N52 hesitation, stuttering, jerking, surging etc

[propaintballa]

What about the valvetronic motor? I’m a newbie on here and my recently bought 2008 z4 2.5si N52 has similar symptoms, it kind of bogs down on initial acceleration and then kind of surges as it moves up through the Rev range until about 3500rpm. If I gently accelerate then I can move through the Rev range smoother. I had fault code for valvetronic adjustment range and knock sensors 1 & 2. Oh and on idle the Rev counter bobbles about slightly. As we speak the dealer I purchased it from is replacing the valvetronic motor. I will let you know if that cures it, I did read about eccentric shaft sensor faults/oil fouling giving similar problems but as I had no fault codes for that I’m hoping it’s just the motor.

Hey, thanks for your reply. I have actually seen a BMW service note (whatever they are called) which talked about a valvetronic motor replacement for similar symptoms if a DME upgrade didn't work, so there could be something to that... However, whilst that sounds similar to my issues, I don't have any codes, the only ones I had was when it died at traffic lights once and wouldn't restart which threw the VANOS solenoid codes. For the record, I don't think many people get eccentric shaft sensor codes, instead it's a case of if there's oil in it, it needs to be replaced along with the gasket/seal. Mine had oil in so replaced it whilst the valve cover gasket was being done.

Do keep me updated about your valvetronic motor though. When are you hoping to have the car back?

[Naylz]

Absolute nightmare, dropped car off last Wednesday, gave him the fault codes and suggested it was the valvetronic motor, after a week of nothing he finally tells me that after trying numerous fixes he now thinks it's the valvetronic motor, he ordered a new one, had a delay removing the old one as he needed to borrow the cam locking tools from another garage, the new motor arrived late only to then be the wrong one. Now he isn't answering his phone or returning my messages, really not happy as this is over a week now and still no idea when it will be sorted or in fact if the motor will truly be the solution. However if I ever get to see my car again I will certainly keep you posted on whether it fixed the issues....#wishingihadntboughtaZ4

[ph001]

Oh dear...I feel your pain. To make matters worse you don’t need to lock the camshaft to change the motor as it is self calibrating. Sorry to say that it sounds like this guy has no idea what he is doing

[Naylz]

Yeah I agree, on my post I was advised to collect my car, however it had already been dismantled.

[propaintballa]

So I was looking around on INPA again, just thought I'd see if there was a VVT re-learn feature or something. Found a test function that sweeps the motor through it's full range, which seemed to be fine. I then thought I'd check out the engine bay as I hadn't since I changed the CCV and DISA and thought, I'll try take the oil cap off to see what happens.

Now, when I used to do this the engine speed didn't change at all, maybe a little if anything and there was what I'd consider a normal amount of suction. Now with the new CCV, the suction seems the same, but the engine tries to die. I cannot remember which one is normal! I am pretty sure what happens now is not normal.

[propaintballa]

Another update. I had all the modules in the car updated to the latest versions (only cost £40 at BMWeymouth if anyone is down that way) and the issue is still present. Because of the mechanical nature of the occurrence of the problem, in that the problem never deviates from the usual RPM range, I am beginning to think something serious is going on here.

My current train of thought is the cam bearing ledge or bearing ledge seals, which would fit in with my previous thoughts about lack of oil pressure affecting timing. This car has been kept to pretty regular service intervals though, so it shouldn't be this, but I am pretty sure it is as I have tried essentially everything else. I really don't know what to do if this is the case, I don't know whether I even want to spend the money to find out if this is the case. Nightmare.

[Capa]

Honestly you have my sympathies on this.

I have a N52k coupe, that just doesn't run... 'right'. No codes. I've just had the coils & plugs replaced, which has improved the issue, but it's still not what it was. 'specialist' garage doesn't really seem to have a clue, and I'm loath to ditch more money into it with them.

Currently I'm just living with it. Though I might invest some time over easter to try some of the above.

[propaintballa]

Honestly you have my sympathies on this.

I have a N52k coupe, that just doesn't run... 'right'. No codes. I've just had the coils & plugs replaced, which has improved the issue, but it's still not what it was. 'specialist' garage doesn't really seem to have a clue, and I'm loath to ditch more money into it with them.

Currently I'm just living with it. Though I might invest some time over easter to try some of the above.

