[alexwhittemore]

So I replaced my plugs just now. They were more worn than I'd have expected for 35k miles on them, but still no luck fixing the underlying issue. I was curious about just how much they'd worn, so I measured them all (probably not the MOST accurate with buildup and the crescent wear pattern, but close): 1.38mm/1.37/1.33/1.27/1.27/1.27. that strikes me as weirdly uneven between 1/2, 3, and 4/5/6.

Anyway, new coils tomorrow, then I probably just give it to the indie and hope they don't screw me.

[DaanBMW]

OK, I did the experiment that I was most hopeful for solving my rpm drop issue. I disabled the VVL part of the Valvetronic, to see if that might trigger some changes.

The VVL disabling was done by unplugging the ESS. Car worked fine after an initialization. Meaning while there was some power loss and change in driveabilty, there were no codes or nasty side effects. The car seems to get quite a bit more thirsty with the VVT disabled, fuel economy dropping right away. Acceleration is also not as great, so is the ability to coast in (higher) gear, i.e. you need to downshift like you normally do on manuals :-)

As far as diagnosing my actual issue it made things WAYYYY worse. The car symptoms were present now even when car was cold, and MUCH more frequently. So my thoughts about issues being related to closed loop operations or Valvetronic are out the door now...

[DaanBMW]

To recap: My issue is that the rpms are dropping to/from idle only.
** The #1 issue is the hard rpm drop when taking it out of gear after coasting in gear. When running a/c - due to the additional load - this rpm drop can lead even to killing the engine.
** The hesitation upon takeoff is almost secondary compared to this, just imagine you are turning right and suddenly your power steering is gone.
** Never had any codes, and idle rpms are steady (no chasing).

Things I replaced so far with no fix:
- spark plugs
- coils
- maf
- solenoids
- VVL motor
- camshaft positioning sensors
- Vanos check valves
- fuel pump control unit
- checked & cleaned throttle body
- my car has no DISA (n52 has single stage intake), and no EGR
__________________________________________________ _______________

Any suggestions are welcome. I had the fuel pump & fuel relay on my list, but after major330i 's report I'm on the fence on that.

[alexwhittemore]

Originally Posted by DaanBMW

The #1 issue is the hard rpm when taking it out of gear after coasting in gear. When running a/c this drop can lead even to killing the engine.

I think our respective root causes are probably different, or at least not present to the same degree. I'm not experiencing RPM drop, at least not really - if I'm idling on the highway at, say, 1700rpm, and I get on the gas a little to, say edge up a few MPH past someone the next lane over, my RPM might drop by 100 before then more-slowly-than-normal climbing. It's mostly a power loss and a hesitation to increase output.

I'm curious though, have you done a smoke test or a compression test? There's always the possibility it's a more basic and traditional problem. And the tops of my pistons, looking down in while changing spark plugs, do seem pretty gunky - but I have no frame of reference for what they SHOULD look like at 115k miles, either.

[steifan]

Similar issues here with my euro 325i N52B25.

Wall of text:

Noticed when I bought the car in 2014 that the car would often behave strangely when the engine was hot and after driving "normal" with the cruise control engaged the car would "jerk" once and then hesitate when disengaging cruise control and then run week in the lower rpm power band but decent in the upper rpm's, then suddenly it would run "good" with decent low down torque. It didn't bother me much and the car didn't throw any codes (checked with generic Torque and INPA) but I thought there was some connection to the spark plug interval coming up so I replaced those with no improvement. Then on a summer 2 years ago I got a code for the MAF sensor reaching upper limit. Tried cleaning the MAF with CRCs MAF sensor clean, still threw the codes. Car ran better with MAF disconnected so I ran like that for a few weeks. Bought a new MAF and replaced it, no codes. The sporadic hesitation was still there so I started looking into forums and found the VANOS solenoid problems, last summer I tried cleaning the solenoids with brake cleaner and compressed air 2-3 times but it didn't really help (even had the solenoids soaked in isopropanol for 6 hours). Bought new solenoids and put them into the car this spring and the car ran better but the problems still came back. Funny thing is that the car sometimes is so powerful in low RPM's you would think that the tires would tear off on freeway ramps, but I'm guessing that's how it is supposed to run. During this summer the car started throwing the codes P00012, P00015 and P00016 when car was at normal operating temperature, haven't had those codes before and I already replaced the solenoids. The thing is that this summer has been hotter than before and temperatures have been above 86°F and I believe that there is a connection to high outside temperature and the engine struggling. I tried cleaning the VANOS solenoids (the new ones), and switched sides but that didn't help so I did an oil change last week specially checking the oil cap center piece which seems to be all-right, been running the old oil for 3000 miles. Cleaned the VANOS solenoids again during the oil change but the car still threw codes directly after. I found that VANOS could be tested in INPA so I tried that a few times and it seems like the VANOS-solenoids is getting signal and actuating (dunno if it's just set values, hopefully feed back values) but the exhaust camshaft doesn't seem to move during the diagnostic test. Codes are thrown for both sides. I will try the diagnostic again today.

