N52 hesitation, stuttering, jerking, surging etc

[propaintballa]

Doh! Just seen plugs,sorry

Haha, no worries. Your thoughts on the current plugs?

[jack07]

Mingers! I go for the platinum NGKS,and replace before the mileage,never get trouble,and checks all 6 cylinders colours .The really dear ones stay in far too long,so you don't get to check in between.

[propaintballa]

Hi, I found when my si started to use oil it was fouling the plugs closest to the bulkhead the most which I presume is linked to the position the ccv is plumbed into the inlet manifold?
Rob

Oh right, was there an actual issue in the end? Blocked CCV or similar? I'll have to check my oil level to see if it is actually using oil.
[/quote]

I blamed a partially blocked ccv system as after flushing it through with sea foam several times matters improved to normal levels.
Rob
[/quote]

Interesting. Do you have any info on how this can be done? I've noticed quite a bit of oil usage, bearing in mind i only changed the oil about 1000 miles ago, which combined with the oil in the intake, would suggest an issue with the CCV...

[Smartbear]

Hi, I found when my si started to use oil it was fouling the plugs closest to the bulkhead the most which I presume is linked to the position the ccv is plumbed into the inlet manifold?
Rob

Oh right, was there an actual issue in the end? Blocked CCV or similar? I'll have to check my oil level to see if it is actually using oil.

I blamed a partially blocked ccv system as after flushing it through with sea foam several times matters improved to normal levels.
Rob
[/quote]

Interesting. Do you have any info on how this can be done? I've noticed quite a bit of oil usage, bearing in mind i only changed the oil about 1000 miles ago, which combined with the oil in the intake, would suggest an issue with the CCV...
[/quote]

Hi, I just put a load down the top pipe with a large syringe & blew down the lower section until I could hear the oil bubbling in the sump!
I did this several times and ran the car until it was hot and changed the oil
Rob

[propaintballa]

Dammit, I've only just changed the oil -.- haha

[propaintballa]

Quick update: So I replaced the plugs with some NGK Iridiums and the issue still persists. Getting a bit fed up of throwing money at it at the moment, so just going to leave it for now. Could be CCV, I don't know :/

[AveZ4coop]

I am sure you have checked, but make sure all the coil packs are seated all the way down on the plugs. I found the newer type coil packs did not seat as well as the old 'click' type. Wiggled mine all the way down and problem went away.

Long shot, but worth looking at?

[ph001]

Don't give up - you haven't even got to any of the expensive bits yet! You said you had a lot of oil in the intake, increased oil consumption and plug fouling. Sounds like no.4 on the list is almost obligatory...

1) Observe O2 sensor voltages in INPA
2) Fit new battery
3) Replace coil packs and plugs
4) Replace CCV valve and check pipes to sump for blockages
5) Replace / inspect second DISA valve
6) Replace valvetronic motor
7) Have VANOS unit stripped and inspected.

[propaintballa]

I am sure you have checked, but make sure all the coil packs are seated all the way down on the plugs. I found the newer type coil packs did not seat as well as the old 'click' type. Wiggled mine all the way down and problem went away.

Long shot, but worth looking at?

.

I actually bought the 'old' type, assuming by that you mean the Bosch coils as opposed to the Delphi replacements? Thanks though, I will double check although I feel like I was pretty positive in my hammering them in in anger at the time

Don't give up - you haven't even got to any of the expensive bits yet! You said you had a lot of oil in the intake, increased oil consumption and plug fouling. Sounds like no.4 on the list is almost obligatory...

1) Observe O2 sensor voltages in INPA
2) Fit new battery
3) Replace coil packs and plugs
4) Replace CCV valve and check pipes to sump for blockages
5) Replace / inspect second DISA valve
6) Replace valvetronic motor
7) Have VANOS unit stripped and inspected.

That's not true! I've done MAF, 2 VANOS solenoids, eccentric shaft sensor and VCG! The latter of which isn't THAT expensive but I think the rest is, especially considering the monetary value of the car. I think I'll have to wait until after Christmas as we have a holiday to Barbados to pay for and a house we are renovating (problems happen at the worst times!).