As much as I wouldn't want to wish this on anyone, it's nice to know I'm not the only one, especially when garages don't seem to detect problems! At least your car is probably worth saving when compared to mine, I don't feel like mine is in a condition I'd be happy selling it in just to get rid either!

What are your symptoms out of interest?

[Capa]

It's a real pain, and it's kinda sapping my enjoyment out of the car. I've left it alone for a couple of months in the hope that it'll eventually manifest itself in a fault code, but nothing as of yet. I'm still looking to save it at present, but I think everyone's patience (and pockets) have their limits.

It's got 108 on the clock, and to me, there's a 'roughness' coming through the accelerator pedal. Almost a bit like a wheel bearing feels when it's had enough. It doesn't seem to idle right either, and occasionally the pick-up/response goes awry. It's not noticeable to passengers, but knowing how smooth the engine can be, I feel the fact it's off.

In terms of what I've tried:

* New plugs - tried Bosch/NGK. The latter under advisement from the specialist. The old plugs were pretty merked and needed doing, but no real discernable difference to the running of the motor
* Compression test - engine is fine, all is well at 8+
* Smoke test - apparently, there is a "very very small" leak, that isn't having an effect on anything. (more on this later)
* New coils - made some improvement for sure. I'm not happy with the end result however - nor was I particularly amused at the fact the 'specialist' essentially threw new coils & plugs at it and pretty much said good luck.
* Tested each of the injectors with a spare - no difference. They're just as ticky as each other!
* Cleaned both the VANOS solenoids
* Had a look at the DISA valve - interestingly, I don't have oil in the intake to the levels you've described.

In terms of what I think is wrong:
* Under ph001's advisement I checked the battery today. It's sat at 12.28v - and looking at the date stamp, is the original unit that shipped with the car (honestly, an 11 year old battery that still can turn a car on? Almost unheard of...) But either way, he'll be going in the bin with a replacement on its way soon.
* I am highly suspicious of this 'very very small' air leak. A while ago I saw an o2 sensor fuel trim fault code (it's not come back since), so I'd be keen to get my mitts on a smoke tester at some point and dig further into it.
* o2 sensors. I'm suspicious of these because of some of the above posts, and because the car smells a bit fuelly. Replacing all of them is a pain in the arse and a substantial financial hit.
* Beyond that I've got ideas like the CCV being gummed up, a bad earth or wiring fault somewhere in the circuit that's driving the coils, a knackered fuel pump, leprechauns etc. but they're nothing more than ideas based off hunches with naff all to back them up.

I'm not super hopeful with any of the above really, but we'll have to see.

[propaintballa]

It's a real pain, and it's kinda sapping my enjoyment out of the car. I've left it alone for a couple of months in the hope that it'll eventually manifest itself in a fault code, but nothing as of yet. I'm still looking to save it at present, but I think everyone's patience (and pockets) have their limits.

It's got 108 on the clock, and to me, there's a 'roughness' coming through the accelerator pedal. Almost a bit like a wheel bearing feels when it's had enough. It doesn't seem to idle right either, and occasionally the pick-up/response goes awry. It's not noticeable to passengers, but knowing how smooth the engine can be, I feel the fact it's off.

In terms of what I've tried:

* New plugs - tried Bosch/NGK. The latter under advisement from the specialist. The old plugs were pretty merked and needed doing, but no real discernable difference to the running of the motor
* Compression test - engine is fine, all is well at 8+
* Smoke test - apparently, there is a "very very small" leak, that isn't having an effect on anything. (more on this later)
* New coils - made some improvement for sure. I'm not happy with the end result however - nor was I particularly amused at the fact the 'specialist' essentially threw new coils & plugs at it and pretty much said good luck.
* Tested each of the injectors with a spare - no difference. They're just as ticky as each other!
* Cleaned both the VANOS solenoids
* Had a look at the DISA valve - interestingly, I don't have oil in the intake to the levels you've described.

In terms of what I think is wrong:
* Under ph001's advisement I checked the battery today. It's sat at 12.28v - and looking at the date stamp, is the original unit that shipped with the car (honestly, an 11 year old battery that still can turn a car on? Almost unheard of...) But either way, he'll be going in the bin with a replacement on its way soon.
* I am highly suspicious of this 'very very small' air leak. A while ago I saw an o2 sensor fuel trim fault code (it's not come back since), so I'd be keen to get my mitts on a smoke tester at some point and dig further into it.
* o2 sensors. I'm suspicious of these because of some of the above posts, and because the car smells a bit fuelly. Replacing all of them is a pain in the arse and a substantial financial hit.
* Beyond that I've got ideas like the CCV being gummed up, a bad earth or wiring fault somewhere in the circuit that's driving the coils, a knackered fuel pump, leprechauns etc. but they're nothing more than ideas based off hunches with naff all to back them up.