The sporadic issues seems like an electrical fault to me as a mechanical problem would be present "all the time", the car runs really well some times and then the engine does one "jerk" and suddenly runs poorly. Thinking about replacing both cam shaft position sensors as they seem to fail on other cars (intake side on my E46 323Ci and crankshaft sensor on my old Volvo).


Summary:

Car: Euro BMW 325i 2006, N52B25 218hp
Owned since: 2014 (used as summer only car, to spare it from harsh Swedish winters)
Mileage: 51000 miles in 2014, now around 70000

Problems:
* Sporadic low rpm hesitation after a "jerk" when coming out of cruise control for a period, 2014-2017
* Often check engine light and poor performance in hotter weather (above 86°F) from 2018, but can run really good sporadically.
* Sporadic uneven idling, car would sometimes increase idle to 1500rpm and than drop down to around 500.

What I've tried:
New MAF-sensor (because of fault code for high limit/similar)
Spark plugs (after interval)
New VANOS solenoids (after 3x cleaning attempts)
Tighter oil service intervals

What I'm willing to try:
Cam shaft position sensors (because the problems are sporadic - electrical issues? cables getting warm?)


Anyone solved any problems with new camshaft position sensors on N52/N53 engines?

[DaanBMW]

Originally Posted by steifan

Anyone solved any problems with new camshaft position sensors on N52/N53 engines?

My main issue is also hi-ambient temperature related, but a bit different still. See 2 posts above. The cam pos sensors did not solve it on my end.

Could it be electrical ? I guess, and that would explain the heat making it worse. But the random nature is what throws me off, as my rpm drop is not happening all the time; it's dropping 5-6 times out of 10, with 2-3 times quite severe causing the engine to chase past idle speed as it attempts to recover, and maybe 1 time leading to the engine shutting off (only with a/c on).

I keep saying I need to take a video of this, but keep forgetting...

[steifan]

Originally Posted by DaanBMW

My main issue is also hi-ambient temperature related, but a bit different still. See 2 posts above. The cam pos sensors did not solve it on my end.

Could it be electrical ? I guess, and that would explain the heat making it worse. But the random nature is what throws me off, as my rpm drop is not happening all the time; it's dropping 5-6 times out of 10, with 2-3 times quite severe causing the engine to chase past idle speed as it attempts to recover, and maybe 1 time leading to the engine shutting off (only with a/c on).

I keep saying I need to take a video of this, but keep forgetting...

Might be wiring to cam shaft position sensors that heat up too much when the ambient temperature is high. Would also explain why some people still have problems after replacing VANOS solenoids and camshaft position sensors. Maybe the heat shielding in the cable harness is degrading and is most prone to fail on the camshaft position sensors or the VANOS solenoids because of their position. PURE SPECULATION: The ECU might lose the feedback from the camshaft position sensors or the actuating of the VANOS solenoids when the cables are at a certain temperature causing higher resistance (might not be plausible). That would make it very hard to troubleshoot the problems in a "cold" ambient environment. And we also have the variable oil pressure and variable coolant temperature to think about, oil pressure drops and coolant temperature increases when the car is cruising (+17% higher coolant temp) - if you mix those three: cable heating up, the oil pressure is relatively "low" and the engine has even higher temperature and then you want to go full throttle to pass someone on the highway which results in a check engine light and poor performance because of those 3 combined - it fits my main problem, not sure about the idling though.
Another car I have didn't start when it was above 68 degrees F before I replaced the crank shaft sensor with quite a length of wire attached to it, which got me thinking about these somewhat heat related issues on my BMW.

I think I will pick up some cable heat shields and test mount those on the wires in front of the engine and see if that helps in any way.

A little off topic:
https://www.carcomplaints.com/news/2...g-wiring.shtml

[PhaseP]

Originally Posted by steifan

Similar issues here with my euro 325i N52B25.

Wall of text:

Noticed when I bought the car in 2014 that the car would often behave strangely when the engine was hot and after driving "normal" with the cruise control engaged the car would "jerk" once and then hesitate when disengaging cruise control and then run week in the lower rpm power band but decent in the upper rpm's, then suddenly it would run "good" with decent low down torque. It didn't bother me much and the car didn't thro...

