds:

videos dont work... video unavailable..

[frisbeeguy]

I updated the links...it should work now.

[Noir]

My e90 did something similar in terms of stalling when I first got her almost 2 years ago..
I replaced my: plugs n coils/VCG/Eccentric shaft sensor/MAF/Vanos Sensors

And the stalling issue went away...
I did it all at once though (minus the VCG/ESS since I just got it and I wasn't too comfortable taking it apart that much..) so I can't say what did the trick..

[GoRomeo]

hard to tell from the videos... look and sound normal to me. I have the same engine... and these N52 engines have like a hick up when it comes down to idling.. mine does it too. I know I am due for coils but other than that I never encountered stalling since I got mine in 06...

I will suggest resetting codes and read them again. hopefully you get a more solid reading. how many miles do you have? Read on Oxygen sensor maybe you are due for one... ?

[frisbeeguy]

Have 105,000 miles. I did reset the codes. I'll look more into it tomorrow.

[simon]

I know you said you've already checked all vacuum hoses and VCG, but if you're lean on both banks I think it's gotta be either the MAF or a vacuum leak.

Use a scan tool to look at short term and long term fuel trims. At idle what are your short term fuel trims? Should be at, or very close, to 0. If they are far from 0 on the positive side, this means your car is trying to add fuel to compensate for the lean condition. If it's far off (more than 10% or so) on the positive, raise the engine speed to 3000 RPM or so and hold there for 30 seconds. What happens to the fuel trim? If it goes back down to acceptable levels, then there is a vacuum leak.

If the fuel trims never seem to improve, then we can start to look for other things. An injector is possible, but if both banks are lean then we have more than one injector (one at least in each bank) that shat the bed at the same time. This is slightly unlikely.

Another thing common to both banks which can potentially cause a lean condition is the MAF. Try cleaning that.

My money is on a vacuum leak somewhere. Get some carb cleaner and start spraying all around your valve cover gasket and all vacuum lines. Don't forget around the throttle body and anything past the MAF, really.

Simon

[frisbeeguy]

Originally Posted by simon

I know you said you've already checked all vacuum hoses and VCG, but if you're lean on both banks I think it's gotta be either the MAF or a vacuum leak.

Use a scan tool to look at short term and long term fuel trims. At idle what are your short term fuel trims? Should be at, or very close, to 0. If they are far from 0 on the positive side, this means your car is trying to add fuel to compensate for the lean condition. If it's far off (more than 10% or so) on the positive, raise the engine speed to 3000 RPM or so and hold there for 30 seconds. What happens to the fuel trim? If it goes back down to acceptable levels, then there is a vacuum leak.

If the fuel trims never seem to improve, then we can start to look for other things. An injector is possible, but if both banks are lean then we have more than one injector (one at least in each bank) that shat the bed at the same time. This is slightly unlikely.

Another thing common to both banks which can potentially cause a lean condition is the MAF. Try cleaning that.

My money is on a vacuum leak somewhere. Get some carb cleaner and start spraying all around your valve cover gasket and all vacuum lines. Don't forget around the throttle body and anything past the MAF, really.

Simon

Thanks for the Info! For monitoring fuel trims, I plan to use ISTA. I go to measuring devices and read the fuel trims like in this post (the second one)? http://www.bimmerfest.com/forums/sho...d.php?t=898870

[yupetc]

Vacuum leakage after the MAF. Or the MAF is simply crapping out without showing the fault codes.

[hassmaschine]

Do you asaptations change, or are they stuck at 0%?

[simon]

Originally Posted by frisbeeguy

Thanks for the Info! For monitoring fuel trims, I plan to use ISTA. I go to measuring devices and read the fuel trims like in this post (the second one)? http://www.bimmerfest.com/forums/sho...d.php?t=898870

I'm not familiar with ISTA, but there are a million people smart enough to help out with that. I'm taking a wild guess that additive is long term, since long term fuel trim is like an over time fuel trim. I can't make sense of why short term would be called multiplicative and that number and unit don't really make sense for fuel trim either.

Sorry, someone smarter than me needs to help with ISTA.

Simon

[frisbeeguy]

So today I monitored the trim levels with ISTA (surprisingly more straightforward than VCDS), and here are the results:
This is the first under idle (when I start up the car):

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This is the second when I raise the car to 3000 rpm:

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Third comparison of when I raise the car to 3000 rpm:

View post on imgur.com

And here's the 4th pic after I ease of the accelerator from 3000 rpm and let the car idle:

View post on imgur.com

Do these values look normal? I also tried disconnecting the MAF and left it disconnected for 10 seconds, and engine noise started increasing so I connected it back on.

[PhaseP]

As stated earlier, you had your valve cover gasket replaced and now you have this problem.
Lean means there is air coming into the engine after MAF sensor, which it didn't measure. Or your injectors may be putting less fuel but that is very very unlikely on an N52. I am yet to hear anyone's N52 injector fault. And it is even twice unlikely that at least two injectors that are on separate banks are faulty at the same time causing both banks to report lean error.

So most likely vacuum leak. Check the vent hoses, but also check all around the valve cover gasket. Gasket may have been rolled and pinched during installation. You can use a small inspection mirror sold at auto stores to look all around the valve cover. If it did happen you are likely to see oil in the are gasket is pinched. This may allow in air too, causing lean.

[PhaseP]

you can also check if you have vacuum leak from your PCV/CCV on the valve cover by attaching a tube to the nipple and while engine is turned off "gently" blowing air into it. You should be able to blow in only a small amount of air to enough to push the membrane and close the valve which would be done in an instance. If you can blow in air continuously, then membrane is torn and causing vacuum leak.