I'm not super hopeful with any of the above really, but we'll have to see.

I get exactly what you mean with niggles ruining the overall enjoyment of the car. I actually experienced the same kind of thing with a Z4C I bought (and subsequently returned after a court case), except the engine was sweet.

Interesting. The pickup issue could definitely be caused by the things I have replaced on mine. In your position, I'd be inclined check the eccentric shaft sensor for oil. This is easy to do and can be found on the front/top of your engine underneath the plastic cover. If there is oil in it, it needs to be replaced along with the seal. This is a valve cover off job. I'd be inclined to replace the valve cover gasket at the same time as the parts are relatively cheap and if it hasn't been done already, it will surely fail imminently. Next simple job would be to check and clean the MAF with some MAF cleaner.

Moving on, I think you should tackle the CCV. At your mileage it almost certainly needs to be replaced and can fail in various ways that don't necessarily mean it puts oil into the intake like mine did. Whilst doing that is the best time to check the inner DISA valve and pray it's okay, because the genuine part is bloody extortionate.

The problem is that it's a slippery slope, so if you're anything like me, the sunk cost element has forced me to a point where I feel like I have spent more than I should have and now need to find the actual issue. In the beginning, I was convinced the first few fixes would remedy the problem. Boy, was I wrong!

If this has taught me anything it's that if I was at your stage again, I'd probably sell the car. If you want to find the problem, be sure you want to keep it, because you could very well be looking at something really serious and expensive a few months down the line!

[juld0zer]

I have a 130i that is doing the same thing.
I noticed in the Valvetronic screenshot in INPA that your long term (multiplicative) fuel trims on both banks are at -7%. So are mine. That is a really high amount of correction for a too rich condition and being on both banks suggests a global level problem rather than an issue with a particular bank.

I have a new tank vent valve/purge control solenoid valve coming next week. In the interim, i have blanked off the valve and done a battery reset. It still feels flat, which is disappointing but we'll see when the new valve arrives and i will reset the DME adaptations with ISTA/D.

I have done the following:
Valve cover gasket (leaking)
Eccentric shaft sensor with a VDO part (oil leaking through the pins)
New NGK platinum plugs
Donor set of 6 coils (late version Bosch with the non clicking end fitting)
Both VANOS solenoids with genuine parts
Both check valves/VANOS filters with genuine parts
Two oil changes with genuine filter and LL01 oil
New air filter
New battery

I am also suspecting the valvetronic motor due to age and heat. I also noticed quite a lot of wear on the eccentric shaft gear however, live data in INPA indicates a very healthy valvetronic system and VANOS system

[juld0zer]

I might also need to pull the cowl cover off to get a proper view of spark plug bore 5 because i seem to remember it didnt give much coil to plug engagement feedback no matter what i tried.
I don't have any rough running or misfires logged like the rest of you though, unless it occurs under load as i have only checked it at idle while stationary

[propaintballa]

I have a 130i that is doing the same thing.
I noticed in the Valvetronic screenshot in INPA that your long term (multiplicative) fuel trims on both banks are at -7%. So are mine. That is a really high amount of correction for a too rich condition and being on both banks suggests a global level problem rather than an issue with a particular bank.

I have a new tank vent valve/purge control solenoid valve coming next week. In the interim, i have blanked off the valve and done a battery reset. It still feels flat, which is disappointing but we'll see when the new valve arrives and i will reset the DME adaptations with ISTA/D.

I have done the following:
Valve cover gasket (leaking)
Eccentric shaft sensor with a VDO part (oil leaking through the pins)
New NGK platinum plugs
Donor set of 6 coils (late version Bosch with the non clicking end fitting)
Both VANOS solenoids with genuine parts
Both check valves/VANOS filters with genuine parts
Two oil changes with genuine filter and LL01 oil
New air filter
New battery

I am also suspecting the valvetronic motor due to age and heat. I also noticed quite a lot of wear on the eccentric shaft gear however, live data in INPA indicates a very healthy valvetronic system and VANOS system

Sorry to hear you're in the same boat. What do you think is causing the rich condition? Something to do with 02 sensors maybe, or do you think it's connected to your tank vent valve? If not, why have you suspected the tank vent valve?

