N52 hesitation, stuttering, jerking, surging etc

[ph001]

Any news on the lambda sensors OP?

[propaintballa]

Any news on the lambda sensors OP?

Hey,

Sorry for the slow reply. Fitted the new o2 sensors but very soon after had a rear tyre fail, so had to get a full set, which really stung, and as such, couldn't really bring myself to talk about car stuff. Anyway, new set on and classic issues with alignment, the car is running pretty well. I'd say the surging and hesitation is gone for the most part. Power is notably better with much better pull from low down in the revs. So on that front, I've made progress, but naturally, there are still remnants of the issue.

I still have this hunting idle, which admittedly doesn't happen every time I come to an idle, but I'd say 70% of the time it does. This is paired with that weird rev behaviour where if I rev the car from idle, the revs drop momentarily, then increase as you'd expect. I've been meaning to give my MAP sensor a clean, as I obviously used to have a lot of oil in the intake and when I had the intake off, I had it at all kinds of random angles to prevent oil spilling out. There is a chance that is fouled, but that's just a stab in the dark and something to do that doesn't cost anything.

I thought more about the engine behaviour if I open the oil filler cap with it running. Prior to changing the CCV, opening the filler cap didn't change engine behaviour. Since changing the CCV, the engine tries to stall. I saw a video today in fact, that suggested this kind of behaviour points to a bad CCV (PCV in the case of the video). Now I don't know whether mine was/is defective. I guess it's still a possible cause sadly.

Overall the car is running pretty well, to the point where I think I'm now happy with it. It's not perfect, but it is significantly better than when I started this thread.

[propaintballa]

Another quick update. I cleaned the MAP sensor last night and it did appear to have an amount of oil in it, how much I am not sure. What can I say, I am pretty sure the hesitation is 95% gone. I've done a number of 3rd gear pulls from 1000rpm which is when I could feel it most and it feels a lot better. I am yet to do a higher gear pull which is when the problem is more obvious.

I still have the hunting idle, so I am not sure what that is. I may have to do another adaption reset as the MAP sensor obviously has a pretty big influence on the closed-loop running of the car. Overall, I think this is it. I'm not throwing any more money at the problem!

[Our03z4]

This is interesting to read since I've been having the exact same problem since June with my 08 Z4C 3.0si.
I've had it to BMW multiple times with no issues found at all. Mine has the autobox so they changed the fluid, pan, and rubber sleeves at the tune of 900usd. No dice. Changed the coils, plugs, cleaned the maf, and nothing helped.
Only thing I found that helps is when it acts up run it as hard as possible. I'm talking red line, hard as possible take offs and such. Usually goes away for say 300 miles. Love the car but it just ruins the experience. Also sometimes it will make the strangest noise when accelerating, like a horn kind of sound. Only does this when having the other issue. Sounds like its right under the seat so I'm thinking the noise is coming out the exhaust.
I've really just gotten use to it at this point and have no problem driving it 400+ miles at a time. Mine has 89k miles. Oh and I've also found that it only messes up below 3k rpms, maybe one of the Disa valves? Valvetronic motor? Sometimes I'll just keep it above 3k to stay away from the feeling.

[propaintballa]

This is interesting to read since I've been having the exact same problem since June with my 08 Z4C 3.0si.
I've had it to BMW multiple times with no issues found at all. Mine has the autobox so they changed the fluid, pan, and rubber sleeves at the tune of 900usd. No dice. Changed the coils, plugs, cleaned the maf, and nothing helped.
Only thing I found that helps is when it acts up run it as hard as possible. I'm talking red line, hard as possible take offs and such. Usually goes away for say 300 miles. Love the car but it just ruins the experience. Also sometimes it will make the strangest noise when accelerating, like a horn kind of sound. Only does this when having the other issue. Sounds like its right under the seat so I'm thinking the noise is coming out the exhaust.
I've really just gotten use to it at this point and have no problem driving it 400+ miles at a time. Mine has 89k miles. Oh and I've also found that it only messes up below 3k rpms, maybe one of the Disa valves? Valvetronic motor? Sometimes I'll just keep it above 3k to stay away from the feeling.

Sorry to hear you're having the same kind of problems. I wouldn't wish this kind of turmoil on anyone! Interestingly, "Capa" on here had a similar problem with what he described as a 'whooshing' noise. He took it to a garage and they seemed to think it was a heatshield, which I found to be a strange diagnosis. I believe he ended up changing a DISA valve which was damaged, but didn't make a difference.

What I have learnt is that these problems don't seem to have a singular cause, it's usually a few issues interacting with eachother. What I have also realised is that the VANOS solenoids are basically a service item. So if your car is around 100k miles and on the original solenoids, I'd be willing to bet they need to be replaced. I used to have a really strange power surge after 3k RPM which replacement of the VANOS solenoids fixed. During my research, it seemed that 90% of hesitation/surging/bucking etc. threads were caused by at least one of the two solenoids. What made the most difference to my low-end power though, were the oxygen sensors, and I think they are the most often overlooked, even though they usually have a replacementment interval of around 100k. Another common problem is the eccentric shaft sensor, located on the top/front of the engine cover. The seal fails and lets oil in from behind and can cause all the symptoms you describe, so I'd pop the connector off that and check.