After that, I think I will get that lower DISA out and have a look. There is a slight rattle in the engine bay which is hard to trace, but could be that. Then I think CCV. That is if I haven't just sold it by then. Though I suppose whilst inspecting the DISA, may as well do the CCV as the intake has to come off -.-

Another thing I read about actually, was someone with the same symptoms caused by the valvetronic motor gasket leaking. Which I feel would be obvious to the ear, but I might check that out. Unsure if the VCG kit comes with that gasket.

[propaintballa]

Okay so quick update, if this counts as one, other than my bloody sunroof now randomly opening, I have stumbled upon a new bit of info from my OBD reader.

Within the "smooth running" live data, cylinder 5 appears to be running waaayyyyy out of the parameters listed (-200 to 200). -200 to 200 what exactly, I am not sure, but the values seemed to peak at ~-3000 (picture below). The rest seem to be around (-)50, +-50 or so.

Seeing as I have replaced coils and plugs within the last couple of months, my thoughts are now with the injector. Of course it could still be anything, could be valve or cylinder related, however I find the latter options highly unlikely... Any thoughts on the likelihood of an injector problem? When I have time, I could try swapping injector positions and see if the rough running follows.

The only problem I have with this diagnosis is that I have listened to the injectors for the solenoid function and they all seem the same to activate consistently and with the same volume. I have Also tried injector cleaner since I've had this problem which hasn't done anything (surprise).

[ph001]

Doesn’t seem to concur with the rough running data on that cyl in INPA though.

Your reluctance to inspect the Ccv system seems illogical.

[propaintballa]

Doesn’t seem to concur with the rough running data on that cyl in INPA though.

Your reluctance to inspect the Ccv system seems illogical.

That's true, I forgot about the INPA stuff. Oh, my reluctance is probably because an injector is a lot easier to fix Hahah

On a serious note though, I don't suspect one more than the other, there are aspects of both that make me question them. For example, from what I gather, CCV issues seem to cause excessive oil filler cap vacuum if they are blocked. But I guess it doesn't rule out a leak, though the vacuum at the oil filler cap seems normal (based on the Z4C I had).

[ph001]

It's really based on the 2+ years I have been on here I have never heard of a single E85 / E86 injector problem (in stark contrast to the E89 N54 with it's piezo injectors). That's not to say it's not possible of course but if you have no error codes to go on you have to start with the most likely / least expensive culprits first.

CCV problems are fairly widespread, moreso on the M54B30 admittedly but still quite a few on the N52. It wasn't until the later revised N52K system that BMW seem to have got their heads around it.

[propaintballa]

So just to update this. I finally got around to doing the CCV, replaced the actual unit and the associated breather hoses. I had a feeling I might find other issues whilst I was doing this, so it came as no surprise when I found the internal rubber seals on the inner DISA valve to have disintegrated. That being said, I was expecting the flap to be loose due to a rattle noise the car makes at idle.

Is it fixed? In short, no. The work I did has remedied some ill behaviours, but not all of them. The random stuttering and bucking at certain points in the rev range when going at constant speed is still there, as is the rough idle and just general abnormal power delivery.

What have I replaced so far?

MAF
Valve cover gasket
Oil and filter
Eccentric shaft sensor
Both VANOS solenoids
Spark plugs
Ignition coils
CCV
Inner DISA

I am just lost now. Part of me thinks there is a timing issue issue that is either down to the mechanical timing or oil pressure related which is affecting the valvetronic/VANOS. The rattle which is sometimes audible at idle makes me think there could be a more sinister reason for this. I think the only other 'simple' thing I haven't tried which I have seen as a fix for similar symptoms was replacing the VANOS non-return valves. Like mine, the guy mentioned they looked fine (I cleaned mine) but the new ones resolved his hesitation issue. He determined this was as a result of the spring/moving part malfunctioning despite it looking fine.

[Naylz]

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.