Yesterday I put my old MAF back in and reset the adaptions, just out of interest and the car seems to feel a lot better, though the rough idle is still there. One of two things are happening here. 1) the MAF I replaced the old one with is faulty. 2) it's running better because there are no adaptions and it's running off stock parameters. If this is the case, I will expect to find the car gradually starting to perform badly again. I think the latter scenario is more probable, and would then point to something controlling the mixture I guess? Maybe )2 sensors, knock sensor or something like that. Though again, I have no codes and I gather there are usually codes present regarding mixture (lean/rich) in the instance those parts fail...

I'm just stumped!

[juld0zer]

I am suspecting the tank vent valve because it was idling rough and felt rough accelerating below 2200rpm even in neutral. I was watching live data on INPA for about an hour while this was happening then all of a sudden the roughness stopped and the only thing that stood out was the tank vent valve duty cycle changed to zero. It was about 45% before. So i suspected the valve or something downstream of it was causing an issue. Perhaps intermittently stuck open, draining the charcoal canister of combustible fumes so there was nothing left when the valve was commanded open, thus drawing in air and running rough?

I've done many adaptations resets and it always deteriorates after a few weeks so I wouldn't hold my breath. It is good practice to reset adaptations when changing major components like a MAF or fixing a miss. I've never had relevant codes either. It seems this DME is quite forgiving. I even had the VANOS solenoids connected backwards and drove for 15km with no CEL. It just felt flat down low and revved up to 1500rpm when i pressed the clutch in

I swapped cyl 5 coil to cyl 2 and reseated the rest with a rocking/twisting motion to ensure any stubborn seals don't push the coil up. The coil that was from cyl 5 was noticeably more 'springy' than the others and would push itself up 3-4mm after being pressed down. I had to rock it a lot until it finally relaxed and no longer sprung up. It seems the later Bosch coils don't have the click tab which attaches to the top plug terminal. They changed to a wrap around coil/spring connector and now rely on the rubber boot and the rubber lips at the top to hold the coil in place. I suspect the rubber lips on #5 coil were unusually stubborn

[propaintballa]

I am suspecting the tank vent valve because it was idling rough and felt rough accelerating below 2200rpm even in neutral. I was watching live data on INPA for about an hour while this was happening then all of a sudden the roughness stopped and the only thing that stood out was the tank vent valve duty cycle changed to zero. It was about 45% before. So i suspected the valve or something downstream of it was causing an issue. Perhaps intermittently stuck open, draining the charcoal canister of combustible fumes so there was nothing left when the valve was commanded open, thus drawing in air and running rough?

I've done many adaptations resets and it always deteriorates after a few weeks so I wouldn't hold my breath. It is good practice to reset adaptations when changing major components like a MAF or fixing a miss. I've never had relevant codes either. It seems this DME is quite forgiving. I even had the VANOS solenoids connected backwards and drove for 15km with no CEL. It just felt flat down low and revved up to 1500rpm when i pressed the clutch in

I swapped cyl 5 coil to cyl 2 and reseated the rest with a rocking/twisting motion to ensure any stubborn seals don't push the coil up. The coil that was from cyl 5 was noticeably more 'springy' than the others and would push itself up 3-4mm after being pressed down. I had to rock it a lot until it finally relaxed and no longer sprung up. It seems the later Bosch coils don't have the click tab which attaches to the top plug terminal. They changed to a wrap around coil/spring connector and now rely on the rubber boot and the rubber lips at the top to hold the coil in place. I suspect the rubber lips on #5 coil were unusually stubborn

I see, that sounds a bit different to mine. Although I have rough idle, it doesn't seem to affect revving the car whilst it's in neutral. I have to admit, as familiar as I am with these engines now, I'm not very clued up on the fuel venting system, so I couldn't speculate, but keep us updated for sure!

Very odd what you report with your cyl 5 coil. Again, not really sure what could cause that. I am away at the moment, but I took a video the other day of the rattle/knock that is present on my car. When I used to notice it, i thought it was the inner DISA valve rattling, but upon further listening, I think it's coming from around the cyl5 area, which makes me think it's a stuck lifter or damaged valve or something similar.