In your position what I'd do is start unplugging things and seeing how the car runs. What gave my most information about the problem was forcing the car to run in open-loop. My car ran great when it was forced to do so, which made me look at the components that are relied upon during closed-loop running. The car ran great with the pre-cat oxygen sensors unplugged, which lead me to replacing them. Another thing that made it better was running the car with the eccentric shaft sensor unplugged, which disables VVT and uses the throttle body for throttle input instead. There is a chance my problem is still caused by the VVT motor, so I've been thinking about throwing the replacement one back in now I've solved most of the other problems haha. I must stress though, that the thing you unplug isn't necessarily the culprit, it just narrows the problem down to a specific system.

[Our03z4]

My eccentric sensor is bone dry. I'll try changing out the o2 sensors and see if that helps. The vanos is on the list of things to do, did you do the new seals or entire replacement? I did the seals on my 03 2.5i and it worked well. Not sure if it's any different on the n52 compared to the m54?

[propaintballa]

My eccentric sensor is bone dry. I'll try changing out the o2 sensors and see if that helps. The vanos is on the list of things to do, did you do the new seals or entire replacement? I did the seals on my 03 2.5i and it worked well. Not sure if it's any different on the n52 compared to the m54?

Okay good regarding the ESS. It's different to the M54, VANOS rebuilds are not really commonplace on the N52. I have certainly not heard of anyone doing so. It's just the two solenoids at the front of the engine block that usually fail. A much less involved job. Takes 5 minutes to swap them over.

[Capa]

Glad that there is some progress on this. 95% of the problem being resolved is a forward step in my book.

On my response - the whooshing noise was unrelated. Hate to say a garage was right and all, but did turn out to be a heatsheild. Just made more of a noise as the exhaust moved around whilst the engine was under hard load from low RPM. James is very much right in the fact that there's rarely a 'single' cause of these issues though - it seems to be a cumulative effect.

Completely agree with the idea of making things run open loop. It sounds a bit lo-fi, but does move you forward as evidenced by the above.

I'm not really any further forward with mine. Just sort of accepted it as something the car occasionally does now and then and moved on with it. You can put in thousands with no end product if you're not careful.

[Our03z4]

Well after no issues for the past few weeks it came back with a vengeance, so much so I turned around and went home.

Starting to look into other cars. Went and test drove an Audi A8 the other day and I'm hooked, wife was too. If I can find a Audi S8, I'm out. Makes me sad because I really do love these cars, enough to have two currently, but this is just ridiculous!

I'm going to do one last repair blitz in hopes it will improve. Also it's sounding much louder all of a sudden, wife even commented on it. Not sure where that came from, almost sounds like the sound generator foam has been removed. Ideas?

[Capa]

I don't think anyone involved with this issue would begrudge you having a look at something else if you're able to. In fact - if it were me I'd be running off into the hills - something I still haven't ruled out.

The only thing I'd query - is it rain related? I know we have been having a lot of late...

[propaintballa]

Well after no issues for the past few weeks it came back with a vengeance, so much so I turned around and went home.

Starting to look into other cars. Went and test drove an Audi A8 the other day and I'm hooked, wife was too. If I can find a Audi S8, I'm out. Makes me sad because I really do love these cars, enough to have two currently, but this is just ridiculous!

I'm going to do one last repair blitz in hopes it will improve. Also it's sounding much louder all of a sudden, wife even commented on it. Not sure where that came from, almost sounds like the sound generator foam has been removed. Ideas?

You note that it has gotten louder... I can't remember which car you have and what your problems were, but have you checked the intake pipe? They quite often crack and would likely create the sound you're describing if it has indeed perished.

[Our03z4]

I don't think anyone involved with this issue would begrudge you having a look at something else if you're able to. In fact - if it were me I'd be running off into the hills - something I still haven't ruled out.

The only thing I'd query - is it rain related? I know we have been having a lot of late...

Nope, not rain related, we're actually in a drought in my part of the US.

Drove the car tonight...now it has developed a coolant leak from somewhere I can't locate. Nothing to do with the expansion tower either.

[Our03z4]

Well after no issues for the past few weeks it came back with a vengeance, so much so I turned around and went home.

Starting to look into other cars. Went and test drove an Audi A8 the other day and I'm hooked, wife was too. If I can find a Audi S8, I'm out. Makes me sad because I really do love these cars, enough to have two currently, but this is just ridiculous!

I'm going to do one last repair blitz in hopes it will improve. Also it's sounding much louder all of a sudden, wife even commented on it. Not sure where that came from, almost sounds like the sound generator foam has been removed. Ideas?

You note that it has gotten louder... I can't remember which car you have and what your problems were, but have you checked the intake pipe? They quite often crack and would likely create the sound you're describing if it has indeed perished.

I have an 08 Z4 Coupe with the 3.0si. I've checked before but I should again with the new issue. Thanks for the advice!

[madmutt0]

Hi have you cleaned out the two little vanos filters if you look on you tube you you can watch a video they can cause these symptoms

[enzed4]

I see there are 10 pages of this thread, so apologies if this has been raised. With the N52 engine, have you checked what spark plugs you have? IE, do you have the 4-pole plugs, and not the older single pole plugs? I've just watched a vid where the person was adamant this is the cause of a lot of rough idle problems. (ex-BMW dealer mechanic, seemed to know about the usual N52 problems - DISA valves, solenoids, rough idle, and many of the issues that get raised on this forum).
He pointed out that BMW changed to the 4 pole plugs (I think around 2008?) due to an 'update' - I got a bit confused around here so not sure what was updated (ECU?). Happy to link to the YT vid if you want.