Yours has the same MAF sensor and so connector as the USA 2006 N52's.
Some of us had problem with the connector not making good connection any more and found fix in this thread. The codes are not matching yours though, maybe the MAF code, not sure what exact one you were receiving.

It may be worth a check, the quickest thing you can do is to remove and then reseat the MAF connector and see if for a few days you are symptom free or not:

https://www.e90post.com/forums/showthread.php?t=1304563

This also can help with your case VANOS issues including cam ledge:

https://static.nhtsa.gov/odi/tsbs/20...32779-8218.pdf

[PhaseP]

Originally Posted by steifan

Another car I have didn't start when it was above 68 degrees F before I replaced the crank shaft sensor with quite a length of wire attached to it, which got me thinking about these somewhat heat related issues on my BMW.[/SIZE]

I had another car in the past (NB Miata), they used to have problem with crank shaft sensor in heat reported by some owners. But in those the sensor was the problem, hitting on it I think was sometimes making it work.

The wires will not change resistance with heat enough to cause any problem. With wires it is usually the connection if there is a problem, or if wire sheath got a puncture and started getting moisture and electryolytes from road salt and grime and then copper rotting out.

[alexwhittemore]

Maybe this is out of left field: bad PCV valve? I don't really know what I'm talking about, so anyone please feel free to jump in -

When I went in to replace the "left" DISA valve, there was quite a bit of oil. I read at the time that "some oil in the intake is normal," but I've since read "but not pooling oil," and it's definitely the case that oil was pooled in there. Pooling oil would, I'm lead to believe, be suggestive of a malfunctioning PCV valve.

An oil-related problem would make a bit of sense, since I seem to be losing oil - for a while, I had a bad valve cover gasket, which got replaced about a year ago. My oil loss seems to be much slower now, but I think last I checked the BC, it was maybe 1/4 or half of the way to "add a quart." When I first got the car, it consumed zero measurable oil for at least a few changes.

A PCV-related problem would also make a bit of sense, in that the problem seems to get worse as the engine warms up. There are a lot of practical reasons it's not noticeable right out of the driveway, but it really feels like it's MUCH worse after 10 or 20m vs on the first hill out of my neighborhood. Maybe it's not bad while the oil is cold and settled.

And further, maybe it's the excessive oil in the intake that CAUSED my DISA valve failure in the first place - oil pooling and coating the rubber gasket material on the valve might have made it just sticky enough to fatigue the plastic gears after a few hot actuations with excess force.

So the question for those of you more knowledgable than I - how does the PCV work and fail, and would failure result in these sort of symptoms?

Also, I'm lead to believe that the PCV valve is now integrated into the valve cover? Was that always the case? Can I replace the valve on its own now or do I have to buy a whole new cover?

[steifan]

Originally Posted by PhaseP

Yours has the same MAF sensor and so connector as the USA 2006 N52's.
Some of us had problem with the connector not making good connection any more and found fix in this thread. The codes are not matching yours though, maybe the MAF code, not sure what exact one you were receiving.

It may be worth a check, the quickest thing you can do is to remove and then reseat the MAF connector and see if for a few days you are symptom free or not:

https://www.e90post.com/forums/showthread.php?t=1304563

This also can help with your case VANOS issues including cam ledge:

https://static.nhtsa.gov/odi/tsbs/20...32779-8218.pdf

Thanks! I got the occasional "Mass or Volume Air flow too high" code a few times when experiencing problems (and some times no code). Haven't seen the code since I replaced the MAF but I didn't always get the code before replacing it either. Will definitely look into replacing the connector parts


Regarding cam ledge I've planned to replace the valve cover gasket so I will check the cam ledge if possible while doing that.

[steifan]

Originally Posted by PhaseP

I had another car in the past (NB Miata), they used to have problem with crank shaft sensor in heat reported by some owners. But in those the sensor was the problem, hitting on it I think was sometimes making it work.

The wires will not change resistance with heat enough to cause any problem. With wires it is usually the connection if there is a problem, or if wire sheath got a puncture and started getting moisture and electryolytes from road salt and grime and then copper rotting out.

Sounds reasonable

[major330i]

I solved the hesitation problem. In my case it is a n53 engine. My fault code storage is empty.. but i feel vibration in idle and the car runs uneven. Hesitation and bucking in lower rpm and i think the car is not as powerful as it should be. Like i wrote before before i changed a lot of parts allready but the problem still persisted. So i bought some diagnosis software (Inpa, ISTA/D) and started to learn how the engine Management of this n53 works. I recommend the website www.bimmerprofs.com -> very deep knowledge. Also you can find links to get diagnosis software and cables for diagnosis.

