[rjshuttleworth]

Hi All

This is my first post having found these forums to be incredibly valuable. I am looking to gather some opinion on a rather annoying fault I have. Let me start with the issue:

Issue:

Intermittent, pronounced loss of power on acceleration. Causing risk of accident as loss unexpected and often occurs at critical driving moments.

Normally when slow rolling at roundabout/junction and apply moderate throttle to accelerate into a gap. Engine feels like it will stall or will kangeroo/jerk quite violently for as long as the accelerator is pressed or for a few seconds. Let off accelerator and reapply and engine accelerates normally.

Can recreate if put in N and then R and accelerate briskly. Engine will likely stall.

Also in N or P and blip the throttle it will stutter as if lack of fuel or air then accelerate freely. Can stall when doing this too.

Easier to recreate when engine is hot. No engine lights are coming on when fault happens, even after stall or violent kangerooing on acceleration.

Work done to try and resolve:

Home scanner showed a 2A98 fault so cleaned Vanos Solenoids and replaced Inlet Cam Position Sensor. No change, so moved old inlet CPS to exhaust CPS position. No change.

Disconnected Inlet Vanos Solenoid and issue disappears albeit performance of car impacted. So replaced both Vanos Solenoids. Car performs better, but has not resolved issue at all.

Suspect it is something related to Vanos system, crank sensor, eccentric shaft sensor or similar rather than coils/ignition related, as when you disconnect the solenoids (and presumably disable the VVT system) the problem disappears.

Took to Dealer for diagnostics

No faults in dealer tooling.

No software updates for the ECU or Gearbox are available.

Dealer recommends checking timing which is 4hours labour. It didn't think this was a reasonable 'speculative check' so I brought the car home instead of letting them take the valve cover off and dig around.

Should say: Car is N52B30A engine, e91 330i auto, 61k miles. I've read hundreds of posts related to this and not sure I've found a definitive resolution

Question for the knowledgeable on the forums: Would my assessment that if the vanos system is disconnected (and BMWs suspicion that the valve timing is off enough that vanos is correcting but causing issues, but not enough to throw faults is correct) then the problem should be more pronounced as no VVT to correct for a problem?

I have a feeling it's the eccentric shaft sensor from other threads (the idle is fine, and it starts fine, so doubtful it's the crank position sensor) and i've ruled out Vanos solenoids.

So I investigated further and their was slight oil in the connector (not a lot, just a little). I completely cleaned with contact cleaner, dried, and then reconnected and ran engine for 5 mins. A slight oiling returned. So to test I disconnected the sensor and the symptoms go aswell.

So, BIG question is what is the relation between VANOS and Valvetronic? Seems disabling one or the other kills my problem.

Any thoughts from the gurus?

R

I would start by replacing/cleaning your vanos solenoids, camshaft sensor, and then the eccentric shaft sensor. Also clean your maf sensor. It could be anything but try those.

[sirantsE90]

Agreed, sounds like a bad MAF sensor. Just spray with cleaner or pick up a new one.

[rjshuttleworth]

Thanks for the replies.

I've cleaned MAF with contact cleaner and there was no change.

I've replaced both solenoids with new parts.

I've replaced the inlet camshaft sensor with new, no change, so swapped the old inlet for the exhaust camshaft sensor, and again no change.

I am guessing it's the eccentric shaft sensor, rather than the crankshaft sensor.

Just frustrating that there are no fault codes!

Another symptom I noticed this morning when starting it from cold, the idle was erratic, jumping up and down maybe 300rpm at a about 1sec frequency before settling down.

I suppose if it is the eccentric shaft sensor it will get progressively worse as more oil gets into it.

But do you all agree that the stealer was shooting the dark by wanting to check the timing as 'it could have jumped a tooth'...? Sounds pretty unlikely to me. They also said that there was a crankshaft bolt that can come loose causing the timing to go out. Again, I couldnt get a straight answer on that one, as when I asked how they'd tighten the bolt by just lifting the cam shaft cover they gave me a load of BS....

thanks again all...