More detailed info on how to test and all:

https://vanos-bmw.com/product/111275...53-11127548196

The nipple has a dust cover plug, you can just pull it off to test and put it back when done. That is if it is still there. It may have fallen off already, which is no big deal if it did.

[PhaseP]

Originally Posted by frisbeeguy

Do these values look normal? I also tried disconnecting the MAF and left it disconnected for 10 seconds, and engine noise started increasing so I connected it back on.

I am familiar with INPA screens on those, but the ISTA ones you linked are actually showing just a bit rich condition since the multiplier is negative.
To get good reading you need a warmed up engine. And those multiplier values shown are not enough to throw error, the threshold for error throwing +/- 15% or 20%, don't remember exact number.

See my post here for relevant INPA screens, but they will be showing same information maybe in different format:
http://www.e90post.com/forums/showpo...28&postcount=8

You may be having lean condition certain times, which could be your PCV.

[frisbeeguy]

Originally Posted by PhaseP

I am familiar with INPA screens on those, but the ISTA ones you linked are actually showing just a bit rich condition since the multiplier is negative.
To get good reading you need a warmed up engine. And those multiplier values shown are not enough to throw error, the threshold for error throwing +/- 15% or 20%, don't remember exact number.

See my post here for relevant INPA screens, but they will be showing same information maybe in different format:
http://www.e90post.com/forums/showpo...28&postcount=8

You may be having lean condition certain times, which could be your PCV.

So I tried the PCV test, and it passed that. I uploaded 2 videos, one in which I drive the car for 0.4 miles approximately (basically did a 17 mile trip all highway to get the engine warmed up before doing the city driving test), and another in which I rev the engine to 3000 rpm. Do the values look normal to you?

[PhaseP]

I think your videos show that when there is load on the engine/or rpm is high the fuel trim goes back towards 0%.

When there is little load (like coasting) or rpm is low (idling stationary) fuel trim goes above 10%.

I think that indicates vacuum leak.
Computer is trying to compensate unmetered air (introduced after MAF sensor) by adding more fuel (positive fuel trim percentage).

The PCV can have two different leak. One is the membrane tears, then it allows ambient air to get into crankcase. Blowing into it from that nipple while engine is not running, or even holding your finger when engine is running to see any vacuum is applied to that nipple is ways to diagnose this leak.
The other leak of PCV happens when it is supposed to leak the crankcase from too much intake vacuum. It is a "controlled vacuum" valve. If it doesn't close when there is too much vacuum, as in idle due to throttle plate being closed, then it causes air go through crankshaft seals into the crankcase. This will be apparent if it is difficult to open the engine oil cap due to too much vacuum on idle, or squeling noise from crankshaft seals. And unexplained oil consumption. You don't seem to have these problems.

Again check your valve cover for cracks, crimped rolled over gasket, not well seated gasket around spark plugs.

Good luck!

[frisbeeguy]

Originally Posted by PhaseP

I think your videos show that when there is load on the engine/or rpm is high the fuel trim goes back towards 0%.

When there is little load (like coasting) or rpm is low (idling stationary) fuel trim goes above 10%.

I think that indicates vacuum leak.
Computer is trying to compensate unmetered air (introduced after MAF sensor) by adding more fuel (positive fuel trim percentage).

The PCV can have two different leak. One is the membrane tears, then it allows ambient air to get into crankcase. Blowing into it from that nipple while engine is not running, or even holding your finger when engine is running to see any vacuum is applied to that nipple is ways to diagnose this leak.
The other leak of PCV happens when it is supposed to leak the crankcase from too much intake vacuum. It is a "controlled vacuum" valve. If it doesn't close when there is too much vacuum, as in idle due to throttle plate being closed, then it causes air go through crankshaft seals into the crankcase. This will be apparent if it is difficult to open the engine oil cap due to too much vacuum on idle, or squeling noise from crankshaft seals. And unexplained oil consumption. You don't seem to have these problems.

Again check your valve cover for cracks, crimped rolled over gasket, not well seated gasket around spark plugs.

Good luck!

A lot more of trying to diagnose today...

Checked the gasket (with a mirror like you suggested) and it looks properly seated to me, also pulled the coils to check and they're fine too...no oil inside...I was thinking of having the intake system smoke tested, but now I think I don't need to anymore....Learned about the "History memory Portion" of INPA today...usually when I click "Read Error Memory," I see no errors...wish I knew about that sooner...didn't know that recent errors are also stored in the History memory portion....surprisingly ISTA said no errors, but INPA showed these errors I saw that these errors correspond to the current mileage that I have driven the car for....and today (170032 km), the car gave a fuel mixture lean code for both banks 1 and 2...but before those codes I see errors for MAF issue...and prior to these there are occasional faults for the stuck "intake" VANOS solenoid...so now I'm thinking to replace just the intake VANOS solenoid (or should I replace both?), and as for the MAF, clean it then drive again to see if errors disappear or should I just replace it (cause I see a lot of MAF codes)? I added all the image links for the faults I pulled...the first the oldest and the last the newest.

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[PhaseP]

The Maf errors maybe from the time you disconnected Maf sensor for troubleshooting. Still it won't hurt to clean it. Make sure you use Maf cleaner spray, and spray inside the white plastic crevice, the hot wire sensor is there not visible. The visible bead thing is air temperature sensor, won't hurt to clean it too.
There is lots of info on vanos selonoids in the forum if you search.