Then i checked all live data while the engine is running. The voltage of the lambda control probes didn't have the values they should have in idle. They showed 0,18 V while Lamda = 1.00 -> Control probes should create a voltage of 0,7-0,8 V in idle when lamda is 1.00. The lowered voltage of control probes means that there is unburned oxygen in the exhaust. But Lambda is 1.00 so the mixture shows a perfect condition. This means the oxygen seems to get in another way in the exhaust.

In my case an indy deleted my middle cats (nox cats) before all problems began. the problem is that the connection between exhaust manifold and the exhaust strand is not air tight. After the delete the motor adaptions were deleted. If adaptions are deleted the motormanagement starts to relearn everything (fuel adaptions...). Now as i had an exhaust leak right near the control probe (after cat) the calibration of the probe had problems. In such case the msd80/81 (motormanagement in n53) turns off the adaptions and doesn't even try to even the rough run in idle.. all corrections are turned off. The car runs in "limp Mode" (Cylinder work very unbalanced -> live data in inpa "rough run menue" confirms the disbalance). No fault codes are stored!!

Now if you drive in lower rpm and you want suddenly to accelerate but the cylinder are unbalanced such hesitation can happen.

In my case the re-adaption of the engine had problems because of the controle probe but i think in many other cases especially if the car had problems with injectors or nox sensor and the car get new parts but the car still runs like crap -> clear your adaptions and make a re-adaption. If you have no fault codes but your car runs uneven your car might run in limp mode. All you need is INPA and a k+Dcan cable.

[DaanBMW]

So once you diagnosed via SW (BTW, INPA or ISTA ?), then you had looked into the exhaust and found the leak ? And the you just sealed it up, right ? or just reset adaptation (doubt it) ?

...This monitoring is what I' planning next, have to learn what it all means though...

[Saico]

Originally Posted by major330i

I solved the hesitation problem. In my case it is a n53 engine. My fault code storage is empty.. but i feel vibration in idle and the car runs uneven. Hesitation and bucking in lower rpm and i think the car is not as powerful as it should be. Like i wrote before before i changed a lot of parts allready but the problem still persisted. So i bought some diagnosis software (Inpa, ISTA/D) and started to learn how the engine Management of this n53 works. I recommend the website www.bimmerprofs.com -> very deep knowledge. Also you can find links to get diagnosis software and cables for diagnosis.

Then i checked all live data while the engine is running. The voltage of the lambda control probes didn't have the values they should have in idle. They showed 0,18 V while Lamda = 1.00 -> Control probes should create a voltage of 0,7-0,8 V in idle when lamda is 1.00. The lowered voltage of control probes means that there is unburned oxygen in the exhaust. But Lambda is 1.00 so the mixture shows a perfect condition. This means the oxygen seems to get in another way in the exhaust.

In my case an indy deleted my middle cats (nox cats) before all problems began. the problem is that the connection between exhaust manifold and the exhaust strand is not air tight. After the delete the motor adaptions were deleted. If adaptions are deleted the motormanagement starts to relearn everything (fuel adaptions...). Now as i had an exhaust leak right near the control probe (after cat) the calibration of the probe had problems. In such case the msd80/81 (motormanagement in n53) turns off the adaptions and doesn't even try to even the rough run in idle.. all corrections are turned off. The car runs in "limp Mode" (Cylinder work very unbalanced -> live data in inpa "rough run menue" confirms the disbalance). No fault codes are stored!!

Now if you drive in lower rpm and you want suddenly to accelerate but the cylinder are unbalanced such hesitation can happen.

In my case the re-adaption of the engine had problems because of the controle probe but i think in many other cases especially if the car had problems with injectors or nox sensor and the car get new parts but the car still runs like crap -> clear your adaptions and make a re-adaption. If you have no fault codes but your car runs uneven your car might run in limp mode. All you need is INPA and a k+Dcan cable.

I recently had the same issue in N52. I had an exhaust leak right AFTER post-cat probe. Lambda voltage was very low and adaptations were off. It is tricky because adaptations only show 0 in ISTA, there's no fuel trim error code.

After sealing the leak with a new gasket, adaptations started to work, car runs smooth and burns less fuel too.