[rjshuttleworth]

Another update:

I unplugged the MAF today and ran on default settings. This cured the problem too but I am suspicious that this is not the cause.

Basically unplugging anything (vanos solenoids, eccentric shaft, MAF) gets rid of the problem, but each has differing side effects on the power/drivability.

I am on a big run tomorrow and it *always* plays up at the end when parking up at the office. So, I will run with MAF in, Vanos connected, and just disable the Valvetronic. I should witness no problems at the end. I've also recleaned the Eccentric Shaft Sensor socket and it is completely oil free. So theory goes that it should have oil in it at the end of the journey showing it is knackered.

Question: Would you buy a replacement sensor from a breaker? Or go new? Breaker is a £100 vs new at £320. Am going to do the job myself if I do it at all...

[DaanBMW]

Originally Posted by rjshuttleworth

I've cleaned MAF with contact cleaner and there was no change.

I also suspecting your MAF. Did you clean the sensor & the connector ? If not, both should be cleaned with non-residue cleaner.

[rjshuttleworth]

Yeah, cleaned the MAF as you say.

The thing is, with the MAF connected, and the eccentric shaft connector Disconnected, problem is gone.

If it were the MAF i would have thought this would not solve it....

[rjshuttleworth]

What a crapper. Somebody decided to have a momentary lapse of reason and ...

Crunch

[rjshuttleworth]

really gutted.

only engine i've wanted to DIY on since my Dad's Kawasaki Z1 :-(

and now it's crunched.....

[rjshuttleworth]

boooooo

good night

[petelazro]

i have been having this same problem for almost 6months now. I have the RPM jumping 100-200 on start up with the car shaking. dealer is not seeing any codes. I also noticed that on colder days my car drive much better compared to warmer days. there is a huge lag in power on hot days.

hot day 22C or more
cold day 18C or less

its a night and day difference which my passengers can feel. throttle response is a night and day difference as well.

dealer said it could be a leaky injector thats not throwing a code but they wont change it under CPO unless it throws a code.

im glad winter is coming so my car drives better. summer really killed it for me.

[rjshuttleworth]

Have you tried disconnecting your eccentric shaft sensor from the top front of the engine? It's under the plastic engine cover (which pops out easily if the engine is warm as the rubber grommets soften).

From other threads (there's a DIY on replacing the sensor you can easily find) it is apparent that if there is oil in the socket the sensor is hosed. I am guessing that the oil on hot/warm days is thinner and more likley to create electrical madness at the leaky sensor (which should have no oil in it)

I disconnected the sensor and the car is back to being a beast (although shifts are rougher) as the variable valve lift is disabled and the throttle is controlled by a traditional system as a fall back.

Try it and see if that resolves your issue assuming you have some oil in your connector socket. At least then you'll have something to say to the dealer.

My dealer said the timing chain had jumped a tooth so I wont be going back to them! Master Technician my butt!

[petelazro]

okay i will try that this weekend. im really hoping it works. would this be covered under CPO if it was the shaft?

[MikeR1994]

I also have this issue. I had the wires for my B2S1 o2 sensor on the engine wiring harness short out, and I rewired it 3 times thinking that I hadn't done it properly and that it was running on some sort of failsafe map. Maybe I'm not as bad with wiring as I thought?

[rjshuttleworth]

Originally Posted by petelazro

okay i will try that this weekend. im really hoping it works. would this be covered under CPO if it was the shaft?

I doubt the shaft itself is anything to worry about. It's not the camshaft or anything, its a shaft that turns about 90 degrees via a motor to vary the lift of the valves. The sensor is at the end of the shaft and provides feedback on what position it is in. This all acts as a throttle too. When you disconnect the sensor the system fails back to default valve lift and a different more traditional throttle control.

I've seen threads where the sensor replacement was covered, but the challenge is no codes being thrown and convinciung a mechanic that this is what is wrong. Some seem to have seen it a dozen times, others wont breath without a code, let alone lift the valve cover...

Post back when you've run it disconnected...

[rjshuttleworth]

Release date (dd/mm/yy)
30/09/09
Status
Approved
Organization
GB, CAR
Vehicles affected
E series
E60 E61 E63 E64 E90
E91 E92
Engine
N52 N52BO0 N52K
Body

Production period (from/to) (dd/mm/yy)
/
Comment on production period

Feedback (all cases relating to measure up to) (dd/mm/yy)

Complaint
An intermittent hesitation or flat spot when accelerating is felt briefly under different driving conditions
such as:
Pulling away from stationary
After a coasting phase
When overtaking

This complaint appears over a period of time and gets progressively worse.
Cause
Combination of adaptive values and an early I-Stage or sluggish VVT motor

No fault codes are recorded in the DME (or EGS)
Measure
After confirming the customer complaint and under which driving condition the problem is most obvious,
carry out the following work in the specific order:

Step 1
1. Program the vehicle with ISTA/P 2.35.1 or higher

2. Clear the DME adaptive values using the diagnosis service function.
3. Switch on the ignition and leave for at least 30 seconds to allow the DK unit adaptation to be carried
out - this can usually be heard.
4. Start the engine and allow to idle up to an engine temperature of at least 70°C with no consumers
switched on
5. With ISTA/D or the GT1 learn the VVT end stops
6. Allow the engine to idle for 3 minutes with the vehicle stationary, the transmission in Park and the
steering centred (NO consumers switched on).
7. Then with the engine at idle and the car stationary, select Drive, switch on the Air Conditioning and
then turn the steering to full left lock and then to full right lock twice in succession.
8. Now drive the vehicle forwards and backwards approximately 5 metres to permit transmission
adaptation.
9. Then with the car on a road test drive at a steady 50 - 65 km/h for at least 10 minutes using M2 or
M3; then accelerate moderately in 2nd or 3rd gear up to 4000 rpm and decelerate by letting the car roll
until reaching engine idle speed; then stop and let engine run at idle speed for 5 minutes, do this two or
three times
10. Check the DME statuses to ensure the additive and multiplicative values are OK.
11. Run the engine at idling speed for at least 5 minutes again

Now re-evaluate the car for the customer complaint, if the hesitation is no longer present no further
action is required.

If the hesitation is still present then carry out step 2

Step 2
Replace the VVT motor

[DaanBMW]

^ So for manuals directly replace the VVT motor ? Don't think there's any adaptive anything for manual trannys...

[AlpineSwift]

Might have been addressed earlier but have you checked the battery to see if you have a dead cell?

I encountered a similar problem with mine earlier this year that resulted in continual limp mode until I got into the dealer. Found a dead and completely corroded battery/main wiring harness after a thorough inspection. Set me back about $3000.

[e90pilot]

It mentions "DK" adaptations. Not sure what that means. I'm also wondering how to set VVT limits with a BT tools. You can reset it but I'm not sue you to set the limits.

[Fuji]

Originally Posted by petelazro

i have been having this same problem for almost 6months now. I have the RPM jumping 100-200 on start up with the car shaking. dealer is not seeing any codes. I also noticed that on colder days my car drive much better compared to warmer days. there is a huge lag in power on hot days.

hot day 22C or more
cold day 18C or less

its a night and day difference which my passengers can feel. throttle response is a night and day difference as well.

dealer said it could be a leaky injector thats not throwing a code but they wont change it under CPO unless it throws a code.

im glad winter is coming so my car drives better. summer really killed it for me.

I know this is a really old thread, however I believe I have similar symptoms to you! Did you ever manage to get your cold starts sorted?

Thanks

[neyshule]

did you finally solve your problem?

[Fuji]

Originally Posted by neyshule

did you finally solve your problem?

Unfortunately still got it 😭 I'm taking it in next week for them to further diagnose!