[major330i]

Exhaust leak confirmed!! Ingas two leaks:

1. Connection between exhaust strand and exhaust manifold
2. One point of the welding (nox cat delete -> straight pipes)

We started the car and sprayed all possible places with soap water and at these two places immediately bubbles appear so air comes out of the exhaust and also sucked.
We fixed these two leaks. I drove the car the whole day without even resetting the adaptions . It’s like a new car wouldn’t have thought that two little leaks in the exhaust can affect the run of the car in such way. No bucking no hesitation in lower rpm anymore. After 1 year changing parts (spend over 5000€ in one year) and now found the cause. Happy as fuck hope I could help some of you maybe it’s the same with your car and it’s easy to check.

[alexwhittemore]

Test drove with an indy today and his thought was motor mounts. Seems like that'd fit, except I'm not sure where the loss of power would come in (but wouldn't rule it out either).

[DaanBMW]

Originally Posted by major330i

Happy as fuck hope I could help some of you maybe it’s the same with your car and it’s easy to check.

Envious... a lot

My research so far is a bit unclear. All was done with INPA.

When driving the car (stepping on gas), as seen in 1st pic, the values seem ok except for that last one which it has no red band triggers an exclamation point "!0.72" in both banks, in what seems to kinda say the adaptation values for the trim adjustment. No idea what that is, but car runs good.

Then when I'm coasting in gear, pic 2, I get a series of values go off the reservation. Lambda values as well as their voltage, before the cats, in both banks are reported off. The values do not have a red band they trespass, but they are reported as "! 3.00", while the voltage does cross well in to red territory. And interestingly, now the previously-off values for that adaptation values for the trim adjustment are now fine.

Trouble is I'm not sure what this all means... can anyone chime in ?
(all other monitors seem ok - lambda, rough running, SAE)

[alexwhittemore]

I haven't yet had the motor mounts looked at, besides by me. (They look fine, but then, I don't know what to look for besides crumbling ruins of rubber.) That said, I don't believe it's them, since the problem seems reproducibly temperature-dependent. Even if failing mounts COULD lead to power loss, the impact for sure wouldn't depend so noticeably on temperature.

I was in, of all places, pep boys, to pick up some injector cleaner just to see. The service advisor asked what was wrong and after talking to the mechanic said "he thinks it sure sounds like low ATF." I started looking for more info about the transmission. Long and short of it, just about every link on the first page of google results for "e90 torque converter shudder" sounds EXACTLY like my problem. I'd never really even considered it because it's a loss of power, I've had engine issues lately, and the transmission has "lifetime fluid." But sure enough, it sounds EXACTLY like what's going on in my car.

I've got an appointment tomorrow morning at a local shop to drain and fill, or perhaps flush depending on the mechanic's opinion. We'll see if it fixes it (or if my transmission is already so worn I can't drive out of the lot with fresh fluid ).

[alexwhittemore]

FWIW, my mechanic said he thinks the fear of changing transmission fluid is WAY overblown, and the only one or two times he's ever seen a fluid flush render a transmission un-drivable, it was already wildly far gone to begin with.

We replaced my differential oil and transmission fluid. My money is on the transmission, since the symptoms seem to match up perfectly with internet anecdotes. His is on the diff, since his interpretation of the symptoms he was able to reproduce matches up with some of his experience with far-gone differential oil.

In any case, the issue sure feels fixed!

We'll see if that holds with a bit more driving, but I'm super duper happy!

EDIT: Follow-up for anyone interested: 7 months later, this was for sure the problem. Hasn't been an issue since. My engine does feel less peppy than it once was, but probably because the car is damn old now

[gavinmanki]

Originally Posted by DaanBMW

did plugs, coils, maf, solenoids, vvt motor, camshaft positioning sensors, vvt check valves. symptoms still there: hesitation/stumbling at starts or low rpms + the rpms drop badly when taken out of gear after coasting, at times killing the engine (with a/c on). puzzled by this beyond belief...

Hi Daan,

My car got the exact problem as yours.
Wanna check out if you have figured out the problem and solved it finally?

Thanks,
Gavin.

[DaanBMW]

Originally Posted by gavinmanki

Hi Daan,

My car got the exact problem as yours.
Wanna check out if you have figured out the problem and solved it finally?

Thanks,
Gavin.

Hi Gavin,

In the meantime I did my last-ditch swap: the fuel pump & filter/regulator (both in tank). So full list is: spark plugs, coils, maf, solenoids, vvt motor, camshaft positioning sensors, vvt check valves, fuel pump ECU, valve cover, ESS (eccentric shaft sensor), fuel pump & filter/regulator.

Result - nothing ! It's as frustrating as it gets.

I'm currently playing around with VVT angle setting thru INPA. While all the ones I tried so far (45 & 135 degrees) are still doing the rpm drop, I want over time to see if one at least avoids killing the engine.

-Dan